University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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Cadmium

  • IUPAC Name: cadmium
  • Molecular Formula: Cd
  • CAS Registry Number: 7440-43-9
  • InChI: InChI=1S/Cd
  • InChI Key: BDOSMKKIYDKNTQ-UHFFFAOYSA-N

@ ChemSpider@ NIST@ PubChem

Citations 241

"Optimization Of Flame Atomic Absorption Spectrometry With Preconcentration By Flow Injection Online Sorbent Extraction Of Cadmium And Lead In Biological Materials"
Bol. Soc. Chilena Quim. 1999 Volume 44, Issue 3 Pages 321-335
BRUHN, CARLOS G., VILCHES, CAROLINA and CID, HERNAN J.

Abstract: A flow injection (FI) system with a minicolumn of bonded silica with octadecyl groups (C-18) to collect diethyldithiocarbamate complexes of Cd and Pb in reference solutions and in acid-digested hair and blood solutions was developed and evaluated by flame atomic absorption spectrometry (FAAS). The system was optimized by multivariate method, based on a factorial experimental design in two levels, selecting eight parameters that mostly affected the expected analytical signal. The detection limits (3s(BL)/slope, 60 s pre-concentration) were 0.7 and 5 µg/L for Cd and Pb, respectively and the sampling frequency was 40 samples/h. Effects of interfering ions are discussed. The methodology was validated by analysis of certified reference materials of hair and blood for Pb, and by recoveries of Cd and Pb spikes performed in hair and blood samples. Results for Pb agreed well with certified values and recoveries were satisfactory (103% in blood and 100% in hair). Also, the recovery of Cd in hair was fair (107%); however, in blood it was not quantitative (22%).
Hair Blood Spectrophotometry Preconcentration C18 Diethyldithiocarbamate Column Optimization Interferences

"The Retention Of Metal Species By Different Solid Sorbents - Mechanisms For Heavy Metal Speciation By Sequential Three Column Uptake"
Anal. Chim. Acta 2000 Volume 411, Issue 1-2 Pages 223-237
O. Abollino, M. Aceto, C. Sarzanini and E. Mentasti

Abstract: An apparatus consisting of three columns packed with different substrates, namely an anion exchange resin, a reversed phase sorbent and a chelating ion exchange resin, was developed. The retention of cadmium, copper and lead onto the substrates at different pH conditions was investigated, first by considering each column separately, then by connecting them in series. The aim of the study is to distinguish among species with different charge or chemical behaviour. Experiments were performed with the free metal ions, their anionic complexes with EDTA and 8-hydroxyquinoline-5-sulphonic acid, and their neutral complexes with 8-hydroxyquinoline. The results obtained were compared with those computed according to the theoretical species distribution of all species as a function of pH. The applicability of the technique to seawater was demonstrated.
Sea Spectrophotometry Speciation Solid phase extraction Preconcentration 8-Hydroxyquinoline Complexation C18

"Solid Phase Extraction Of Trace Metal Ions In Drinking Water Samples From Kayseri-Turkey"
J. Trace Microprobe Tech. 2000 Volume 18, Issue 3 Pages 397-403
Soylak, M.;Elci, L.

Abstract: The concentrations of Ni, Pb, Cd, Cu and Co in drinking water from wells, direct sources or storage tanks in 18 sites of Kayseri (Turkey) were determined by graphite furnace atomic absorption spectrometry, after enrichment on an Amberlite XAD-4 resin to reduce the incidence of contamination. The levels of Ni, Pb, Cd, Cu and Co in the drinking waters were in the range of 2.9 to 9.5, 2.7 to 29.9, 0.7 to 3.1, 2.0 to 21.6 and 2.1 to 6.4 µg/L, respectively. These values for the drinking water supplies of Kayseri City were below the maximum tolerable limits set by the WHO and the Water Pollution Control Regulation of the Turkish authorities. The correlation between metal ions were also calculated.
Water Spectrophotometry Preconcentration Activated carbon Preconcentration Amberlite

"Method Development For Measurement Of Elements In Hungarian Red Wines By Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES)"
Acta Aliment. 2000 Volume 29, Issue 2 Pages 105-122
Csiktusnádi-Kiss, G. A., Keszler, Á., Candeaias, M., Bronze, M. R., Boas, L. V., Spaugner, I.

Abstract: ICP-OES (inductively coupled plasma optical emission spectrometry) was used to determine the element content of red wines. Development of the method involves various procedures of sample handling as well as repeatability and reproducibility measurements. Measurements were made for the following 16 elements: Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, P, Sr and Zn. The relative standard deviation of repeatability ranged from 0.41% (potassium) to 27% (cadmium) and that of reproducibility varied between 0.73% (boron) to 52% (cobalt). Recovery of the elements was determined by standard addition with results ranging from 90.6% (phosphorus) to 116.2% (boron). After that, 15 red wine samples were measured. Significant differences were found in the Al, B, Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Na, P, Sr and Zn (P<0.001) concentration of wine samples. Correlation studies revealed parallel changes in phosphorus-potassium, phosphorus-magnesium and zinc-manganese concentrations (r=0.857, 0.875, 0.838). According to principal component analysis, measurements of zinc-, sodium-, boron-, copper- and strontium content gave almost the same results as obtained with 16 different elements. According to a two dimensional non-linear map of absolute values of principal component analysis, wines from Szekszard and Eger could be differentiated, whereas the analysis of wines from Villany, the Matra Mountains and Lake Balaton showed overlapping results.
Wine Red Spectrophotometry Volatile generation Standard method

"Simultaneous Determination Of Copper, Lead, Cadmium And Zinc Using Differential Pulse Anodic Stripping Voltammetry In A Flow System"
Anal. Chim. Acta 2000 Volume 411, Issue 1-2 Pages 201-207
J. F. van Staden and M. C. Matoetoe

Abstract: The use of differential pulse anodic stripping voltammetry (DPASV) in a how system for the simultaneous determination of Cu, Cd, Fe, Pb and Zn was evaluated for applicability with a glassy carbon electrode. Simultaneous quantitative analysis for these elements is possible at low concentrations of Fe when using pyrophosphate as a supporting electrolyte (pH 4.0). An application of the proposed method is reported for the determination of these elements in water samples. The working ranges are 50-500 µg L-1 for Cu, Cd and Pb and 100-400 µg L-1 for Zn. The Fe content was negligible in these samples. Recovery studies and metallic interferences are reported. Detection limits of 39, 9.6, 16.6 and 14.7 µg L-1 for Cu, Cd, Pb and Zn, respectively, were obtained.
Industrial Voltammetry Electrode Interferences Optimization

"Integrated Luminometer For The Determination Of Trace Metals In Seawater Using Fluorescence, Phosphorescence And Chemiluminescence Detection"
J. Autom. Methods Manag. Chem. 2002 Volume 24, Issue 2 Pages 41-47
P J Worsfold, E P Achterberg, A R Bowie, V Cannizzaro, S Charles, J M Costa, F Dubois, R Pereiro, B San Vicente, A Sanz-Medel, R V, eloise, E V, er Donckt, P Wollast, S Yunus

Abstract: The paper describes an integrated luminometer able to perform fluorescence (FL), room temperature phosphorescence (RTP) and chemiluminescence (CL) measurements on seawater samples. The technical details of the instrumentation are presented together with flow injection (FI) manifolds for the determination of cadmium and zinc (by FL), lead (RTP) and cobalt (CL). The analytical figures of merit are given for each manifold and results are presented for the determination of the four trace metals in seawater reference materials (NASS-5, SLEW-2) and Scheldt estuarine water samples.
NRCC NASS-5 NRCC SLEW-2 Fluorescence Phosphorescence Chemiluminescence Preconcentration

"An Injection Method For The Sequential Determination Of Boron And Several Metals In Waste-water Samples By Inductively-coupled Plasma Atomic Emission Spectrometry"
Anal. Chim. Acta 1979 Volume 109, Issue 1 Pages 73-83
J. A. C. Broekaert and F. Leis

Abstract: Boron and nine metals (Ba, Cd, Cu, Fe, Mn, Mo, Ni, Zn) can be determined in waste waters of medium and high salt concentration by inductively-coupled plasma atomic emission spectrometry. An injection method was applied in order to achieve analysis times of about 1 min per determination, and to allow trace analysis in solutions having salt concentrations up to 20 mg mL-1, when a Meinhard nebulizer is used with a low-power argon plasma. When 500-l aliquots are injected and the peak heights of the amplified photomultiplier signals are measured, the detection limits for the elements tested range from 0.05 to 0.4 µg mL-1. Matrix effects caused by sodium nitrate (20 mg mL-1) are less than 20%, provided that a peristaltic pump is used for feeding the nebulizer. Matrix effects can be decreased by using simultaneous background measurement. The plasma-injection method is applicable to boron and metals in the range 0.05-20 µg mL-1.
Waste Spectrophotometry

"Continuous Monitoring Of Heavy Metals In Industrial Waste Waters"
Anal. Chim. Acta 1980 Volume 114, Issue 1 Pages 303-310
H. Cnobloch, W. Kellermann, D. K&uuml;hl, H. Nischik, K. Pantel and H. Poppa

Abstract: A relatively simple instrument is described for the continuous screening of groups of heavy metal ions in sewage and waters. The method is based on coulometric principles after concentration by preelectrolysis. The following metals can be detected: Ag, Hg, Pb, Cu, Co, Fe, Cd, Zn and Ni. An automatic laboratory model of the heavy metal ion detector has been tested successfully for eight months at the inlet of a municipal sewage plant and for nine months at the outlet of a neutralization plant of a galvanic shop.
Waste Industrial Coulometry Preconcentration Silica

"Determination Of Zinc And Cadmium By Flow Injection Analysis And Chemiluminescence"
Anal. Chim. Acta 1981 Volume 127, Issue 1 Pages 199-201
J. L. Burguera and M. Burguera, Alan Townshend

Abstract: Zinc (10-100 ng mL-1 and cadmium (20-200 ng mL-1) are successively eluted from an ion-exchange column and determined by their inhibition of the cobalt-catalyzed chemiluminescence generation from luminol.
Chemiluminescence Ion exchange

"Controlled Anodic Generation Of The Catalyst In Kinetic Continuous-flow Analysis"
Anal. Chim. Acta 1982 Volume 139, Issue 1 Pages 207-217
Herbert Weisz and G&uuml;nter Fritz

Abstract: Controlled anodic dissolution of copper in a separate generator cell yields well-defined concentrations of catalyst, depending on the voltage applied. This adjustable generation of copper catalyst makes it possible to determine iron over a wide range of concentration (10-1500 g Fe3+ mL-1) via the iron(III)-thiosulphate reaction. By the copper(II)-catalyzed hydrogen peroxide-hydroquinone reaction, EDTA can be determined as an inhibitor (0.5-5 g mL-1) and cadmium(II) as a reactivator (1-10 g mL-1). As zinc(II) forms complexes with 2,2'-bipyridine, which activates copper in this reaction, it can be determined (5-50 g Zn2+ mL-1) by measuring the decrease in activation. The electrogeneration of silver ion as a catalyst is also described. The sulphanilic acid-peroxodisulphate reaction is catalyzed by silver(I), which is again activated by 2,2'-bipyridine. Zinc(II) can be determined (0.29-2.9 mg Zn2+ mL-1) by the same principle as in the copper(II)-catalyzed reaction.
Potentiometry Kinetic Catalysis Electrochemical reagent generation Review Theory

"Anodic Stripping Voltammetry Of Heavy Metals With A Flow Injection System"
Anal. Chim. Acta 1983 Volume 146, Issue 1 Pages 45-50
Joseph Wang, Howard D. Dewald and Benjamin Greene

Abstract: The design and operation of an anodic stripping voltammetric system based on the flow injection technique are described. A flow cell with a wall-jet glassy carbon disk electrode and a 500 µL sample volume are employed. The system allows trace metals at the µg L-1 level to be quantified simultaneusly at a rate of ten samples per hour. A low differential pulse background current allows a detection limit for lead of about 3 x 10^-9 M (0.3 ng) with a 3-min deposition time. Deposition is done in the presence of oxygen in the sample solution, but the carrier solution is oxygen-free.
Electrode Electrode Voltammetry

"Potential Scanning Voltammetric Detection For Flow Injection Systems"
Anal. Chim. Acta 1983 Volume 153, Issue 1 Pages 325-330
Joseph Wang and Howard D. Dewald

Abstract: The possibility was investigated of using rapid-scan differential pulse voltammetry for detection in flow injection analysis. The measurements were made with use of a flow-cell (described and illustrated) equipped with either a carbon-paste or a vitreous-carbon disc electrode, a carbon-rod auxiliary electrode and a silver - AgCl reference electrode and with potential scanning at 2 V min-1. For paracetamol, calibration graphs were rectilinear in the range 0.1 to 0.5 mM (injection volume 0.2 ml) and the limit of detection was <1 µM. At the 0.5 mM level the coefficient of variation (n = 8) was ~4%. The proposed technique permits the selective determination of several electroactive species in multi-component mixtures; as examples, the simultaneous determinations of dopamine, paracetamol and chlorpromazine and of Cu, Pb and Cd are reported.
Industrial Electrode Electrode Electrode Voltammetry Flowcell

"Determination Of Cadmium In Human Urine By Extraction With Dithizone In A Flow Injection System"
Anal. Chim. Acta 1983 Volume 153, Issue 1 Pages 207-212
J. L. Burguera and M. Burguera

Abstract: Urine (90 µL) is injected into a flowing stream (0.8 mL min-1) of 3 mM hydroxylamine - 5 mM K Na tartrate - 10 mM K4Fe(CN)6 - 10 mM tartaric acid (pH 10.5) that is subsequently mixed with 39 µM-dithizone in CHCl3 (0.8 mL min-1). The mixture is passed to a phase separator (described, with a diagram), and the absorbance of the organic phase is measured at 518 nm. Calibration graphs are rectilinear for up to 12 ng mL-1 of Cd and the limit of detection is ~0.2 ng mL-1. Recoveries of 91 to 113% were obtained and the coefficient of variation (n = 5) for 0.5 to 5 ng mL-1 was 2 or 3%. For 0.7 ng mL-1 of Cd there is no interference from 1 ng mL-1 of Co, Fe, Ni, Pb or Zn. Results agree well with those obtained by AAS
Urine Clinical analysis Spectrophotometry Sample preparation Interferences Method comparison Solvent extraction Phase separator Dithizone

"Preconcentration And Matrix Isolation Of Heavy Metals Through A Two-stage Solvent Extraction In A Flow System"
Anal. Chim. Acta 1984 Volume 158, Issue 1 Pages 147-156
Mats Bengtsson and Gillis Johansson

Abstract: Metal ions (Cd, Cu, Pb, Co and Ni) in trace amounts were isolated from sample matrices and concentrated by extraction in a flow system. The sample flow was first mixed with buffer and reagent (carbamates) and the combined aqueous flow was next segmented with trichlorotrifluoroethane (Freon 113). The metal complexes were extracted into the organic phase in a 2-m long coil which was followed by a separator with a teflon membrane. The organic phase passed on to a second segmentor where an acidic, aqueous mercury(II) solution was added. Back-extraction to the aqueous solution took place in a 1-m long coil. The Freon was removed in a second membrane separator and the aqueous phase was collected and analyzed by graphite-furnace atomic absorption spectrometer. The enrichment factors were of the order of 15-20 and the recoveries were 90-100% from the sub µg L-1 level up to 20-50 µg l-1. The recoveries decrease at concentrations above 50 µg l-1, presumably because of slow dissolution of precipitated complexes in the sample solutions. The observed recoveries for copper were generally somewhat lower, being in the range 80-90%.
Spectrophotometry Sample preparation Preconcentration Matrix removal Solvent extraction

"Online Trace Metal Enrichment And Matrix Isolation In Atomic Absorption Spectrometry By A Column Containing Immobilized 8-quinolinol In A Flow Injection System"
Anal. Chim. Acta 1984 Volume 160, Issue 1 Pages 1-10
Fottis Malamas, Mats Bengtsson and Gillis Johansson

Abstract: A flow injection system was developed for the determination of Cu(II), Co(II), Cd, Ni, Pb(II) and Zn, which incorporated their concentration and separation from the sample matrix at pH 6.5. The sample solution or water was passed, via a pneumatically operated, time-controlled injection valve, through a column packed with quinolin-8-ol azo-immobilized on 240 µL of porous glass. An aliquot (400 µL) of 1 M HCl - 0.01 M HNO3 was used to elute the metal ions; the effluent was nebulized for analysis by flame (air - acetylene) AAS Most of the components of the analytical system were constructed from PTFE. Buffer solution was pumped after the injection valve into the flowing stream. The sampling time could also be increased to improve enrichment factors, e.g., 25 min gave 500-fold enrichment from 100 mL of sample solution All the operations were controlled online. The concentration. of Cu(II) in tap-water was determined; results agreed well with those of graphite-furnace AAS
Water Ion exchange Spectrophotometry 8-Hydroxyquinoline Preconcentration Matrix removal Reactor

"Theoretical And Experimental Aspects Of The Response Of Stripping Voltammetry In Flow Injection Systems"
Anal. Chim. Acta 1984 Volume 162, Issue 1 Pages 189-196
Joseph Wang and Howard D. Dewald

Abstract: It is pointed out that, although the combination of anodic-stripping measurements with flow injection analysis has advantages in the determination of heavy metals, the expressions derived for conventional stripping voltammetry (steady-state deposition current) cannot be applied to flow injection systems. However, in this paper, expressions are derived, which show that the stripping-peak current is independent of the degree of dispersion of the sample into the carrier solution and, therefore, control of the dispersion and deposition periods can be minimized; peak current is also directly proportional to sample volume The effects of experimental variables (e.g., flow rate, length of tubing, deposition period and sample volume) on the determination of Cd support the theoretical conclusions.
Voltammetry Controlled dispersion Theory

"A Swept-potential Electrochemical Detector For Flow Streams"
Anal. Chim. Acta 1984 Volume 162, Issue 1 Pages 175-187
Patricia A. Reardon, Gerald E. O'Brien and Peter E. Sturrock

Abstract: The detector described (cf. Scanlon et al., Anal. Abstr., 1984, 46, 12C32), which is essentially a computer-controlled potentiostat, has been primarily operated in the rapid-sweep square-wave voltammetric mode for use in HPLC, flow injection analysis and ion chromatography. Programs are available for offline data processing and for visual display of any voltammogram or current vs. time plot; any real-time alphanumeric or graphics display can be copied on a dot-matrix printer. A simplified diagram of the potentiostat and a block diagram of the whole detection system linked to a HPLC system are presented. Detection limits of <1 nM (for Pb and Cd) have been attained with this potentiostat.
HPIC HPLC Potentiometry Voltammetry Apparatus Computer

"Determination Of Trace Amounts Of Heavy Metals In Waters By A Flow Injection System Including Ion-exchange Preconcentration And Flame Atomic Absorption Spectrometric Detection"
Anal. Chim. Acta 1984 Volume 164, Issue 1 Pages 41-50
Zhaolun Fang, Shukun Xu and Suchun Zhang

Abstract: The flow injection system described (see preceding abstract) has been applied to the determination of Ni, Cu, Pb and Cd. The samples (5 ml) were injected into a stream of 0.1 M ammonium acetate (pH 5.5) via a sampling loop, and the solution was passed through two columns (50 mm x 2.5 to 3 mm) filled with a chelating ion-exchange resin containing a salicylic acid functional group. Elution was effected with 2 M HNO3, and Ni, Cu, Pb and Cd were determined in the eluate by AAS, with absorption measurements at 232.0, 324.8, 283.8 and 228.8 nm, respectively, and use of an air - acetylene flame. At a sampling rate of 40 h-1, the sensitivity was enhanced 20 to 28-fold in comparison with that attained by direct aspiration of the sample solution into the flame. With the exception of Cd, recoveries of the metals from sewage, tap-water and seawater were generally satisfactory; coefficient of variation were generally 4.1% (n = 11).
Waste Sea Water Waste Ion exchange Spectrophotometry Chelation Resin Preconcentration

"An Efficient Flow Injection System With Online Ion-exchange Preconcentration For The Determination Of Trace Amounts Of Heavy Metals By Atomic Absorption Spectrometry"
Anal. Chim. Acta 1984 Volume 164, Issue 1 Pages 23-39
Zhaolun Fang, J. Rika and E. H. Hansen

Abstract: The flow injection system described (with diagrams) incorporated a multi-functional eight-channel rotary valve that permitted simultaneous loading of duplicate samples on to two identical columns (35 mm x 2.8 mm). Sequential elution was then effected by intermittent pumping with use of two pumps that were controlled by a dual-channel timer, and the eluate was analyzed by flame AAS Columns of Chelex-100 and of chelating ion-exchange resins based on salicylic acid and quinolin-8-ol were used for the pre-concentration of Cu, Zn, Pb and Cd from seawater. The degree of pre-concentration ranged from 50 to 105-fold at a sampling rate of 60 h-1, and the limits of detection were typically 0.07 to 0.09, 0.03 to 0.04, 0.5 to 0.8 and 0.05 to 0.07 µg L-1 for Cu, Zn, Pb and Cd, respectively.
Sea Ion exchange Spectrophotometry Chelation Chelex Resin Preconcentration 8-Hydroxyquinoline

"Differential Pulse Voltammetry With Fast Pulse Repetition Times In A Flow Injection System With A Copper-amalgam Electrode"
Anal. Chim. Acta 1984 Volume 166, Issue 1 Pages 119-127
Peter W. Alexander and Umaporn Akapongkul

Abstract: The flow system, equipment and electrodes used have been described previously (Ibid., 1983, 148, 103). Ammoniacal buffer solution (1M), containing 8 mM NaHSO3, was pumped (at 2.8 mL min-1) to a flow-cell containing an amalgamated copper wire as working electrode, a platinum wire as auxiliary electrode and a SCE The sample solution, 0.1 mM Cd(NO3)2 and 0.1 mM Zn(NO3)2 in the buffer were injected through a liquid chromatography septum injector with a hypodermic syringe. With 100-ms repetition times, signal-to-background ratio improved for both voltage scanning and amperometric operation, giving scan rates of up to 100 mV s-1 and detection limits of 0.07 to 0.15 ng of Cd and Zn after de-aeration of sample solution Peak widths were obtained for Cd and Zn at the baseline in the range 12 to 30 s, depending on flow rate, at working potentials of -0.77 and -1.27 V, respectively. The sensitivity of the system was improved by a factor of 10 compared to DC operation, but the selectivity was limited by overlapping peaks or co-deposited metals.
Water Electrode Voltammetry Peak width

"Determination Of Cadmium By Suction-flow Liquid - Liquid Extraction Combined With Inductively Coupled Plasma Atomic-emission Spectrometry"
Anal. Chim. Acta 1985 Volume 174, Issue 1 Pages 183-189
Takahiro Kumamaru, Yoko Nitta, Fumio Nakata and Hiroshi Matsuo, Masahiko Ikeda

Abstract: A flow-manifold system is proposed that permits specific online suction-flow liquid extraction of Cd as its diethyldithiocarbamate from a discrete aqueous sample into CCl4 (I). The organic extract is fed into the nebulizer of the ICP spectrometer by a peristaltic pump, to achieve a 250-fold increase in sensitivity compared with direct aspiration of the aqueous solution The sampling frequency is 20 h-1 and the consumption of I and of 5% (w/v) Na diethyldithiocarbamate solution is 0.6 mL min-1. The calibration graph is rectilinear up to 300 ppb of Cd, the detection limit is 0.4 ppb, the coefficient of variation (n = 10) at the 50-ppb level is 1.5%, and only Mn(II), Co(II) and Ni interfere significantly. Such interference can be decreased or eliminated by the addition of citrate to the buffer solution Interference by large amounts of alkali and alkaline-earth metals and most anions can be avoided by extraction. The proposed method was applied to the determination of Cd in NBS SRM 1571 orchard leaves, NIES (Japan) CRM No. 1 pepperbush and CRM No. 6 mussel to give results in good agreement with the certified values.
NIST 1571 NIES 1 NIES 6 Plant Spectrophotometry Sample preparation Interferences Nebulizer Reference material Solvent extraction

"Response Characteristics Of A Potentiometric Detector With A Copper Metal Electrode For Flow Injection And Chromatographic Determinations Of Metal Ions"
Anal. Chim. Acta 1985 Volume 177, Issue 1 Pages 183-195
Peter W. Alexander and Paul R. Haddad, Marek Trojanowicz

Abstract: The nitrate salts of Ca, Ba, Al, Pb(II), Cd, Co(II), Cu(II), Ni(II), Mn(II) and Zn were injected into the stream of a flow injection system; a flow cell with a copper-wire electrode was used for detection. The carrier solution consisted of a buffered solution of some ligands, e.g., citric acid, EDTA, ethylenediamine, triethylenetetramine, L-glutamic acid and iminodiacetic acid. Potential changes due to introduction of the metal ions into the ligand flow stream were measured by a millivoltmeter interfaced to a recorder. The electrode response depended on the nature of the ligand in the carrier solution and on the stability of the metal complexes formed. The method was successfully applied for the chromatographic separation of some cations on a Wescan 269-004 cation-exchange resin column (25 cm x 4.6 mm). Rectilinear responses were obtained for analyte metal concentration. of 0.1 to 1.0 mM.
Electrode Potentiometry Complexation EDTA

"Combination Of Flow Injection Techniques With Atomic Spectrometry In Agricultural And Environmental Analysis"
Anal. Chim. Acta 1986 Volume 179, Issue 1 Pages 325-340
Zhaolun Fang, Shukun Xu, Xiu Wang and Suchun Zhang

Abstract: A review is presented, with 37 references, in which the applications of the coupled techniques are discussed with emphasis on agricultural and environmental analyzes.
Agricultural Environmental Ion exchange Spectrophotometry Spectrophotometry Spectrophotometry Spectrophotometry Spectrophotometry Review Preconcentration Standard additions calibration

"Flow Injection Potentiometric Stripping Analysis-a New Concept For Fast Trace Determinations"
Anal. Chim. Acta 1986 Volume 179, Issue 1 Pages 389-398
Wolfgang Frenzel and Peter Br&auml;tter

Abstract: The system described by Schulze and Frenzel (Mikrochim. Acta, 1984, I, 191) was used with four different flow-through cells. The carrier solution contained various amounts of Hg and the vitreous carbon was pre-coated with Hg. Up to four elements could be determined simultaneously at ppb to % levels. Rectilinear response was obtained for Pb and Cd in the range 5 to 100 µg l-1. The method was sucessfully applied to the determination of Zn, Pb and Cu in tap-water at levels down to 20 µg L-1 with 0.5 mL samples and to the direct determination of Pb and Cd in acid digests of biological samples.
Biological material Water Electrode Potentiometric stripping analysis Sample preparation Tecator

"Constant-potential Pulse Polarographic Detection In Flow Injection Analysis Without Deaeration Of Solvent Or Sample"
Anal. Chim. Acta 1986 Volume 179, Issue 1 Pages 381-388
Glen G. Neuburger and Dennis C. Johnson

Abstract: The use of constant-potential-pulse polarography enabled the detection of Pb(II) and Cd in solution (pH 7) to be carried out at a dropping-mercury electrode without de-aeration of sample or solvent. The supporting electrolyte was 0.1 M KNO3 - 0.01 M HNO3. The method was used in conventional polarographic cells or, for small samples, in flow injection systems; the determination of Cu(II) in electroplating solution is described.
Copper Polarography Electrode

"Sensitivity Enhancement For Inductively-coupled Plasma Atomic Emission Spectrometry Of Cadmium By Suction-flow Online Ion-exchange Preconcentration"
Anal. Chim. Acta 1986 Volume 181, Issue 1 Pages 271-275
Takahiro Kumamaru and Hiroshi Matsuo, Yasuaki Okamoto, Masahiko Ikeda

Abstract: A column of iminodiacetate chelating resin is used to pre-concentrate cadmium by a factor of 25-fold for a 5 mL sample. The sampling rate was 25 h-1, and the detection limit 0.05 ng Cd2+ mL-1. The RSD for 0.1 µg Cd2+ mL-1 was 2.2% (n = 10). This technique was applied to the determination of cadmium in certified biological reference materials and waste-water samples.
Ion exchange Spectrophotometry Preconcentration Sensitivity

"Simultaneous Determination Of Multiple Components In Flow Injection Systems By Square-wave Amperometry"
Anal. Chim. Acta 1987 Volume 192, Issue 2 Pages 327-331
T. P. Tougas and C. Y. Yuan

Abstract: Ions of Cu, Cd, Zn and Pb were detected in a flow injection system with 0.1 M acetate buffer (pH 4.5) as carrier stream. The flowcell detector included a potentiostat, a static-mercury-drop electrode and a silver - AgCl reference electrode. A computer was used to superimpose a square wave on the applied staircase potential. Currents were sampled every 250 µs from each square wave to evaluate the current - time responses. The response of each ion was independent of the concentration. of the other ions. Rectilinear calibrations were obtained over the range 0.05 to 10 mg mL-1 and detection limits were 11, 13, 8 and 8 µg mL-1 for Cu, Cd, Zn and Pb, respectively.
Amperometry Electrode Computer

"Determination Of Bismuth, Cadmium And Lead In Soil By Atomic Absorption Spectrometry With Loop Sample Introduction"
Anal. Chim. Acta 1987 Volume 196, Issue 1 Pages 277-282
S. G&uuml;cer and M. Demir

Abstract: Bismuth, cadmium and lead in soil extracts with aqua regia, 2 M nitric acid, 2.5% acetic acid or ammonium acetate solution from top-soils at different locations in Turkey, were determined by atomic absorption spectrometry with loop sample introduction. Detection limits were 0.8, 0.025 and 0.5 µL-1 for bismuth, cadmium and lead, respectively, after concentration with ammonium pyrrolidinedithiocarbamate. Use of a silica tube for atom trapping improved the detection limits.
Environmental Sample preparation Spectrophotometry

"Determination Of Zinc And Cadmium In Small Amounts Of Biological Tissues By Microwave-assisted Digestion And Flow Injection Atomic Absorption Spectrometry"
Anal. Chim. Acta 1988 Volume 214, Issue 1-2 Pages 421-427
M. Burguera and J. L. Burguera, O. M. Alarc&oacute;n

Abstract: A system comprising a microwave oven, a peristaltic pump, a closed flow system and an AAS instrument is described and illustrated. Samples of liver or kidney were prepared in a final volume of 10 mL of 10 M HNO3, and then digested in the oven at ~200 W for 8 min. The digest was aspirated into a collector tube, pumped to a flowing sample collector, and finally injected into the carrier stream (H2O). Zinc and Cd were determined by flame AAS in an air - acetylene flame at 213.9 and 228.8 nm, respectively. Recoveries of 20 to 60 µg of Zn and of 5 to 10 µg of Cd were 97 to 103 and 96 to 98%, respectively. The coefficient of variation (n = 5) were 2 to 5% and 3 to 6% for Zn and Cd, respectively, and results for two reference materials agreed with expected values.
Kidney Liver Sample preparation Spectrophotometry Reference material

"Trace Metal Enrichment By Automated Online Column Preconcentration For Flow Injection Atomic Absorption Spectrometry"
Anal. Chim. Acta 1989 Volume 221, Issue 1 Pages 65-76
Shizuko Hirata, Kazuto Honda, Takahiro Kumamaru

Abstract: Trace metals were pre-concentrated on a micro-column (7 mm x 4 mm) of Muromac A-1 (50 to 100 mesh) at a flow rate of 5 mL min-1. Ions were eluted with 2 M HNO3 (4.85 mL min-1), before analysis by flame AAS. Optimum pH was established for metal ion uptake from sample solution The coefficient of variation for 20 mL samples containing 5 to 100 µg L-1 of Cd, Cr, Cu, Fe, Mn, Pb or Zn were 0.7 to 1.7% (n = 3 or 4). Values for Cd and Cr in standard reference materials of plants, mussel tissue and pond sediment were within the specified range.
Mussel Pond Spectrophotometry Column Preconcentration Muromac Reference material Optimization pH

"Design Of A Continuous-flow Two-step Extraction Sample Work-up System For Graphite Furnace Atomic Absorption Spectrometry"
Anal. Chim. Acta 1990 Volume 232, Issue 1 Pages 301-315
Kenneth B&auml;ckstr&ouml;m and Lars-G&ouml;ran Danielsson

Abstract: A manifold for continuous-flow analysis is described and illustrated. Samples (1.1 ml) were injected and mixed with the reagent stream (0.3% of ammonium pyrrolidinecarbodithioate, 0.3% of diethylammonium diethyldithiocarbamate and 14 mM NH3 in 0.25 M NaHCO3) and the heavy-metal complexes were extracted with Freon 114. In the second extraction step, the metal ions were back-extracted into aqueous 0.1% Hg(NO3)2. Specially designed falling drop segmentors were used. After the back-extraction step, the system was connected online with a graphite-furnace AAS instrument. The graphite sample tubes were fitted with a small internal barrier to prevent excessive solution spreading during deposition. With this system, the concentration. factors were 50 to 100-fold, and the sample throughput was 30 h-1, with a max. carry-over of 1.2%. Extraction yields were in the range 80 to 107% for Cd, Co, Cu, Fe, Ni and Pb, coefficient of variation were 1.5 to 2.7% and detection limits were 10 ng l-1. Zinc could not be determined because of high blanks from the pump tubing.
Spectrophotometry Sample preparation Extraction

"Online Preconcentration And Determination Of Trace Elements By Flow Injection Inductively Coupled Plasma Atomic-emission Spectrometry"
Anal. Chim. Acta 1991 Volume 248, Issue 1 Pages 241-249
S. Caroli, A. Alimonti and F. Petrucci, Zs. Horv&aacute;th

Abstract: Columns (5 cm x 2 mm) of iminodiacetic acid - ethylcellulose chelating resin (I; 100 to 200 mesh) were used to pre-concentrate trace elements in a computer-assisted online flow injection analysis - ICP-AES technique. Elements of clinical and environmental importance (Cd, Co, Cu and Pb) in water, seawater and urine were determined. A 4-way rotary valve assembly was used to fill the column with solution (mixed with 2 M acetate buffer, pH 5.5), elute the analytes with 2 M HNO3, push the eluent plug with a countercurrent flow of water carrier to the excitation source and wash the column. Sample throughput was 10 to 12 h-1. Compared with pre-concentration. on carboxymethylated polyethyleneimine - polymethylenephenylene isocyanate and Chelex 100 resins, the online mode using I gave a 2- to 4-fold improvement in detection limits and a reduced column volume of about a fifth. Detection power is improved at least one order of magnitude for Cd and Pb in seawater.
Urine Water Sea Spectrophotometry Column Preconcentration Chelex

"Online Preconcentration System For Inductively Coupled Plasma Atomic Emission Spectrometry With Quinolin-8-ol And Amberlite XAD-2 Resin"
Anal. Chim. Acta 1992 Volume 258, Issue 2 Pages 237-244
Valerio Porta, Corrado Sarzanini, Edoado Mentasti* and Ornella Abollino

Abstract: An online pre-concentration. system implemented with inductively coupled plasma atomic emission spectrometry (ICP-AES) was studied for water anal. For the retention of metal ions, 8-hydroxyquinoline and Amberlite XAD-2 resin were used. This system improved the detection limits of Cd, Cu, Fe, Mn, Ni, and Zn by a factor of 100, compared with ICP-AES alone. The method was applied to the determination of the above metals in Antarctic seawater. The concentration. was 16 ng Mn/L and 0.4 µg Ni/L, with a precision of 10%.
Sea Spectrophotometry Amberlite Resin Preconcentration 8-Hydroxyquinoline

"Determination Of Trace Elements In Seawater By Flow Injection Anodic Stripping Voltammetry Preceded By Immobilized Quinolin-8-ol Silica Gel Preconcentration"
Anal. Chim. Acta 1992 Volume 258, Issue 2 Pages 245-252
Bor-Jian Daih and Hsuan-Jung Huang*

Abstract: The sample (5 or 10 ml), adjusted to pH 1.6 to 7 for Cu, 3 to 4 for Bi or In, or 6 to 7 for Pb, Cd or Zn, was passed through a column (5 cm x 3 mm) of the cited gel, and the metals were eluted with 1.0 M HCl - 0.1 M HNO3 at 0.22 or 0.33 mL min-1. After being mixed with 0.5 M Na acetate the solution was analyzed in a flow-through cell at a vitreous-carbon working electrode. The coefficient of variation (n = 10) for 1.0 µg L-1 of the test ions were from 2.5 to 6.9%. The results on CASS-2 reference seawater gave reasonably good agreement with the certified values for Cd and Cu, but the Pb concentration was larger and the Zn concentration smaller than the certified value. Procedures based on the application of immobilized quinolin-8-ol silica gel and stripping voltammetry were developed for the determination of Cu, Pb, Cd, Bi, In and Zn in seawater. As two concentration steps are involved, better sensitivity and lower detection limits could be achieved with the application of smaller sample volumes. The feasibility and reliability of the procedures were confirmed by the anal. of a near-shore seawater sample and CASS-2 reference seawater.
Sea NRCC CASS-2 Voltammetry Immobilized reagent 8-Hydroxyquinoline Reference material Silica gel Preconcentration

"In-flow Speciation Of Copper, Zinc, Lead And Cadmium In Fresh Waters By Differential-pulse Anodic Stripping Voltammetry. 1. Optimization Of Filtration And Enrichment Steps"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 323-334
W. Martinotti* and G. Queirazza, F. Realini, G. Ciceri

Abstract: An automatic system for the in-situ determination of dissolved Cu, Zn, Pb, and Cd in fresh waters, composed of a filtration unit, a separation and enrichment unit, and an electrochemical unit for differential-pulse anodic stripping voltammetry, was investigated. The filtration and enrichment units were designed to establish the most effective experimental conditions for the measurement of the metal concentrations at environmental levels. The system was built for installation in a buoy equipped with a facility for radiotransmission of the data obtained.
River Voltammetry Remote instrument Automation Optimization Filtration Speciation

"Time-based And Volume-based Sampling For Flow Injection Online Sorbent-extraction Graphite-furnace Atomic Absorption Spectrometry"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 477-487
Bernhard Welz*, Xuefeng Yin and Michael Sperling

Abstract: Separation of the analyte from the sample matrix, and its pre-concentration, were achieved by use of a Perkin-Elmer model FIAS-200 flow injection accessory having its sample loop replaced by a conical micro-column (Eppendorf pipette tip) packed with 15 µL of RP-C18 solid-phase sorbent. The flow injection manifold was connected to the sample-introduction capillary of a Perkin-Elmer model Zeeman/3030 AAS instrument equipped with an HGA-600 graphite tube furnace and an AS-60 furnace autosampler. Details and diagrams are given of the sequence of operations for pre-concentration, involving volume-based sub-sampling; the system was more sensitive than one involving time-based sub-sampling. The system was applied in the determination of Cd, Cu, Pb and Ni. The acidified sample was mixed with a pre-purified 0.05% solution of Na diethyldithiocarbamate (I) in 0.06 M NH3 - 0.03 M acetic acid buffer (pH 9), and the metal - I complex was adsorbed on the micro-column. The column was then washed in the reverse direction with 0.02% (v/v) HNO3 before elution of the complex with ethanol and transfer of only 40 µL of the eluate to the graphite tube; furnace operating parameters are specified. With 60-s pre-concentration. of the analyte, the detection limits for Cd, Cu, Ni and Pb were 0.6, 8.5, 21 and 4 ng l-1, respectively. The method was used to determine the cited metals in standard reference seawater (open-ocean and coastal), estuarine water and river water; results agreed well with reference values. Flow injection online pre-concentration. systems for graphite furnace atomic absorption spectrometry are complicated by the low eluate volume of typically less than 50 µL which can be accommodated in a graphite tube or on a graphite platform. Even when a column with an extra small capacity of 15 µL was used, it was found impossible to elute the sorbed analyte completely with an eluate volume that was compatible with the capacity of the graphite furnace. Two approaches for introducing only the most concentrated fraction of the eluate into the graphite tube while discarding the rest were investigated and compared: controlling the time interval for collection and introduction of the eluate fraction into the furnace tube (time-based sampling), and collection of the eluate fraction of interest in thin tubing of fixed volume, followed by introduction of this fraction into the tube using a low flow of air (volume-based sampling). Cadmium, copper, lead and nickel were the analyte elements investigated. A 15-30% greater enhancement factor was obtained for volume-based sampling because dispersion was interrupted during sample injection by air segmentation. The short- and long-term reproducibility were also better for volume-based sampling because variations in the pump tubing had no influence on the eluate volume introduced. These combined effects resulted in an improvement in detection limits of the four elements by factors of 1.3-2.0. Sample throughput (23 h-1), sample consumption (3 mL min-1) and reagent consumption were the same for both approaches. There were no significant differences in the accuracy and precision of the two techniques in the anal. of seawater, estuarine water and river water standard reference materials.
Estuarine Sea River Spectrophotometry Sample preparation Matrix removal Preconcentration Timed injection Reference material FIAS-200 Reagent consumption Solid phase extraction

"Use Of A PH Gradient In Flow Injection Analysis In Differentiating Zinc And Cadmium In A Binary Mixture"
Anal. Chim. Acta 1993 Volume 281, Issue 2 Pages 229-242
N. Porter, B. T. Hart*, R. Morrison and I. C. Hamilton

Abstract: A pH gradient was formed by injecting a 25 mM sodium tetraborate/0.1 M KOH solution of pH 12.2 into a carrier stream of 0.04 M potassium dihydrogen orthophosphate of pH 4.8 which was then merged with 0.1 mM 8-hydroxyquinoline-5-sulfonic acid followed by a sample stream containing Zn and Cd. The fluorescence of Zn and Cd was measured as a function of time. The pH of the stream was measured using a flow-through pH cell placed directly after the fluorescence detector. With a pH gradient of 4-12 and back to 4 over 90 s, a doublet fluorescence response was obtained for both Zn and Cd. The distance between the two peaks of each doublet differed sufficiently to allow the resolution of binary mixtures of the two metals. The method of steepest descent was the mathematical procedure used to resolve the individual components of the binary mixture. A detection limit of 0.05 µM was obtained for both Zn and Cd. The detection limit is similar to that obtained by AAS, but FIA is less expensive, has the potential to be made portable and can measure a number of variables simultaneously.
Fluorescence pH gradient 8-hydroxyquinoline-5-sulfonic acid

"Online Trace Metal Ion Preconcentration In Ion Chromatography Using Carboxymethyl And Hydroxamate Dextran-coated Silicas"
Anal. Chim. Acta 1993 Volume 283, Issue 1 Pages 344-349
N. Ryan and J. D. Glennon*, D. Muller

Abstract: With use of a system incorporating a six-way valve, the metal ions were concentrated from aqueous solution adjusted with 0.5 M LiOH to pH 7 on a column (5 cm x 4 mm i.d.) of chelating adsorbent prepared by treating carboxymethyl dextran-coated silica with hydroxylamine [Srijaranai and Glennon, Analyst (London), 1990, 115, 627]. The metal ions were eluted on to a Dionex Analytical CS5 column for separation with 50 mM oxalic acid/95 mM LiOH of pH 4.8 as mobile phase (1 ml/min). A 0.3 mM 4-(2-pyridylazo)resorcinol solution (0.6 ml/min) was used for post-column derivatization and detection was at 520 nm. The method was used for the pre-concentration and determination of Pb, Cu, Cd, Co, Mn, Zn and Ni, and was applied to the determination of metals in domestic and laboratory tap-water and in river water. Limits of detection were 5-10 ng/ml of Cu, Mn, Co, Zn and Ni but >100 ng/ml for Pb and Cd.
Water River HPIC Spectrophotometry Preconcentration Silica Post-column derivatization Immobilized reagent

"Determination Of Cadmium, Copper And Lead In Environmental Samples. An Evaluation Of Flow Injection Online Sorbent Extraction For Flame Atomic Absorption Spectrometry"
Anal. Chim. Acta 1994 Volume 285, Issue 1 Pages 33-43
Renli Ma, Willy Van Mol and Freddy Adams*

Abstract: Lake, estuarine or river sediment, calcareous loam soil or coal fly ash were digested in a PTFE bomb with concentrated HF and HNO3 by heating until fuming. After cooling HClO4 was added, the bomb was sealed and heated for 8 h at 150°C. Silicates were removed by repeated addition of HF and HNO3 and evaporation to dryness and the residue was dissolved in HNO3, HCl and water. The solution was injected into a FIA system and mixed with 0.2% ammonium diethyldithiophosphate in 0.1 M citric acid adjusted to pH 1 with HNO3. Following pH dependent complexion with 0.1% diethylammonium-NN-diethyldithiocarbamate in 0.1 M acetic acid (described), 50 mM citric acid was added to mask Fe(III) and Mn(II). The complexes were sorbed onto C18 bonded silica gel (40-63 µm) in a conical extraction column, eluted with methanol and analyzed by AAS; elution rates and AAS nebulizer uptake rates are discussed. Calibration graphs of peak height were linear up to 50 µg/l of Cd, 300 µg/l of Cu and 1 mg/l of Pb with detection limits of 0.8, 1.4 and 10 µg/l, respectively, with a 20 s sample loading at 8.7 ml/min.
Estuarine Lake River Loam Coal Fly ash Sample preparation Spectrophotometry Sample preparation Silica gel C18 Precipitation Solid phase extraction

"Selective Flow Injection Sorbent-extraction For Determination Of Cadmium, Copper And Lead In Biological And Environmental Samples By Graphite-furnace Atomic Absorption Spectrometry"
Anal. Chim. Acta 1994 Volume 293, Issue 3 Pages 251-260
Renli Ma, Willy Van Mol and Freddy Adams*

Abstract: Biological material was heated with HNO3 to fuming, cooled, HClO4 was added, heated at 150°C for 8 h in a sealed bomb and the contents diluted for analysis. Geological material was digested with HF and HNO3 to fuming, digested as above, the bomb contents were evaporated to dryness and the residue dissolved in HNO3. Seawater of pH 1.5 and estuarine water of pH 2 were filtered. Samples were transferred to the FIA system, the stream (8.7 ml/min) was merged with an ammonium diethyldithiophosphate/0.1 M citric acid stream (2.2 ml/min; 0.01% for Cu, 0.1% for Pb and 0.2% or 0.5% for Cd in digests and seawater, respectively) and passed through the ODS sorbent extraction column (40-63 µm) for 20-80 s. After rinsing, elution was effected with ethanol at 5.7 ml/min for 2 s. The eluate was analyzed by GFAAS at 228.8, 324.8 and 283.3 nm and charring/atomization temperature of 400/1500, 1100/2500 and 1100/2300°C for Cd, Cu and Pb, respectively. Calibration graphs were linear up to 0.1, 5 and 4 µg/l with detection limits of 0.003, 0.05 and 0.04 µg/l of Cd, Cu and Pb, respectively. The recoveries for 25-50 ng/l of Cd, 0.5-1 µg/l of Cu and 50 ng/l of Pb from sea and estuarine waters were >87.6%.
Biological Geological Sea Spectrophotometry Sample preparation Solid phase extraction

"Rapid Determinations Of Complexing Stability Constants By Gradient Flow Injection Titration"
Anal. Chim. Acta 1995 Volume 302, Issue 1 Pages 97-102
A. C. Lopes da Concei&ccedil;&atilde;o, M. L. S. Sim&otilde;es Gon&ccedil;alves* and M. M. Correia dos Santos

Abstract: The equilibrium constants for the cadmium-glycine system were determined by gradient flow injection (FI) titration using potentiometric detection with a glass electrode. In gradient FI titrations, the injection valve is switched once and the transition between carrier and sample solution is monitored following dispersion in a gradient chamber. In this way, a simulation of a titration is carried out in a few minutes. For the model system studied, titration graphs were prepared in the pH range 7.7-8.8 using different pairs of solutions to cover different concentration ranges of the metal and ligand. The formation constants for the complexes ML and ML2 of Cd2+ with glycine were then calculated by non-linear least squares regression analysis. The results were in agreement with those obtained by batch titration measurements and also with literature values. The use of rapid gradient flow-injection titration for the determination of equilibrium constants in solution, previously used in pK measurements of monobasic and multibasic weak acids is extended to the more demanding case of metal complexation. Formation constants for the complexes ML and ML2 of Cd2+ with glycine have been determined by that technique using potentiometric detection with a glass electrode. Under optimum conditions formation constants in good agreement with batch and literature values are obtained in several minutes.
Potentiometry Equilibrium constants Gradient technique Titrations Stability constants Complexation

"Determination Of Trace Metals In Natural Waters By Flame Atomic Absorption Spectrometry Following On-line Ion-exchange Preconcentration"
Anal. Chim. Acta 1995 Volume 303, Issue 2-3 Pages 341-345
M. C. Yebra-Biurrun, A. Bermejo-Barrera, M. P. Bermejo-Barrera* and M. C. Barciela-Alonso

Abstract: An on-line column pre-concentration technique for flow-injection flame atomic absorption spectrometry has been developed for the determination of trace metals in natural waters. A minicolumn (20 mm x 2 mm i.d.) filled with a poly(aminophosphonic acid) chelating resin (PAPhA, 20-30 mesh) was used for the pre-concentration procedure. For 2 mL samples, detection limits of 0.5, 5.0, 1.5, 1.6, 3.5, 0.6, 3.2, 3.1 and 0.4 g 1-1 for Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn, respectively, were achieved. The precision (coefficient of variation) obtained was in the range between 1.1 (Cd and Cu) and 3.3% (Co). Accuracy was also investigated and results agreed with the certified values of the reference material. The sampling rate was 48 h-1. The method was applied to the determination of trace metals in natural waters samples from Galicia (Spain).
Environmental Ion exchange Spectrophotometry Preconcentration Column Resin Reference material

"In-flow Speciation Of Copper, Zinc, Lead And Cadmium In Fresh Waters By Square-wave Anodic-stripping Voltammetry. 2. Optimization Of Measurement Step"
Anal. Chim. Acta 1995 Volume 305, Issue 1-3 Pages 183-191
W. Martinotti, G. Queirazza, A. Guarinoni and G. Mori*

Abstract: Square-wave anodic-stripping voltammetry measurements were performed in a wall-jet type flow cell with a glassy carbon working electrode (5 mm diameter), a Ag/AgCl/3 M KCl reference electrode and a Pt counter electrode. The five other units of the system (potentiostat, thermometer, current measurement block, ultrasound generator and pump/valve driver) were controlled by a micro-processor. A measurement cycle consisted of three rinse steps, a Hg-film renewal step and two identical measurement steps. Each measurement step had six separate phases, (i) heavy metal deposition at -1100 mV, (ii) first rest period with pump off, (iii) stripping current measurement with square wave potential ramp from -1100 to +100 mV at 2000 mV/s with square wave period of 5 ms, step height of 10 mV and square wave amplitude of 25 mV, (iv) cleaning of the Hg film by oxidizing the heavy metals at a constant potential and with the pump on, (v) rest period with pump off and (vi) background current measurement as in (iii). The flow rate through the detector cell was 0.9 ml/min and measurements were made with a supporting electrolyte of 0.2 M HNO3. A fresh Hg film was deposited on the working electrode before each measurement cycle by electrolysing a mercury nitrate solution. Calibration graphs were linear for up to 100 µg/l of Zn, 5 µg/l of Cd and 15 µg/l of Pb and Cd in water. The complete measurement cycle took ~e;30 min.
Environmental Voltammetry Electrode Electrode Speciation Computer Optimization

"Determination Of Cadmium In Foodstuffs And Plant Materials By Flow Injection Spectrophotometry Including Ion Exchange"
Anal. Chim. Acta 1995 Volume 306, Issue 2-3 Pages 343-349
Jos&eacute;A. Gomes Neto, H. Bergamin Filho, Raquel P. Sartini and Elias Ayres G. Zagatto*

Abstract: Dried powdered food or plant material (1 g) was digested with 10 mL of HNO3 for 30 min at 50°C; 2 mL of 30% H2O2 was added and the mixture evaporated to near dryness at 110°C. The residue was dissolved in 10 mL of 0.1 M HNO3 and diluted to 25 mL with water for FIA. The sample stream (3.8 ml/min) merged with an acidic NaCl stream (1.2 ml/min) then the flow passed through a strongly basic AG1 X-8 BioRad column (1 cm x 5 mm i.d.) and the Cd chlorocomplexes were retained. The flow-through the column was reversed and the analyte was eluted with 2 M NaNO3/0.1 M HNO3 (2.9 ml/min). The flow was merged with 75 µg Cd in 0.25 M ammonium acetate solution (1.2 ml/min) and then a second reagent stream which had been formed by merging 0.5 mM Malachite green and 2 M KI in 0.5% ascorbic acid (both at 0.5 ml/min); detection was at 690 nm. The detection limit was 0.11 µg/l Cd; RSD for sample digests containing 19.7 and 5.12 µg/l Cd were 2.26% and 2.72%, respectively (n = 12). The method was validated by analyzing standard reference materials (rice flour, pig kidney, dried copepoda) containing 0.75-2.71 µg/g Cd (results given). A second anion-exchange column was added to the FIA system to enable the analysis of samples which had been mineralized with HNO3/perchloric acid.
Kidney Opepoda Food Rice Flour Plant Ion exchange Spectrophotometry Biorad Reference material

"Determination Of Metal Ion Mixtures Using PH Gradient Flow Injection Analysis With Fluorescence Detection"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 313-328
N. Porter*, B. T. Hart, R. Morrison and I. C. Hamilton

Abstract: A pH gradient flow injection system with fluorimetric detection was described for the analysis of ternary and quaternary mixtures of Zn, Cd, Pb, Mg and Al. The pH gradient was formed by injecting a basic buffer solution into an acidic buffer stream. Four different buffer systems were used. For each system the pH variable buffer stream was merged with 0.1 mM 8-hydroxyquinoline-5-sulfonic acid and sample streams. The flow then passed through a knotted PTFE mixing coil (30 cm x 0.5 mm id.) and a column (18 cm x 2.5 mm i.d.) containing 0.25 mm glass beads to the detection cell (90 µL) where the metal chelates were monitored at 520 nm (excitation at 369 nm). All measurements were carried out in triplicate with each run taking 60 s. The fluorescence-time scans were analyzed by a partial least squares algorithm. The dynamic range of the method was 0.1-10 µM for Zn, Cd, Al and Mg. The method was used to analyze tap water. The results were comparable to those obtained by AAS.
Water Fluorescence pH gradient Method comparison Glass beads Chelation 8-hydroxyquinoline-5-sulfonic acid Knotted reactor Partial least squares

"Online Coated Columns For The Spectrophotometric Determination Of Metals By Continuous-flow Analysis"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 378-385
Yuri A. Zolotov, Irina M. Maksimova, Elena I. Morosanova* and Andrei A. Velikorodny

Abstract: Online coated microcolumns and capillary tubes were evaluated for the separation and pre-concentration of metal ions by continuous-flow analysis. Xylenol orange, 1-(2'-pyridylazo)-2-naphthol and (p-sulfophenylazo)-2'-sulfo-4'-nitrodiazoaminobenzene disodium salt (Cadion) were immobilized on reversed-phase silica (C16, C8, phenyl, C1) packed into microcolumns (2.5 cm x 2 mm i.d.) or on capillary tubes (10 m x 2 mm i.d.) with hydrophobic inner surfaces (C6, C-phenol, C1). The optimum conditions for the maximum retention of reagent were determined. The adsorption and acid desorption of metal ions from coated microcolumns and capillaries were studied and procedures for the determination of Cd, Co, Cu and Fe(III) in the range 0.08-30 µM were suggested using spectrophotometric detection. Preconcentration factors of up to 9 and 19 were achieved with coated microcolumns and capillaries, respectively.
Spectrophotometry Column Immobilized reagent Optimization Preconcentration Silica

"Determination Of Cadmium In Fertilizers By Flow Injection Spectrophotometry"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 439-445
Jos&eacute;Anchieta Gomes Neto, H. Bergamin, Elias Ayres G. Zagatto* and Francisco J. Krug

Abstract: The flow injection procedure for the determination of Cd in fertilizers was based on the formation of the blue ternary complex between Cd, iodide and Malachite Green (MG). The fertilizer solution was injected into a 0.05 M HNO3 carrier stream (3.2 ml/min) using a 150 cm sampling loop. The stream was successively merged with reagents R1, R2 and a previously mixed stream of reagents R3 and R4. R1 was 0.01 M picolinic acid in 0.6 M sodium acetate/0.1 M acetic acid buffer at 0.4 ml/min. R2 was 200 µg/l Cd in 0.05 M HNO3 at 0.8 ml/min. R3 was 2 M KI in 5 mg/ml ascorbic acid solution at 0.4 ml/min and R4 was 0.5 M MG at 0.4 ml/min. The formed ternary complex was propelled to the detector where the absorbance was measured at 690 nm. The calibration graph for Cd was linear for up to 200 µg/l and the detection limit was 2 µg/l. The RSD (n = 10) for the determination of 93 and 35.3 µg/l of Cd were 1.3 and 4%, respectively. Interfering ions (Hg2+, Ag+, Cu2+ and Pb2+) were removed by inserting a Chelex-100 ion exchange column (5 cm x 3 mm i.d.; 50-100 mesh) into the sample stream. The sampling frequency was 60 samples/h. The results were confirmed by tungsten coil-AAS.
Commercial product Lobster Vegetable Spectrophotometry Chelex Complexation Interferences Method comparison

"Anodic-stripping Voltammetry Of Trace Metals By Batch-injection Analysis"
Anal. Chim. Acta 1996 Volume 322, Issue 3 Pages 151-157
Christopher M. A. Brett*, Ana Maria Oliveira Brett and Laura Tugulea

Abstract: Trace metals in sample volumes of 100 µL were determined by square wave anodic-stripping voltammetry using a batch-injection procedure. The measurements were carried out at a Hg film deposited on a vitreous C electrode with a Pt gauze counter electrode and a SCE as the reference electrode. Injections were performed using a programmable motorized electronic micropipette for the accurate additions of 10^-100 µL. Optimum experimental parameters were determined for the in situ formation of the Hg film, the pre-concentration time and the injection rate and injection volume of analyte. These values were used to determine Pb, Cd, Zn and Cu. Detection limits of 2-3 nM were achieved for Pb and Cd in a background electrolyte of 0.1 M KNO3/2 mM HNO3 with an injection volume of 50 µL at 24.5 µL/s, a deposition time of 30 s at -1.3 V and a potential scan in the positive direction with square wave parameters of 25 mV amplitude, 2 mV scan increment and 100 Hz frequency. The linear range extended to 1 µM. The results obtained by the proposed batch-injection procedure were compared to those obtained by FIA and a continuous-flow system with a wall-jet electrode.
Voltammetry Preconcentration Batch injection analysis

"Hair Analysis. 1. Differential Pulse Anodic Stripping Voltammetric Determination Of Lead, Cadmium, Zinc, Copper In Human Hair Samples Of Persons In Permanent Contact With A Polluted Workplace Environment"
Anal. Chim. Acta 1996 Volume 335, Issue 3 Pages 201-207
Wieslaw Wasiak*, Wanda Ciszewska and Aleksander Ciszewski

Abstract: Prior to determination of Pb, Cd, Zn and Cu by differential pulse anodic stripping voltammetry microwave digestion has been evaluated for the decomposition of human hair samples using a HNO3---H2O2 mixture. The efficiency of the decomposition, and the accuracy and precision of the proposed procedure was studied using a human hair standard. Hair samples were collected from the vertex of the scalps of donors who were employed in factories manufacturing lead-acid batteries, nickel-cadmium batteries and gas (petroleum) vending station workers. The results show that, in all cases, permanent contact with the polluted environment makes it possible to absorb very large amounts of lead or cadmium, simultaneously depressing zinc absorption. Results of a study on the content of the above elements in human hair of persons who had had no work place contact with these elements are also presented.
Hair Voltammetry

"On The Suppression Of Zinc-copper Interactions In Square Wave Anodic-stripping Voltammetry In Flowing Solution By Addition Of Gallium Ions"
Anal. Chim. Acta 1997 Volume 339, Issue 1-2 Pages 167-172
Christopher M. A. Brett*, M. Beatriz Quinaz Garcia and Jos&eacute; L. F. C. Lima

Abstract: The use of Ga3+ to suppress the formation of Cu-Zn intermetallic compounds during square wave anodic-stripping voltammetry in continuous-flow systems was investigated. The study was carried out using a three-electrode assembly consisting of a Hg thin film electrode on a vitreous C substrate (3 mm diameter), a Ag/AgCl (3 M KCl) reference electrode and a Pt counter electrode. The recommended procedure for determining Zn in the presence of Cu used a supporting electrolyte containing 40 µM-Ga3+ in 0.1 M acetate buffer of pH 4.75 or in 0.1 M sodium perchlorate of pH 3. A deposition potential of -1.4 V was applied for 120 s and the stripping voltammogram was recorded in the square-wave mode after the flow was stopped for 20 s. Under these conditions, a linear calibration graph was obtained for 5-20 nM-Zn and the detection limit was ~20 pM. To analyze mixtures of Cu, Zn, Pb and Cd, two two-stage procedures were recommended, namely, (i) the measurement of Cd, Pb and Cu after deposition at -0.9 V followed by the addition of Ga3+ solution and the depoon of Zn at -1.4 V or (ii) the measurement of Cu after deposition at -0.5 V followed by the addition of Ga3+ solution and the deposition of Zn, Cd and Pb at -1.4 V.
Voltammetry Electrode Interferences

"Simultaneous Flow Injection Analysis Of Cadmium And Lead With Differential Pulse Voltammetric Detection"
Anal. Chim. Acta 1997 Volume 340, Issue 1-3 Pages 149-158
J. Alp&iacute;zara, A. Claderab, V. Cerd&agrave;b,*, E. Lastresc, L. Garc&iacute;ac and M. Catas&uacute;sa

Abstract: A flow injection differential pulse voltammetric detection method was used to analyze Cd/Pb mixtures. The flow-through detection cell was equipped with a static Hg-drop working electrode (0.71 mm2), a saturated calomel reference electrode and a Pt wire auxiliary electrode. The voltage sequence was: -300 mV for 400 ms, -350 mV for 174 ms, -550 mV for 174 ms, -300 mV for 400 ms, -600 mV for 174 ms and -800 mV for 174 ms. The sample injection volume was 200 µL and the carrier stream was 0.1 M KCl at a flow rate of 1.2 ml/min. The data was processed using a neural network as the Cd and Pb signals were not completely resolved. Calibration graphs were linear from 8-16 µg Cd and 4-16 µg Pb in 200 µl; recoveries were 89-104% and 78-185% Cd and Pb, respectively.
Voltammetry Electrode Simultaneous analysis Neural network

"Complex Formation Of 2-(5-nitro-2-pyridylazo)-5-(N-propyl-N-sulfo-propy Lamino)phenol With Lead, Cadmium And Manganese For Their Sensitive Spectrophotometric Detection In Flow Injection And Ion Chromatography Systems"
Anal. Chim. Acta 1997 Volume 345, Issue 1-3 Pages 139-146
Takeshi Yamane* and Yuzuru Yamaguchi

Abstract: An ion-chromatographic method with post-column derivatization and spectrophotometric detection was developed for the simultaneous determination of Pb, Cd and Mn. Analysis was carried out on a strongly acidic cation-exchange column (7 cm x 4 mm i.d.). Elution (1 ml/min) was with 0.15 M malic acid of pH 5. The injection volume was 588 µL. The column effluent was merged with a reagent stream containing 60 µM-2-(5-nitro-2-pyridylazo)-5-(N-propyl-N-su lfo-propylamino)phenol/0.2 M 2-(cyclohexylamino)ethanesulfonic acid/0.16 M NaOH of pH 9.4 at a flow rate of 1 ml/min. Detection was at 574 nm. Calibration graphs were linear up to 150 ng/ml Cd and Mn, and 300 ng/ml Pb; detection limits were 1.9, 1.5 and 4.8 ng/ml, respectively. RSD were 2.1%, 2.5% and 3.2% for 50 ng/ml Cd, Mn and Pb, respectively. The method was verified by analyzing rice flour CRM following microwave assisted digestion and river water samples spiked with Cd, Mn and Pb.
Rice River NIES 10 HPIC Spectrophotometry Sample preparation Post-column derivatization Reference material Interferences

"Flow Injection Online Coprecipitation-preconcentration System Using Copper(II) Diethyldithiocarbamate As Carrier For Flame Atomic Absorption Spectrometric Determination Of Cadmium, Lead And Nickel In Environmental-samples"
Anal. Chim. Acta 1997 Volume 353, Issue 2-3 Pages 181-188
Hengwu Chen*, Jincao Jin and Yufeng Wang

Abstract: A novel flow injection (FI) online coprecipitation-pre-concentration system with diethyldithiocarbamate (DDTC) Copper(LI) being used as a carrier for the flame atomic absorption spectrometric determination of trace cadmium, lead and nickel was developed. Sample solutions, spiked with 120 µg mL-1 Cu2+ and acidified to 0.5 M with hydrochloric acid, were merged online with a 2.1% DDTC solution in a 'T' connector upstream of a knotted reactor. The analytes were coprecipitated with DDTC-Cu2+ and collected on the inner wall of the knotted reactor. The collected species were eluted with isobutyl methyl ketone, and the effluent was transported directly into the nebulizer. Enhancement factors of 26, 45 and 22 were obtained for cadmium, lead and nickel, respectively with a loading period of 30 s. The detection limits (3s) for cadmium, lead and nickel were 0.23, 3.2 and 1.4 µg L-1 respectively, and the relative standard deviations (n=10) were 1.4% for 20 g L-1 cadmium, 2.0% for 200 µg L-1 lead and 2.2% for 80 µg L-1 nickel. At least 50 mg L-1 of such metal ions as Fe3+, Al3+, Mn2+, Zn2+ and Co2+, and 30 mg L-1 of Cu2+ could be tolerated. The method has been successfully applied to the determination of trace cadmium, lead and nickel in various water samples and a standard reference soil. 18 References
Water Environmental Spectrophotometry Preconcentration Coprecipitation Interferences Reference material Knotted reactor MIBK Diethyldithiocarbamate

"Speciation Of Copper, Lead, Cadmium, And Mercury In Waters Of The Oporto Coast In Portugal, Using Preconcentration In A Chelamine Resin Column"
Anal. Chim. Acta 1997 Volume 353, Issue 2-3 Pages 189-198
M. Teresa S. D. Vasconcelos* and M. Fernanda C. Leal

Abstract: Sea water was collected monthly between January and March 1996 from the shore of the Oporto coast at three different representative sampling points and speciation of Cu, Pb, Cd and Hg were carried out. For the purpose, total particulate (retained on a 0.45 µm pore-size filter), particulate sorbed to inorganic matter, total dissolved, and dissolved and operationally labile metal was discriminated. The filters were digested by microwaves. The filtered water was pre-concentrated on a microcolumn of Chelamine, eluted with 5 mL of 2 mol L-1 HNO3 and analyzed by flame atomic absorption spectrometry (FAAS) or mercury cold vapor (CVAAS) for Hg. Spike recovery percentages did not differ significantly (P>0.05) from 100% for any metal studied. The organic matter (OM) destruction was performed by UV photolysis. For quality control of the results, determination of Cu, Pb and Cd total dissolved concentration by differential pulse anodic stripping voltammetry was also performed; for Hg only the pre-concentration in the column was changed to partial evaporation of the sea water, followed by CVAAS. No statistically significant difference was observed between the results provided by the comparative methods. Online pre-concentration with Chelamine showed to be expeditious and effective for extraction of the heavy metals in coastal waters. The distribution of each metal in the different fractions, including ascertainment of significant correlation between pairs of metal fractions and the respective partition coefficients, is discussed.
Environmental Preconcentration Speciation Resin

"Online Preconcentration Of Lead And Cadmium For Flame Atomic Absorption Spectrometry Using A Flow-through Electrochemical Microcell"
Anal. Chim. Acta 1997 Volume 357, Issue 1-2 Pages 133-140
Ewa Bulska*, Maciej Wa

Abstract: A method was developed for the trace determination of lead and cadmium by flame atomic absorption spectrometry (FAAS) with electrochemical pre-concentration. Both metals were deposited on the glassy-carbon electrode in a flow-through microcell of volume 3 µL. At a consumption of a 3 µL sample volume, the procedure resulted in an enhancement factor of more than 20 and yielded a detection limit of 1 µg L-1 for Pb and 0.08 µg L-1 for Cd. The relative standard deviation (n=12) was 2.1% at the 100 µg L-1 level for Pb and 3.2% at the 8 µg L-1 level for Cd. Results obtained for the standard reference material, water SRM 1643 c, were in good agreement with the certified values.
Spectrophotometry Preconcentration Electrochemical stripping

"Potentiometric Flow Injection Determination Of Cadmium In Waste Waters Including Inline Ion-exchange Separation/concentration"
Anal. Chim. Acta 1998 Volume 366, Issue 1-3 Pages 155-161
Cristina M. C. M. Coutoa, Jos&eacute; L. F. C. Limaa, M. Concei&ccedil;&atilde;o B. S. M. Montenegroa, Boaventura F. Reisb and Elias A. G. Zagattob,*

Abstract: A flow injection system including an ion exchange resin mini-column was proposed for potentiometric determination of Cd in wastewater. Cd was preferential and quantitatively retained as chloro-complex by a strongly basic anion exchange resin (AG 1-X8, 200-400 mesh, chloride form) mini-column (2.0 cm height, 1.85 mm inside diameter), whereas other sample metallic cations and inert components were wasted. Retained complexes were further eluted towards detection. The flow-through detector was a Cd homogeneous crystalline double membrane tubular electrode of increased sensitivity; summation of the potentials related to each membrane was performed using an external electronic device. This system was used to determine Cd in residual wastewater; Cd concentrations were 0.056-56.2 mg/L. Precise results (relative standard deviation ~7%) in agreement with those obtained by flame atomic absorption spectrometry were obtained at a rate of 15-20 determinations/h.
Waste Potentiometry Ion exchange Electrode Electrode Complexation Resin Preconcentration Method comparison

"Online Separation And Preconcentration Of Cadmium, Lead And Nickel In A Fullerene (C60) Minicolumn Coupled To Flow Injection Tungsten Coil Atomic Absorption Spectrometry"
Anal. Chim. Acta 1998 Volume 368, Issue 3 Pages 255-263
Marcia M. Silvaa, Marco A. Z. Arrudab, Francisco J. Kruga,*, Pedro V. Oliveirac, Zilvanir F. Queiroza, Mercedes Gallegod and Miguel Valc&aacute;rceld

Abstract: A flow system was coupled to a W coil electrothermal atomizer (150 W) for online separation and pre-concentration of Cd, lead and Ni based on the formation of DDC complexes and sorption into a minicolumn packed with fullerene C60. Three way solenoid valves used for sample and reagents management as well as the W coil power supply were controlled by a computer running a program written in Visual Basic, which was employed in synchronism with the original software of the atomic absorption spectrometer. The fullerene column (5 mm length, 2 mm internal diameter) was inserted into the tip of the autosampler arm, and elution was performed by sampling 35 µL of MeOH from the autosampler cup. With 3.0 mL of sample (loading time of 60 s) enrichment factors ranging from 100 to 150 were achieved. The detection limits for Cd, lead and Ni were 2.2, 23 and 75 ng L-1, respectively. No interference effects were observed on Cd, lead and Ni pre-concentration in the presence of up to 106 fold concentrations of Na, K, Ca or Mg. Application of t-test to the results obtained by the proposed method and the certified values of Cd, lead and Ni in five water reference materials did not reveal significant differences at the 5% probability level.
Environmental Blood Spectrophotometry Preconcentration Fullerene Column Interferences Reference material Complexation

"Use Of 4-(2-pyridylazo)resorcinol Or 2-(2-pyridylazo)-5-dimethylaminophenol As Chelating Agent For Determination Of Cadmium In Seawater By Atomic Absorption Spectrometry With Online Flow Injection Sorbent Extraction"
Anal. Chim. Acta 1998 Volume 376, Issue 3 Pages 305-311
Pi-Guey Su and Shang-Da Huang*

Abstract: A home-made automatic online flow injection sorbent extraction system for graphite furnace atomic absorption spectrometry (GFAAS) was used to determine Cd in seawater using octadecyl functional group (C18) bonded silica gel as sorbent, 4-(2-pyridylazo)resorcinol (PAR) or 2-(2-pyridylazo)-5-dimethylaminophenol (PADMAP) as chelating agent and methanol as eluent. The range of pH for the determination of Cd in seawater was 4.7-7.4 and 7.1-9.0 for using PAR and PADMAP as chelating agents, respectively. For the long-term stability studies, (PAR-Cd or PADMAP-Cd) are stable within the pH range 4.7-7.4 (for PAR) or 7.1-9.0 (for PADMAP) for 1 h at least. Sample volume of only 500-1000 µL was required to determine Cd in seawater. The simple calibration curve method was used and the detection limits of the determination of Cd in seawater were 4.0 and 1.7 ng L-1 for PAR and PADMAP as chelating agents, respectively. The sample throughput is 9-12 h-1. The accuracy and precision of the method were confirmed by the anal. of three kinds of certifie reference saline water.
Sea Spectrophotometry Preconcentration Reference material C18 Chelation pH

"Determination Of Cadmium In Seawater Using Automated Online Preconcentration And Direct Injection Graphite Furnace Atomic Absorption Spectrometry"
Anal. Chim. Acta 1998 Volume 377, Issue 2-3 Pages 255-262
D. Colbert, K. S. Johnson and K. H. Coalea

Abstract: An online pre-concentration method for the determination of cadmium in seawater was developed for graphite furnace atomic absorption spectrometry (GFAAS) using deuterium lamp background correction. The technique was adapted from a previously reported technique and was fully automated. Automated pre-concentration of cadmium reduced the concentrations of matrix elements in samples to levels that did not interfere with the determination of cadmium at ultratrace levels. The soluble ligand, 1-pyrrolidinecarbodithioic acid (APDC), was mixed with the sample in a continuous-flow system to form a nonpolar metal complex which was absorbed onto a C18 column. The metal complex was then eluted from the column directly into the graphite furnace. The addition of an inline nitric acid rinse step between sample load cycles allowed for the determination of cadmium with one elute cycle. Other modifications included lab. purifn. of the ammonium acetate rinse solution, a nonbuffered APDC ligand solution, and a computer-activated load cycle to reduce sample consumption. The average column recovery was 73% with a sample loading flow rate of 2.2 mL/min and 55 s pre-concentration time. Sample throughput was ~15 samples/h with 2 mL of sample pre-concentrated and analyzed every 4 min. The small sample volume required made this method useful where sample volumes are limited. The 3s limit of detection for replicate blanks was 42 pM Cd (n = 5) for a 2 mL sample. The effectiveness of the method was demonstrated for the determination of Cd in certified open ocean reference materials NASS-3 and NASS-4. Analysis of Cd in equatorial Pacific seawater demonstrated that the system produces oceanographically consistent results.
Sea NRCC NASS-3 NRCC NASS-4 Spectrophotometry Preconcentration Reference material C18 APDC

"Flow Injection Analysis Of Traces Of Lead And Cadmium By Solvent Extraction By Dithizone"
Talanta 1980 Volume 27, Issue 2 Pages 169-175
O. Klinghoffer, J. Rika and E. H. Hansen

Abstract: An automated solvent extraction method for determination Pb and Cd down to the 50 ng/ml level has been developed. Optimum conditions for selective and sensitive determination were designed and verified by using the flow injection scanning method. Application to pollution control is discussed.
Environmental Spectrophotometry Sample preparation Solvent extraction Optimization PPB Dithizone

"Automated Square-wave Anodic-stripping Voltammetry With A Flow-through Cell And Matrix Exchange"
Talanta 1982 Volume 29, Issue 3 Pages 207-211
E. B. Buchanan, Jr. and D. D. Soleta

Abstract: An extremely sensitive and versatile instrument is described that performs square-wave anodic-stripping voltammetry. The instrument incorporates a flow-through cell and is capable of changing the solution matrix between the deposition and stripping steps. The working electrode is a static mercury drop electrode constructed in the authors' laboratories. The entire system is controlled by a microcomputer that allows the usual variation of the square-wave parameters, as well as setting of the initial and final scan potentials, the deposition time, the scan-rate, the instrument sensitivity and the drop size. To show the performance of the instrument, calibration graphs for Cd in the ranges 0.2-40 and 0.1-1 ng/ml are described and the reproducibility of the drop is discussed. Analysis of a NaCl sample for Cd is given as an example of application of the method.
Electrode Voltammetry Automation

"Continuous-dilution Calibration Technique For Flame Atomic Absorption Spectrophotometry"
Talanta 1984 Volume 31, Issue 1 Pages 9-14
J. F. Tyson and J. M. H. Appleton

Abstract: The rapid, automatic calibration procedure presented is based on a flow injection technique (mixing-chamber gradient method); it requires no curve-fitting approximations, and extends over the whole working concentration. range of the analyte, irrespective of the shape of the conventionally obtained calibration graph. The theory of the method and a schematic diagram of the apparatus are given. Results for the determination of Mg, Cr and Ni are presented and discussed. With well designed apparatus, deviations of <1% should be attainable; deviations of <4% were obtained.
Spectrophotometry Calibration Dilution Gradient technique Mixing chamber

"Background Current Subtraction In Voltammetric Detection For Flow Injection Analysis"
Talanta 1984 Volume 31, Issue 5 Pages 387-390
Joseph Wang* and Howard D. Dewald

Abstract: Compensation for background currents due to evolution of H, reduction of O, solvent oxidation or surface processes was made by recording the voltammogram while the sample and carrier solution flowed through the cell and taking the difference as the net response for the sample. The electrochemical detector was that described previously (Anal. Chim. Acta, 1983, 153, 325). Various 3-mm diameter disc working electrodes were used, including mercury-coated vitreous carbon (for measurements in the cathodic region), bare vitreous carbon and carbon paste. A silver - AgCl reference electrode and a carbon-rod auxiliary electrode were used. All measurements were made with a Sargent-Welch model 4001 polarograph. At a flow rate of 0.3 mL min-1, ~15 samples per h could be analyzed. The coefficient of variation for 25 µM-Pb was 0.4% (n = 7); other test analytes included Bi, phenol, chlorpromazine and noradrenaline.
Environmental Electrode Electrode Electrode Voltammetry

"Determination Of Cadmium, Lead And Copper In Milk And Milk Powder By Means Of Flow Potentiometric Stripping Analysis"
Talanta 1986 Volume 33, Issue 12 Pages 991-995
L. Alamestrand, D. Jagner and L. Renman

Abstract: A flow potentiometric stripping analysis procedure for the determination of cadmium, lead and copper in milk and milk powder samples is described. The instrumental arrangement consists of a glassy-carbon thin-layer cell through which six different solutions may be drawn by means of a peristaltic pump and magnetically operated valves. The glassy-carbon electrode is pre-coated with a film of mercury which can be employed for several analytical runs. The sample, diluted five-fold with Suprapur hydrochloric acid, is electrolysed for 0.5-4 min prior to stripping in Suprapur hydrochloric acid. Pump-rate, electrolysis time and potential, opening and closing of inlet valves and digital evaluation of stripping times are controlled automatically by the computer. The analytical results agree satisfactorily with the certified values for three milk powder reference samples. The detection limit for cadmium, lead and copper in milk samples after 4, 1 and 0.5 min of pre-electrolysis is 0.8, 4 and 8 µg/l., respectively. An analytical procedure for the determination of lead in samples containing high concentrations of tin is described.
Milk Powder Potentiometric stripping analysis

"Manual And Flow Injection Analysis Methods For The Determination Of Cadmium With Malachite Green And Iodide"
Talanta 1988 Volume 35, Issue 11 Pages 885-889
I. Lopez Garcia, P. Navarro and M. Hernandez Cordoba

Abstract: Sample solution (20 ml) containing 50 µg of Cd was mixed with 1 mL of KI - ascorbic acid solution, 1 mL of 2 M acetate buffer solution (pH 4) and 2 mL of poly(vinyl alcohol) solution, and then 1 mL of malachite greeen(I) solution was added. After 15 min, the absorbance was measured at 685 nm vs. a reagent blank. Beer's law was obeyed for 0.04 to 2 µg mL-1 of Cd. The coefficient of variation (n = 10) for 1 µg mL-1 of Cd was 1.7%. The method was adapted for flow injection analysis by using a two-channel manifold with reaction coils of 1 m and 25 cm (both i.d. 0.5 mm) and flow rates of 1.4 mL min-1. The optimum concentration. for carrier solution were 0.08 M KI and 0.25 mM I both in 0.1 M acetate buffer (pH 4). The calibration graph was rectilinear for 0.1 to 3 µg mL-1 of Cd, and the coefficient of variation for 1.5 µg mL-1 of Cd was 1.8%. Tolerance levels for foreign ions are tabulated. The flow injection method was more selective than the batch method. The method was applied to determine Cd in solution from Zn manufacturing, and results agreed with those obtained by AAS. Recovery of Cd was 99 to 102%.
Process liquor Spectrophotometry Interferences Merging zones Method comparison

"Determination Of Cadmium, Lead And Copper In Water Samples By Flame Atomic Absorption Spectrometry With Preconcentration By Flow Injection Online Sorbent Extraction"
Talanta 1991 Volume 38, Issue 6 Pages 613-619
Zhaolun Fang, Tiezheng Guo and Bernard Welz*,

Abstract: Sample was mixed with aqueous 0.05% diethylammonium diethyldithiocarbamate and the heavy metal complexes formed were concentrated on a 5-mm micro-column of Bakerbond C18 bonded silica (40 to 63 µm). The complexes were eluted with ethanol or methanol (2.5 mL min-1) and determined by flame AAS at 283.3, 228.8 and 324.7 nm, for Pb, Cd and Cu, respectively. The flow injection system is described in detail (diagrams given). The operating conditions were optimized and the methods was applied in the analysis of seawater, drinking water and a reference material. Results for the latter agreed with certified values. Recoveries of Cd and Pb from seawater and potable water were 94 to 102%. Detection limits were 0.3, 3 and 0.2 µg L-1 of Cd, Pb and Cu, respectively; coefficient of variation (n = 11) were 1.5%. Sampling rate was 120 h-1.
Sea Water Spectrophotometry Sample preparation Column Extraction Preconcentration Reference material C18 Optimization

"Flow Injection Spectrophotometric Determination Of Cadmium With Quinolylazo Compound After Online Separation Using A Silica Gel Column"
Talanta 1994 Volume 41, Issue 5 Pages 799-803
Tomosuke Ishizuki, Koji Matsumoto, Akio Yuchi, Tadao Ozawa, Hiromichi Yamada and Hiroko Wada*

Abstract: The flow injection manifold (schematic given) consisted of a double-plunger pump, a peristaltic pump, a ceramic injector with a 100 µL loop, a spectrophotometric detector, a mixing coil (20 cm x 0.5 mm i.d.) and two PTFE columns (25 cm x 2 mm i.d.) filled with silica gel. Both the reagent solution and carrier were pumped at 0.75 ml/min. The reagent stream was aqueous 50% ethanol containing 20 µM-2-[2-(4-methylquinolyl)azo]-5-diethyl-aminophenol (QADP) and 0.1 M NH3/NH4Cl at pH 10. Two carrier streams were examined: 0.04 M H3PO4/KOH of pH 7/0.42 M KCl and 5 mM citric acid/0.5 M N-2-hydroxyethylpiperazine-N'-3-propanesulfonic acid/KOH of pH 8/0.45 M KCl. Absorbance was monitored at 569 nm. Calibration graphs were linear for both phosphate (1-6 µM-Cd) and citrate (0.4-1.6 µM-Cd). The detection limit was 19 µg/l of Cd at a signal-to-noise ratio of 3 with an RSD (n = 3) of 0.7%. The method was used to determine Cd in artificial samples containing Cd, Zn, Pb and Fe.
Spectrophotometry Silica gel

"Determination Of Cadmium In Biological Materials By Flame Atomic Absorption Spectrometry With Flow Injection Online Sorption Preconcentration"
Talanta 1994 Volume 41, Issue 12 Pages 2165-2172
Zhaolun Fang*, Shukun Xu, Liping Dong and Wenqing Li,

Abstract: A new on-line pre-concentration flame atomic absorption spectrometry (FAAS) system for trace element determination was developed based on sorption of soluble metal complexes on the walls of a PTFE knotted reactor using flow injection techniques. The system was applied to the determination of cadmium in biological materials. Cadmium complexed with sodium diethyldithiocarbamate was sorbed on the inner walls of the reactor and eluted on-line by isobutyl methyl ketone. The retention efficiency was 81% at a sampling loading rate of 5.2 ml/min. The enhancement factor was 66 and the concentration efficiency was 61/min with a 50 sec pre-concentration period, consuming 4.2 mL sample. A detection limit of 0.1 µg/l. Cd (3s) was obtained with a sampling frequency of 55/hr. The precisions were 1.2% RSD for 20 µg/l. Cd (N = 11). Thiourea and ascorbic acid/phenanthroline were used to overcome interferences from copper and iron, respectively. The analytical results obtained for powdered rice and human hair standard reference materials were in good agreement with the certified values.
Hair Rice Flour Spectrophotometry Preconcentration

"Flow Injection Online Column Preconcentration For Low Powered Microwave Plasma Torch Atomic-emission Spectrometry"
Talanta 1996 Volume 43, Issue 4 Pages 535-544
Ye Dongmei, Zhang Hanqi and Jin Qinhan*

Abstract: Sample solutions in 0.05 M NH4Cl/NH3 buffer of pH 9 were pumped at 1.7 ml/min through a column (3.5 cm x 3 mm i.d.) packed two-thirds full with a thiol resin (type 190) similar to Duolite ES-465. After 1 min, the adsorbed cations were eluted in the reverse direction with 1 M HCl (1.3 ml/min) into a desolvating system of a heated glass tube, a water-cooled condenser and a wash vessel of concentrated H2SO4. The concentration solution was then transported into a pneumatic concentric nebulizer with Ar as carrier gas. The microwave plasma torch conditions were optimized for the detection of Cd(II), Cu(II), Mn(II) and Zn(II). Enrichment factors of 4-5 were achieved. Calibration graphs were linear for 0.01-20 µg/ml (0.05-20 µg/ml for Mn), with detection limits of 1.8-3.6 ng/ml. For 0.3 µg/ml of Cd(II), Cu(II) and Zn(II) and 1 µg/ml of Mn(II) the RSD were 0.7-1.2% (n = 3). Large amounts of alkali metals, which can interfere with the plasma emission, were eliminated in the pre-concentration step.
Spectrophotometry Interferences Preconcentration

"Flow Injection Determination Of Lead And Cadmium Traces With Graphite Furnace Atomic Absorption Spectrometry"
Talanta 1997 Volume 44, Issue 5 Pages 867-875
M. Colognesi, O. Abollino, M. Aceto, C. Sarzanini and E. Mentasti*

Abstract: Natural or potable water sample, 10 mM Tiron solution (1,2-dihydroxy-3,5-benzenedisulfonic acid) and ammonium borate buffer of pH 9 were loaded at 1 ml/min into a pre-concentration manifold (diagram given) and pumped through a column (1.5 cm x 3.9 mm i.d.) of macroporous anion-exchange resin (AGMP-1; BioRad, 100-200 mesh, chloride form). The bound Pb and Cd were eluted with 0.1 M HCl and the eluate was collected in to a sampling cup for GFAAS using a matrix modifier of NH4H2PO4/magnesium nitrate. The program details are tabulated. Pb and Cd were determined at 283.3 nm and 228.8 nm, respectively. Recoveries were 92.7±0.4% for Pd and 28±1% for Cd. Using a batch method, Cd recoveries were higher. Detection limits were 9 and 7 ng/l for Pb and Cd, respectively, for a pre-concentration ratio of 5O. No calibration data are given. Interferences and the effect of Tiron purity were investigated.
Environmental Water Spectrophotometry Column Preconcentration Complexation Interferences Tiron Column Resin Biorad

"Immobilization Of 8-hydroxyquinoline Onto Silicone Tubing For The Determination Of Trace Elements In Seawater Using Flow Injection ICP-MS"
Talanta 1998 Volume 47, Issue 2 Pages 439-445
S. N. Willie*, H. Tekgul and R. E. Sturgeon

Abstract: A rapid and simple online method is described for the pre-concentration of Mn, Co, Ni, Cu, Zn, Cd and Pb from seawater using 8-hydroxyquinoline immobilized onto silicone tubing (Sil-8-HQ) via the Mannich reaction. Recoveries 35-95% and limits of detection in the ppt range were obtained using a 2 m long Sil-8-HQ tube with a sample flow rate of 1.0 mL/min. A tube could be subjected to sample loading and elution cycles over 200 times. The capacity was 1.5 and 1.3 µg/cm2 for Cu and Mn, respectively. Cu, Cd, Co, Pb, Mn, Zn and Ni were determined in coastal and open ocean seawater using flow injection inductively coupled plasma mass spectrometry (FI-ICP-MS). Good agreement with certified values for the certified reference materials NASS-4 and CASS-3 was demonstrated when quantitation was undertaken by the method of additions
Sea NRCC NASS-4 NRCC NASS-3 Mass spectrometry Tube wall immobilization Silicone tubing 8-Hydroxyquinoline Preconcentration Reference material Standard additions calibration

"Combination Of Flow Injection Analysis With Flame Atomic Absorption Spectrophotometry. Determination Of Trace Amounts Of Heavy Metals In Polluted Seawater"
Analyst 1983 Volume 108, Issue 1289 Pages 905-917
Svend Olsen, Luiz C. R. Pessenda, Jaromir Rika and Elo H. Hansen

Abstract: A Varian model AA-1275 spectrophotometer with FIAstar injection unit was used, with 0.5 mM H2SO4 as carrier solution (4.9 mL min-1), to analyze from 180 to 250 samples per h; Cd, Cu, Pb and Zn were determined at 228.8, 324.7, 217.0 and 213.9 nm, respectively, with corresponding detection limits of 9, 5, 32 and 10 ppb. Calibration graphs were rectilinear for, e.g., 2 to 20 ppm of Pb. A two-line FIAstar injection system, with directional valve and peristaltic pumps, was developed to allow analysis of seawater after pre-concentration of the metals on Chelex-100 (NH4+ form). Results showed good agreement with those obtained by potentiometric stripping analysis. Automation of the system is described.
Sea Ion exchange Spectrophotometry Resin Preconcentration Chelex Tecator

"Sample Work-up For Graphite Furnace Atomic Absorption Spectrometry Using Continuous-flow Extraction"
Analyst 1984 Volume 109, Issue 3 Pages 323-325
Kenneth B&auml;ckstr&ouml;m, Lars-G&ouml;ran Danielsson and Lage Nord

Abstract: A two-stage method is described for extracting and concentrating metals. The sample (containing traces of Cu, Co, Fe, Ni, Pb, Cd and Zn in 0.7 M NaCl made 0.014 M in HNO3; pH 5; flowing at 6 mL min-1) and reagent (0.1% of ammonium pyrrolidine-1-carbodithioate and 0.1% of diethylammonium diethyldithiocarbamate, in 0.3 M acetate buffer of pH 5.5; flow rate 1 mL min-1) are mixed and extracted with 1,1,2-trichlorotrifluoroethane, at 1.5 mL min-1, in a coil, with phase separation by use of a membrane (cf. Nord and Karlberg, Anal. Abstr., 1981, 40, 4J6). The organic layer is back-extracted with Hg(II) in 0.2 M HNO3 at a flow rate of 0.19 mL min-1 in a second coil, and the aqueous phase is separated in a glass T-piece of low dead volume and collected. Five 5 to 10 mL samples are collected in an 8-h period and are analyzed directly by flame AAS for each element. Recoveries are 80 to 95%, but lower for Co. A 25 to 30-fold concentration of the metals is obtained, except for Co (15-fold). The aqueous concentrate finally obtained at a flow rate of 200 µL min-1 is suitable for injection for graphite-furnace AAS
Spectrophotometry Sample preparation Extraction Membrane

"Simultaneous Determinations In Flow Injection Analysis. A Review"
Analyst 1984 Volume 109, Issue 4 Pages 413-419
Maria Dolores Luque de Castro and Miguel Valc&aacute;rcel Cases

Abstract: In flow injection analysis (f.i.a.), the different characteristics resulting from the relative location of several detectors allows a sub-classification into either series or parallel configuration. Detection by potentiometric techniques is common in the series mode, and sequential ion-selective electrodes permit the simultaneous determination of several species, such as alkali or alkaline-earth metals, in serum. With the detectors in parallel, consideration is given to single-injection operation, with splitting of the sample, simultaneous multiple injection and zone sampling. Simultaneous determinations with use of a single detector are discussed in terms of sequential injection, stream-splitting with two cells aligned in the same optical path, with use of a pH gradient or f.i.a., and ion-exchange association. Examples of determinations are given; thus, with ion exchange, Zn and Cd in the range 10 to 100 and 20 to 200 ng mL-1, respectively, can be determined at a rate of 3 min per sample. Methods of f.i.a. based on differential kinetics are fully described, and difficulties inherent in this methodology are mentioned.
Blood Serum Ion exchange Electrode Potentiometry Simultaneous analysis General Gradient technique Kinetic Merging zones Reactor Review Stopped-flow Zone sampling pH gradient

"Open Thin Layer Cell - A Flow-through Electrode For Potentiometric Stripping Analysis"
Analyst 1987 Volume 112, Issue 2 Pages 133-136
Wolfgang Frenzel and Gerhard Schulze

Abstract: An electrochemical flow-through cell is described that is substantially different from all conventional cells. It has an open structure and is made from a piece of Plexiglass that contains the working and auxiliary electrodes. The flow channel is replaced by a strip of filter paper, which adheres to the cell body and covers the inlet hole and both electrodes. The carrier solution is therefore precisely directed along the filter strip, which dips into the waste reservoir containing the SCE.Potentiometric stripping analysis (PSA) was used to evaluate the performance characteristics of the cell in terms of flow-rate, injection volume and carrier composition. Linear calibration graphs were obtained in two concentration ranges (10-500 µg l-1 and 1-10 mg l-1) for Cd, Pb and Cu under slightly different experimental conditions. The practical advantages and the long-time response stability of the cell were demonstrated by the PSA determination of Zn in tap water. In the range 0.1-20 mg l-1 a sample throughput of 120 h-1 is obtainable with a reproducibility better than 5%.
Water Electrode Potentiometric stripping analysis Tecator

"Characterization Of Mercury Deposition On A Platinum Thin-ring Ultra-microelectrode And Its Application To Flow Injection Anodic-stripping Voltammetry"
Analyst 1989 Volume 114, Issue 9 Pages 1039-1042
Eddie Boon-Tat Tay, Soo-Beng Khoo and Sow-Wai Loh

Abstract: Mercury was deposited on a thin-ring (0.345 cm x 0.2 µm) Pt ultra-microelectrode (Anal. Abstr., 1987, 49, 5J27), and the deposition was characterized. The prepared electrode was suitable for anodic-stripping voltammetry of Cu, Pb, Cd and Zn after deposition from solution at -1.0, -1.0, -1.0 and -1.2 V, respectively. The calibration graphs were rectilinear for 0.1 to 10 µM, and coefficient of variation were 0.8 to 3.5%. Results were similar to those obtained with carbon-fiber-based microelectrodes. The prepared electrodes were susceptible to inter-metallic interference as with other electrodes used in anodic-stripping voltammetry.
Voltammetry Electrode Interferences

"Oxygen Removal In Flow Injection Anodic-stripping Voltammetry"
Analyst 1989 Volume 114, Issue 10 Pages 1271-1273
Eddie Boon-Tat Tay, Soo-Beng Khoo and Siau-Gek Ang

Abstract: The method involves use a new flow cell (illustrated) and a six-way valve. A Hg-film electrode is formed by deposition on vitreous carbon, in the presence of O, at -1.0 V for 30 s, and the sample solution is then passed through the cell for deposition of metals at -0.8 V. After deposition, the sample solution is replaced by the stripping solution (0.1 M Na acetate buffer, pH 4.5), which is purged with N to remove O. The metals are determined by anodic-stripping voltammetry by scanning at 10 mV s-1 from -0.8 to 0 V. The method was applied in the determination of Cu, Pb and Cd in seawater. The corresponding limits of detection were 1.2, 0.8 and 0.75 nM with a flow rate of 3.1 mL min-1 and deposition for 3 min. The coefficient of variation were 5% for 5 nM and 2% for 0.5 µM.
Sea Voltammetry Electrode Valve Buffer Detection limit Flowcell

"Cadmium - Toxicology And Analysis - A Review"
Analyst 1991 Volume 116, Issue 6 Pages 549-568
Kevin Robards and Paul Worsfold

Abstract: A review is presented, with 593 references, of monitoring procedures, sample preparation and quantification of Cd in various samples, including environmental and biological materials and food.
HPLC Ion exchange Neutron activation analysis Spectrophotometry Voltammetry Preconcentration Review

"Separation And Determination Of Trace Amounts Of Zinc And Cadmium By Online Enrichment In Flow Injection Flame Atomic Absorption Spectrometry"
Analyst 1991 Volume 116, Issue 8 Pages 825-830
Rajesh Purohit and Surekha Devi

Abstract: The preparation and characterization of tercopolymeric chelating resins, incorporating quinolin-8-ol and resorcinol - hydroquinone, are described. The resins were applied for pre-concentration. in the determination of Zn and Cd by flow injection flame AAS. A column (2 cm x 2 mm) containing the resin was incorporated into a flow injection manifold (described with diagram). Sample solution was passed through the column and Zn and Cd were eluted (3 mL min-1) with 1 M HNO3 (50 µL). Zinc and Cd were determined at 213.9 and 228.8 nm, respectively, by flame AAS. The detection limits were 1 ng mL-1. The average coefficient of variation (n = 6) were between 1.5 and 1.9% with the various resins.
Spectrophotometry Chelation Column Preconcentration Resin 8-Hydroxyquinoline

"Tubular Potentiometric Detector For Flow Injection Based On Homogeneous Crystalline Membranes Sensitive To Copper, Cadmium And Lead"
Analyst 1994 Volume 119, Issue 2 Pages 209-212
Isabel M. P. L. V. O. Ferreira and Jos&eacute; L. F. C. Lima

Abstract: Homogenous crystalline membranes were pressed from ~0.25 g of MS/Ag2S (M = Cu, Cd or Pb) mixtures at 19 000 kg/cm2, and fabricated into tubular potentiometric detectors (TPD). The internal conductor of a shielded cable was fixed to a small silver plate to which a portion of the membrane was attached with epoxy resin. After baking overnight at 70°C, the device was housed in a perspex cylinder which was filled with a non-conductive epoxy resin. This unit was hardened by baking and a hole was drilled lengthwise through the middle of the sensor membrane. The performance of the resulting TPD was compared with conventional ISE prepared from the same membranes in FIA (details given). Using the TPD, response times ranged from 0.4-4.8 s and RSD were 0.4%, 1% and 0.9% for Cu, Cd and Pb, respectively. The lower limit of linear response 50 µM-Cu and 0.2 mM Cd and -Pb. Detection limits were not determined. The overall performance of the two detector geometry types were broadly similar.
Potentiometry Electrode

"Spectrofluorimetric Detection Of Zinc And Cadmium With 8-(benzenesulfonamido)-quinoline Immobilized On A Polymeric Matrix"
Analyst 1994 Volume 119, Issue 6 Pages 1225-1228
Ramon Compa&ntilde;&oacute;, Raul Ferrer, Jacinto Guiteras and M. Dolors Prat

Abstract: 8-(Benzenesulfonamido)quinoline (BSQ) immobilized on XAD-7 resin (10 µmol of BSQ/g of resin) was packed into a 10 mm flow cell (diagram given), which was placed in a fluorimeter and used in a flow injection system for the determination of Cd and Zn. Sample (100 µL) containing 0.5-50 ng of metal, was injected into a carrier stream (0.3 ml/min) of 0.1 M Tris hydrochloride buffer of pH 9 containing 0.2 M NaCl. After mixing, the solution passed to the flow cell containing the immobilized BSQ maintained at 20°C and the metal-BSQ complex formed was detected fluorimetrically at 492 and 493 nm for Zn and Cd, respectively (excitation at 370 and 368 nm, respectively). Calibration graphs were linear from 5-500 µg/l of Zn and from 6-500 µg/l of Cd; the corresponding detection limits and RSD (n = 7) were 1.6 and 1.9 µg/ml. The RSD (n = 15) were 1.2-1.7%.
Polymer Fluorescence Complexation Solid phase detection

"Determination Of Trace Amounts Of Cadmium In A Hydrometallurgical Zinc Refining Process Stream By A Flow Injection Method With Online Preconcentration And Spectrophotometric Detection"
Analyst 1996 Volume 121, Issue 1 Pages 7-11
Yutaka Hayashibe and Yasumasa Sayama

Abstract: Zinc electrolyte (350 µL) was injected into a carrier stream (1 ml/min) of 0.1 M KI and passed through a column (10 cm x 1 mm i.d.) of Bio-Rad AG1-X8 anion-exchange resin (100-200 mesh, chloride form). At 220 s after sample injection, the cadmium-iodo complex was eluted from the column with a stream (1 ml/min) of 1 M HNO3. The eluate was merged with a stream (1.5 ml/min) containing a mixture of 0.002% Cadion/0.1 M KOH/0.1% Triton X-100 (reagent solution) and 17 mM trisodium citrate/8.8 mM potassium sodium tartrate/2 M KOH (masking agent solution) and the absorbance of the Cd-Cadion complex was measured at 480 nm. A multiple sample injection method, in which 350 µL portions of the sample were repeatedly injected into the carrier stream at 30 s intervals, was also applied. For the single injection method, the calibration graph was linear for 0.05-2 µg/ml Cd, the detection limit was 0.028 µg/ml, the RSD (n = 5) was 5% and the throughput was six samples/h. For the multiple injection method (50 injections), the calibration graph was linear for 2-40 ng/ml Cd, the detection limit was 0.83 ng/ml, the RSD (n = 5) was 10% and the throughput was two samples/h. The method was also applied to river water.
River Zinc Spectrophotometry Preconcentration Triton X Surfactant

"Determination Of Cadmium In Environmental Samples By Hydride Generation With In Situ Concentration And Atomic Absorption Detection"
Analyst 1997 Volume 122, Issue 4 Pages 331-336
Henryk Matusiewicz, Mariusz Kopras and Ralph E. Sturgeon

Abstract: A continuous-flow AAS system for Cd determination is described. A Cd solution acidified with HCl was mixed with 1 µg/ml Co and 0.5% thiourea (and also with 0.01 M didodecyldimethyl-ammonium bromide for reaction with KBH4) and diluted to 1 mL with water. The resulting solution was aspirated at a flow rate of 1 ml/min into a continuous-flow system and merged with a stream of either 2% NaBH4 or 4% KBH4 at a flow rate of 1 ml/min. The mixture was passed through a reaction cell/gas-liquid separator maintained at 50°C and the volatile Cd species evolved were carried by an Ar stream on to the inner wall of a GF for in situ pre-concentration at 200°C. Cd analysis was by ET AAS with atomization at 1800°C for 3 s; detection was at at 228.8 nm. The detection limit was 10 ng/l Cd with KBH4 as reagent. RSD were 10^-14% (n = 10). The method was applied to several environmental and biological CRM. The results obtained agreed with the certified values.
Environmental NIES 1 Estuarine Sea NRCC CASS-3 NRCC PACS-1 NRCC TORT-2 Hepatopancreas NIST 2710 Plant Spectrophotometry Heated reaction Volatile generation Reference material Phase separator Preconcentration Volatile generation

"Fully Automatic Online Separation Preconcentration System For Electrothermal Atomic Absorption Spectrometry: Determination Of Cadmium And Lead In Seawater"
Analyst 1997 Volume 122, Issue 7 Pages 679-684
Facundo M. Fern&aacute;ndez, Jorge D. Stripeikis, Mabel B. Tudino and Osvaldo E. Troccoli

Abstract: A fully automated system for analyte separation and pre-concentration prior to ET AAS determination is described. Preconcentration is performed on a chelating resin microcolumn (Chelex-100) placed in the injection tip of the graphite furnace autosampler. A time-based computer-controlled flow injection manifold is used for column conditioning, pre-concentration and washing steps. Elution is performed in a single step by the programmable graphite furnace autosampler; both complete and partial injection of the eluate into the graphite furnace for ET AAS analysis are possible. Diagrams of the manifold used, illustrating the sequence of operations involved, are given. The system was used to determine Cd and Pb in seawater. Detection limits of 0.9 and 8 ng/l were obtained for Cd and Pb, respectively. The RSD (n = 10 or 15) were 2.7-4%.
Sea Sample preparation Spectrophotometry Automation Chelation Chelex Column Detection limit Preconcentration Computer

"Determination Of Cadmium In Mussels By Flame Atomic Absorption Spectrometry With Preconcentration On A Chelating Resin In A Flow Injection System"
Analyst 1998 Volume 123, Issue 1 Pages 105-108
M. F. Enr&iacute;quez-Dom&iacute;nguez, M. C. Yebra-Biurrun and M. P. Bermejo-Barrera

Abstract: A flow injection pre-concentration system with a chelating resin was developed to determine trace and ultratrace amounts of cadmium in mussels by flame atomic absorption spectrometry. The metal was pre-concentrated on a microcolumn packed with poly(aminophosphonic acid) resin and eluted with dilute hydrochloric acid into the nebulizer-burner system of an atomic absorption spectrometer. A pre-concentration factor of 16-47, equivalent to 3.4-10 mL of sample, was achieved by using a time-based technique. The detection limit (3s) in the sample digest was 0.56 µg/L-1 for a sample volume of 3.4 mL. The precision (relative standard deviation) obtained for different amounts of cadmium was in the range 1.4-6.6% at the 1-20 µg/L-1 level. Chem. and flow variables, and other figures of merit of the proposed methodology, were studied. The method demonstrates high tolerance to interferences, and the anal. results obtained for a certified reference material were in good agreement with the certified value. The method was successfully applied to the determination of trace amounts of cadmium in mussel samples from estuaries in Galicia (Spain).
Mussel Spectrophotometry Chelation Preconcentration Resin Polyaminophosphonic acid Reference material Optimization Interferences

"Automation In Element Preconcentration With Chelating Ion Exchangers"
J. Anal. At. Spectrom. 1987 Volume 2, Issue 6 Pages 611-614
G&uuml;nter Knapp, Kurt M&uuml;ller, Martin Strunz and Wolfhard Wegscheider

Abstract: A microprocessor controlled pre-concentration system that permits the automated off-line pre-concentration of several samples at the same time is described. Trace elements pre-concentrated from sample volumes of up to several hundred millilitres can be eluted by 5 mL of 2 M nitric acid. It is therefore possible to achieve pre-concentration factors of up to 100. In contrast to FIA methods all ICP-AE spectrometers can be used for the measurements. Four different chelating ion-exchange materials, Chelex 100, oxine cellulose, CPPI resin and Hyphan cellulose, were compared. Trace elements were enriched from concentrated salt solutions and from NBS standard reference materials following decomposition in the High Pressure Asher. After elution the elements were measured by ICP-AES (Plasma II) and by graphite furnace AAS (HGA-500/Zeeman 5000). Under the conditions tested, Chelex 100, the oxine cellulose and the CPPI resin can be employed satisfactorily in the automated pre-concentration of a number of elements.
Biological Environmental Rice Flour Water Ion exchange Spectrophotometry Spectrophotometry Chelation Computer Preconcentration

"High-efficiency Low-sample-consumption Online Ion-exchange Preconcentration System For Flow Injection Flame Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1989 Volume 4, Issue 6 Pages 543-546
Zhaolun Fang and Bernhard Welz

Abstract: The cited system was used for determination of heavy metals. Only 1.6 mL of sample solution was required for analysis, 120 samples h-1 could be analyzed, and enrichment factors of 25 to 31 were achieved for Cu, Cd and Pb. The coefficient of variation were 1.2 to 2.8%; e.g., for 100 µg L-1 of Cu the coefficient of variation was 1.5% (n = 81). The CPG/8-Q ion exchanger was used, and conical columns, short, small-bore conduits and three-dimensional disoriented reactors were used to limit the dispersion of the eluted sample zone. Low elution flow rates and high nebulizer uptake rates were used to improve nebulization efficiency. Application of the method in analysis of seawater is discussed.
Sea Spectrophotometry Small sample Resin Column Dispersion Nebulizer Preconcentration

"Flow Injection Online Separation And Preconcentration For Electrothermal Atomic Absorption Spectrometry. 1. Determination Of Ultra-trace Amounts Of Cadmium, Copper, Lead And Nickel In Water Samples"
J. Anal. At. Spectrom. 1991 Volume 6, Issue 4 Pages 295-300
Michael Sperling, Xuefeng Yin and Bernhard Welz

Abstract: A micro-scale flow injection pre-concentration. system combined online with electrothermal AAS results in a powerful integrated system. Improved detection limits and low contamination are achieved by the system. The applicability of this technique in the determination of Cd, Cu, Pb and Ni in water is demonstrated. Detection limits for Cd, Pb, Cu and Ni were 0.8, 6.5, 17 and 36 ng l-1. The selectivity of the dithiocarbamate-C18 reversed-phase system allows interference-free determination of ultra-trace amounts of elements in natural waters to be undertaken. High flexibility and only a slight reduction in precision is provided by time-based loading and subsampling.
Environmental Spectrophotometry Sample preparation C18 Extraction Interferences Preconcentration Silica Ultratrace

"Rapid Stopped-flow Microwave Digestion System"
J. Anal. At. Spectrom. 1991 Volume 6, Issue 6 Pages 457-463
Vassili Karanassios, F. H. Li, B. Liu and Eric D. Salin

Abstract: A prototype system for stopped-flow microwave assisted wet digestions has been developed. A coiled Teflon PFA tube serves both as a sample container and as a digestion vessel. A sample plug, consisting of a water slurry mixed with an acid mixture, is pumped into the coil. Sample flow is stopped, the coiled tube is sealed (by closing an input and an output valve) and microwave power is applied for 2 min for digestion of the sample. Methodology was developed using powdered botanical reference samples and was tested with powdered botanical and biological reference materials. The digests were analyzed by inductively coupled plasma atomic emission spectrometry. In addition to comparisons with certified values, the results were compared with those obtained by conventional open-vessel hot-plate digestions, by open-vessel microwave digestions and by digestions taking 32 min by using the coiled tube system. Precise, and in many instances, quantitative digestions were obtained using a net digestion time of 2 min. Elemental recoveries were sample type and digestion time dependent and were found to be comparable with, and sometimes, superior to those obtained when using a 3 h long hot-plate digestion. In this preliminary study, characteristics, limitations and future directions are discussed.
Geological Plant Sample preparation Microwave Online digestion Stopped-flow

"Preconcentration And Inductively Coupled Plasma Atomic Emission Spectrometric Determination Of Metal Ions With Online Chelating Ion Exchange"
J. Anal. At. Spectrom. 1992 Volume 7, Issue 1 Pages 19-22
Valerio Porta, Corrado Sarzanini, Ornella Abollino, Edoardo Mentasti and Enzo Carlini

Abstract: An online pre-concentration method utilizing a microcolumn of XAD-2 resin functionalized with 1-(2-thiazolylazo)-2-naphthol was developed. Preconcentration factors of 125 were obtained for injection times of 5 min. The detection limit ranged between 2 for manganese and 40 ng/L for nickel. The resin was used to pre-concentrate Cd, Cu, Fe, Mn, Ni, and Zn from river water and Antarctic seawater (Ross Bay) prior to their determination by inductively coupled plasma atomic emission spectrometry. The precision of the technique is ~10% relative standard deviation at concentrations below the µg/L level and 5% for higher concentrations.
River Sea Ion exchange Spectrophotometry Preconcentration Amberlite Resin Chelation

"Flow Injection Online Coprecipitation Preconcentration For Electrothermal Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1992 Volume 7, Issue 2 Pages 439-446
Zhaolun Fang and Liping Dong

Abstract: A flow injection pre-concentration system was synchronously coupled to an electrothermal AAS instrument for the determination of Cd and Ni in whole blood. Samples (1 ml) were digested with HNO3 - HClO4 (5:1) at 170°C to near dryness and the residue was mixed with Fe(II) solution (10 g l-1) and 1% sulfosalicylic acid solution The solution was injected into the flow injection system and mixed with a stream (0.4 mL min-1) of aqueous 0.25% hexamethyleneammonium - hexamethylenedithiocarbamate (I). Cadmium and Ni were co-precipitated with the Fe(II) - I complex on the walls of a PTFE knotted reactor. The resulting precipitate was dissolved in isobutylmethylketone before introduction on to the platform of a graphite furnace carried by a stream of I. Electrothermal AAS was carried out in parallel with the pre-concentration. of the next sample. The detection limits were 3 and 2 ng L-1 for Cd and Ni, respectively, with coefficient of variation of 5.9 and 6.0% for 20 ng L-1 and 1.5 µg L-1 of Cd and Ni, respectively. A flow injection online co-precipitation system has been synchronously coupled to an electrothermal atomic absorption spectrometric system for the determination of trace amounts of heavy metals in whole blood digests. Cadmium and nickel in the digest were co-precipitated with the iron(II)-hexamethylenedithiocarbamate (HMDTC) complex on the walls of a knotted reactor without using a filter. The ppt. was dissolved in 60 µL of iso-Bu Me ketone and stored in a poly(tetrafluoroethylene) tube before introduction onto the platform of a graphite furnace carried by a stream of HMDTC reagent. Electrothermal atomic absorption spectrometric determination of the analyte was performed in parallel with the pre-concentration. of the next sample. Enrichment factors of 16 and 8 were obtained for cadmium and nickel, respectively, using 20 and 40 s ppt. collection times, at a sample flow-rate of 3 mL min-1 for cadmium and 2 mL min-1 for nickel. The detection limits (3s) were 0.003 and 0.02 µg L-1 for cadmium and nickel, respectively, and the precisions were 5.9% relative standard deviation (RSD) at the 0.02 µg L-1 level for cadmium, and 6.0% RSD at the 1.5 µg L-1 level for nickel. Recoveries of cadmium and nickel in blood digests were 103 and 106%, respectively
Whole Sample preparation Spectrophotometry Preconcentration Coprecipitation Knotted reactor Organic solvent

"Determination Of Trace Metals In Uranium Oxide By Inductively Coupled Plasma Mass Spectrometry Combined With Online Solvent Extraction"
J. Anal. At. Spectrom. 1992 Volume 7, Issue 3 Pages 565-569
S. Vijayalakshmi, R. Krishna Prabhu, T. R. Mahalingam and C. K. Mathews

Abstract: An online solvent extraction technique for the determination of trace elements in uranium by inductively coupled plasma mass spectrometry is described. An aqueous solution containing uranium (2% m/v) in 1 mol L-1 nitric acid and an organic solvent that can effectively ext. uranium, viz., trioctylphosphine oxide in cyclohexane (0.2 mol L-1), are pumped alternately through a poly(tetrafluoroethylene) (PTFE) tube where they mix thoroughly. The organic phase containing the extd. uranium is removed online by allowing the solution to pass through a microporous PTFE tube which, being hydrophobic, selectively allows the organic phase to permeate through its walls. This technique facilitates rapid and sensitive determination of trace elements in uranium with detection levels in the range 1-45 ppb for La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb, Ag, Ba, Cd, Co, Cr, Cu, In, Li, Mn, Ni, Pb, Sr, Ti, V and Y, 0.1 ppm for Al and 0.5 ppm for Fe. flow rate of about 4 mL min-1 was used.
Inorganic compound Mass spectrometry Sample preparation Solvent extraction Teflon membrane

"Determination Of Copper And Cadmium Using An Online Anodic Stripping Voltammetry Flow Cell With Detection By Inductively Coupled Plasma Mass Spectrometry"
J. Anal. At. Spectrom. 1992 Volume 7, Issue 7 Pages 1131-1137
Jack R. Pretty, Elmo A. Blubaugh, E. Hywel Evans, Joseph A. Caruso and Timothy M. Davidson

Abstract: An online anodic stripping voltammetry flow system was used to deposit copper and cadmium from National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 2670 Toxic Metals in Freeze-Dried Urine at a working electrode, with release of the analyte for detection by inductively coupled plasma mass spectrometry after the sample matrix was cleared from the cell. Recoveries determined against calibration graphs and by the method of standard additions were 94-115% for copper and 89-97% for cadmium. Spike recoveries for both analytes ranged from 92-106%. Elimination of the sodium-based polyatomic species at m/z = 62 and 63 remains highly efficient for up to 1 x 10^4 µg mL-1 of sodium, whereas the use of dilute nitric acid as electrolyte gives far superior results for copper than those previously reported. Recent improvements in the system manifold design are discussed.
NIST 2670 Urine Voltammetry Mass spectrometry Electrochemical stripping Preconcentration Reference material Interferences Optimization Flowcell

"Performance Of A Modular Thermospray Interface For Signal Enhancement In Flame Atomic Absorption Spectrometry Coupled Online To Flow Injection [analysis] Or Liquid Chromatography"
J. Anal. At. Spectrom. 1993 Volume 8, Issue 4 Pages 659-664
Erik H. Larsen and Jean-Simon Blais

Abstract: A simple and inexpensive thermospray interface is described that was connected to a flame AAS system without modification of the nebulizer and burner assembly. Details are provided of its construction and performance characteristics. The interface provided improved signal-noise and signal enhancement in a flow injection - AAS system with rectilinear calibration and detection limits of 1.9 ng of Cd, 8.5 ng of Cu and 27 ng of Pb. The use of the interface to couple HPLC to AAS was demonstrated for the determination of metallothioneins in biological samples.
Biological Spectrophotometry Low cost Interface Apparatus Nebulizer Signal enhancement Signal to noise ratio

"Ultratrace Determination Of Cadmium By Vapor Generation Atomic-fluorescence Spectrometry"
J. Anal. At. Spectrom. 1993 Volume 8, Issue 5 Pages 723-729
Les Ebdon, Phillip Goodall, Steve J. Hill, Peter B. Stockwell and K. Clive Thompson

Abstract: A commercial hydride generator was used with continuous-flow methodology for generation of volatile Cd-containing species with use of sodium tetraethylborate as reagent. The system was interfaced to an atomic absorption spectrometer and an atomic-fluorescence spectrometer to enable detection of the volatiles by these techniques. Optimization of AFS conditions, in particular purge gas flow rate, flame composition (H fuel gas flow rate) and reagent concentration, resulted in a detection limit of 20 ng/l. The method was applied to determination of Cd in three reference materials and in potable water; full test recoveries from potable water were 0.5-5 ng/ml. Citrate could be used to mask interference from some transition metals, e.g., Ni.
Water Fluorescence Spectrophotometry Interferences Reference material Optimization Ultratrace

"Online Removal Of Interferences In The Analysis Of Biological Materials By Flow Injection Inductively Coupled Plasma Mass Spectrometry"
J. Anal. At. Spectrom. 1993 Volume 8, Issue 5 Pages 691-696
Les Ebdon, Andrew S. Fisher, Paul J. Worsfold, Helen Crews and Malcolm Baxter

Abstract: Interference trace metals Cd, Cu, Mn, Pb, V and Zn were removed by chelation with 0.1 g of iminodiacetate-based resin (Na+ form; 50-100 mesh) in a micro-column. The metals were eluted into the VG PlasmaQuad PQ2 spectrometer with 3 M HNO3 by a flow injection procedure. Test recoveries were nearly quantitative except for V (90%) and Zn (85%) and the limits of detection were 0.6-9.9 ng/ml, equivalent to 75-1800 pg of element. Results were tabulated for the determination of the cited elements in five reference materials. The method was not suitable for the determination of Cr.
Biological Mass spectrometry Interferences Reference material Iminodiacetate

"Generation Of Volatile Cadmium Species With Sodium Tetrahydroborate From Organized Media: Application To Cadmium Determination By Inductively Coupled Plasma Atomic-emission Spectrometry"
J. Anal. At. Spectrom. 1993 Volume 8, Issue 6 Pages 847-852
M. C. Vald&eacute;s-Hevia y Temprano, M. R. Fern&aacute;ndez de la Campa and Alfredo Sanz-Medel

Abstract: For the continuous-flow determination of Cd by hydride-generation ICP-AES, generation was with 4% NaBH4 in 0.1% NaOH as reagent (0.75 ml/min) in a micellar medium of 0.01 mM didodecyldimethylammonium bromide in 0.4 M HCl (0.75 ml/min) to aid separation. A r.f. plasma with forward power of 900 W and detection at 214.44 nm was used. Calibration graphs were rectilinear for 1 µg/ml of Cd with a detection limit of 1 ng/ml and RSD of 2.1% at 50 ng/ml of Cd. The method was applied to the determination of Cd in tea infusions containing 5.8-22 ng/ml of Cd.
Plant Sample preparation Spectrophotometry Volatile generation Micelle PPB Volatile generation

"Immobilized Cysteine As A Reagent For Preconcentration Of Trace Metals Prior To Determination By Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1993 Volume 8, Issue 7 Pages 1011-1014
Hayat A. M. Elmahadi and Gillian M. Greenway

Abstract: Trace metals were determined by AAS in a flow injection system (manifold illustrated) that provided online pre-concentration on glutaraldehyde-immobilized cysteine on controlled-pore glass. A Varian model AA75 atomic absorption spectrophotometer was used with an air-acetylene flame, and the immobilized cysteine was contained in a 5 cm x 2.5 mm column. Cu, Zn, Cd, Pb, Co and Hg were pre-concentrated with capacities of 7.86, 7.88, 12.48, 11.66, 5.50 and 6.06 mmol/g. The presence of other metals at 1 and 5 µg/ml produced no interference, but at 20 µg/ml there was some negative interference. Co was only poorly retained, and was displaced by the other cited metals, but not by Mg.
Spectrophotometry Immobilized reagent Preconcentration Controlled pore glass Interferences

"Online Flow Injection Cobalt-ammonium Pyrrolidin-1-yldithioformate Coprecipitation For Preconcentration Of Trace Amounts Of Metals In Waters With Simultaneous Determination By Inductively Coupled Plasma Atomic-emission Spectrometry"
J. Anal. At. Spectrom. 1994 Volume 9, Issue 7 Pages 779-784
Zhixia Zhuang, Xiaoru Wang, Pengyuan Yang, Chenlong Yang and Benli Huang

Abstract: Rain was adjusted to pH 3 with dilute HNO3 or ammonia solution and spiked with 20 µg/ml of Co(II) as coprecipitant. The mixture was pumped (3.3 ml/min) and merged with a stream (0.4 ml/min) of 2% ammonium pyrrolidin-1-yldithioformate. The precipitate was collected on a PTFE membrane, washed with methyl isobutyl ketone, dissolved in HNO3/H2O2 (1:1) and carried to the ICP nebulizer for determination of Cd, Cu, Fe, Ni, Pb and Zn. Detection limits were 0.2-1 µg/g. Recoveries were >93%. RSD (n = 6) were 1.9-5 %.
Rain Spectrophotometry Preconcentration Coprecipitation MIBK Teflon membrane

"Analytical Characteristics Of An Inductively Coupled Plasma Mass Spectrometer Coupled With A Thermospray Nebulization System"
J. Anal. At. Spectrom. 1995 Volume 10, Issue 9 Pages 575-581
Hans Vanhoe, Steven Saverwijns, Magali Parent, Luc Moens and Richard Dams

Abstract: The effects of different matrix salts and mineral acids on analyte ion signals in ICP-MS was evaluated using the thermospray (TS) sample introduction system of Vanhoe et al. (Ibid., 1994, 99, 815). The results were compared with two other sample introduction systems, the pneumatic nebulizer coupled with a spray chamber (the conventional arrangement; CA) and the same nebulizer coupled with the desolvating unit employed with the thermospray nebulizer. Studies were effected with a 10 µg/l multi-element solution of Be, Al, Sc, Co, In, Gd, Tl, Th and U in 0.14 M HNO3 containing 1-5000 mg/l of the matrix elements Na, Ca, P and S (ICP-MS operating conditions tabulated). Non-spectroscopic interferences from Na and Ca were more pronounced for the TS system than the CA but were almost the same for P and S. The TS system was used for the analysis of Cd and Pb in three environmental reference materials (Community Bureau of Reference (BCR) Certified Reference Materials 141R Soil- calcareous loam, 144R sewage sludge-domestic and 146R sewage sludge-industrial, following digestion with aqua regia (experimental details given). A sample flow injection system was used to eliminate memory effects. Results obtained with the TS system agreed more closely with certified values than those obtained with the CA system.
BCR 141 BCR 144 BCR 146 Sludge Loam Mass spectrometry Sample preparation Reference material Method comparison Interferences

"Online Separation And Sequential Determination Of Trace Amounts Of Heavy Metals In Biological Materials By Flow Injection Inductively Coupled Plasma Atomic-emission Spectrometry"
J. Anal. At. Spectrom. 1996 Volume 11, Issue 2 Pages 107-110
M. T. Siles Cordero, E. I. Vereda Alonso, A. Garc&iacute; de Torres and J. M. Cano Pav&oacute;n

Abstract: Certified biological reference materials were mineralized by reacting with 65% HNO3, heating under reflux until the cessation of nitrous fumes, adding 35% H2O2 and concentrating to remove HNO3. The mixture was neutralized with NaOH, adjusted to pH 3.6 with glycine/HCl buffer and 1 M NaClO4 was added. The resulting solution was mixed, at a T-shaped solvent segmentor in a FIA system, with a carrier solution of 1,5-bis(di-2-pyridyl)methylene thiocarbohydrazide in DMF/IBMK (1:1) and passed through an extractor coil (200 cm x 0.8 mm i.d.). The resulting solution was split at a phase separator and the organic phase filled the injection loop of the ICP-AES instrument. The sample was pushed into the cross-flow nebulizer by an IBMK/DMF (1:1) carrier solution and the emission signals were recorded (plasma type not given). Calibration graphs were linear for 10^-2000 ng/ml for Co and Cu and 20 to 2000 ng/ml for Zn and Cd with detection limits of 4.8, 1.1, 20.3 and 23 ng/ml, respectively. The corresponding RSD (n = 8) were 1.9, 1.2, 2.8 and 3.7%. The effects of foreign ions are discussed with S2- being the most serious interferent.
Biological material Spectrophotometry Interferences Reference material MIBK Phase separator

"Determination Of Copper, Cadmium And Lead In Biological Samples By Isotope-dilution Inductively Coupled Plasma Mass Spectrometry After Online Pretreatment By Anodic-stripping Voltammetry"
J. Anal. At. Spectrom. 1996 Volume 11, Issue 5 Pages 353-357
Tarn-Jiun Hwang and Shiuh-Jen Jiang

Abstract: Standard reference materials plus appropriate amounts of the corresponding enriched isotope solutions were digested with HNO3/H2O2 in a closed vessel by heating in a microwave oven. The digest was diluted with 0.1 M NH4NO3 as supporting electrolyte and a 2 mL portion was injected from a PTFE sample loop into the carrier stream (1.2 ml/min) of the supporting electrolyte in an FIA system. The stream was pumped through an anodic-stripping voltammetry flow cell constructed from a PTFE rod (details given) and equipped with a reticulated vitreous-carbon working electrode, an Ag/AgCl reference electrode and a Pt-wire counter electrode. A deposition potential of -1.2 V was applied to the working electrode for a preselected period, after which the carrier flow was stopped. The working electrode potential was changed to +0.2 V and 10 mM HNO3 (2 ml/min) was passed through the flow cell to elute the analytes for determination by isotope-dilution ICP-MS (operating conditions given). The effects of the sample and eluent flow rates and the presence of matrices were investigated. The detection limits for Cu, Cd and Pb were 70, 10 and 70 pg/ml, respectively. Calibration graphs were linear up to at least 200 ng/ml.
Biological material Mass spectrometry Reference material Electrochemical stripping Interferences

"Ultratrace Determination Of Cadmium By Atomic Absorption Spectrometry Using Hydride Generation With In Situ Preconcentration In A Palladium-coated Graphite Atomizer"
J. Anal. At. Spectrom. 1996 Volume 11, Issue 8 Pages 571-575
Heidi Goenaga Infante, Maria L. Fern&aacute;ndez S&aacute;nchez and Alfredo Sanz-Medel

Abstract: Cd sample was dissolved in 0.4 M HCl and 10 mM didodecyldimethylammonium bromide (DDAB) vesicles, the solution was pumped through a FIA system at 1.4 ml/min and the stream merged with a stream (1.4 ml/min) of 4% NaBH4 in 10 mM DDAB. The resultant stream was fed into the entrance of a grid nebulizer and the gaseous phase passed to the graphite tube of the AAS instrument using Ar as the carrier gas. The sample was ashed at 800°C and atomized at 1600°C with Pd as a modifier and the signal was recorded at 228.8 nm. The calibration graph was linear up to 1 µg/l with a detection limit of 60 ng/l for a 1.4 mL sample and 13 ng/l for a 7 mL sample. The RSD (n = 10) was 1.7% at 0.5 µg/l.
Spectrophotometry Preconcentration Ultratrace

"Use Of Flow Injection Cold Vapor Generation And Preconcentration On Coated Graphite Tubes For The Determination Of Cadmium In Seawater By Electrothermal Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1996 Volume 11, Issue 11 Pages 1081-1086
Pilar Bermejo-Barrera, Jorge Moreda-Pi&ntilde;eiro, Antonio Moreda-Pi&ntilde;eiro and Adela Bermejo-Barrera

Abstract: Seawater was collected in 100 mL glass bottles and acidified with 0.1 mL 16 M HNO3 to prevent adsorption of Cd(II) on the glass walls. Portions (9 ml) were treated with HCl and gallium(III) nitrate to give final concentrations of 0.25 M and 0.5 µg/ml of Ga in 10 mL. This solution (0.5 ml) was injected into the carrier, 0.25 M HCl, which was pumped into the generator at 9 ml/min for 30 s, together with 2% NaBH4 in 0.5% NaOH, pumped at 5 ml/min for 30 s. The CdH2 generated was transferred through a quartz tube (2 cm x 0.5 mm i.d.) to the integral platform of a pyrolytic graphite furnace tube with a stream of Ar (150 ml/min) for 30 s. The furnace tube had been coated with Ir (details given); at 20°C the CdH2 was rapidly adsorbed to the coating. The Cd was then atomized at 1300°C for 4 s without gas flow and measured at 228.8 nm. The Ga(III) gave the best catalytic yield of CdH2 of several cations tried. Calibration graphs (no ranges given) in the carrier solution or prepared from synthetic or real seawater by standard additions had similar slopes, indicating no matrix interference; the detection limit was 4 ng/l. At 0.25-0.5 ng/l the in batch RSD were 0.2-0.4% (n = 11). The method was applied to six seawater samples (0.04-1.2 µg/1) giving RSD of 1.6-4.2% (n = 4).
Sea Spectrophotometry Interferences Preconcentration Standard additions calibration

"Fullerene: A Sensitive And Selective Sorbent For The Continuous Preconcentration And Atomic Absorption Determination Of Cadmium"
J. Anal. At. Spectrom. 1997 Volume 12, Issue 4 Pages 453-457
Yaneira Petit de Pe&ntilde;a, Mercedes Gallego, Miguel Val&aacute;crcel

Abstract: The use is described, with diagrams of the flow injection manifold used, of a column of 80 mg of fullerene C60 for the separation and pre-concentration of Cd as its pyrrolidine-1-carbodithioate complex. The sample solution (6 ml) of 3-300 ng of Cd2+ in 0.1 M HNO3 is injected into a stream (0.3 ml/min) of 0.1% ammonium pyrrolidine-1-carbodithioate solution in aqueous 5% ethanol, and the resulting complex is adsorbed on the fullerene, from which it is subsequently eluted with 0.2 mL of IBMK for online flame AAS. This combination of fullerene and chelating agent is superior to other continuous-flow separation/pre-concentration systems. Other heavy metals are tolerated in 600-1000-fold concentrations with respect to Cd; also, the results for Cd in standard reference oyster tissue, porcine kidney and bovine liver showed that there is negligible interference from the decomposition products of these samples.
NIST 1566 NIST 1577 Kidney Sample preparation Spectrophotometry Sample preparation Preconcentration MIBK Reference material Interferences Extraction

"Determination Of Cadmium By Flow Injection Isotope-dilution Inductively Coupled Plasma Mass Spectrometry With Vapor-generation Sample Introduction"
J. Anal. At. Spectrom. 1997 Volume 12, Issue 5 Pages 579-584
TARN-JIUN HWANG and SHIUH-JEN JIANG

Abstract: The sample (0.1 ml) is injected into a carrier stream of 2% thiourea/0.0002% Co solution in 0.1 M HCl (4.8 ml/min), which then merges with a stream of 4% NaBH4 solution in 0.1 M NaOH (2.4 ml/min) for passage to a gas-liquid separator that consists essentially of a vessel (diagram presented), containing 120 glass beads (5 mm diameter), from which the Cd-containing vapor is carried to the ICP by a stream of Ar. Interference from MoO+ and ZrO+ is thereby alleviated. Sample-preparation procedures are described for sediments, urine and water, in which 111Cd is added as the tracer; the result is calculated by use of the equation proposed previously (Ibid., 1996, 11, 353). The detection limit is 26 pg/ml of Cd. Recoveries of 5 ng/ml of Cd added to standard refence waters were quantitative, and the results for standard reference freeze-dried urine and marine sediments agreed well with the certified values.
Urine Marine Environmental Mass spectrometry Mass spectrometry Detection limit Interferences Isotope ratio Reference material Glass beads Volatile generation Volatile generation

"Inductively Coupled Plasma-mass Spectrometry For Direct Multielement Analysis Of Diluted Human Blood And Serum"
J. Anal. At. Spectrom. 1997 Volume 12, Issue 9 Pages 1005-1009
EBBA BARANY, INGVAR A. BERGDAHL, ANDREJS SCH&Uuml;TZ, STAFFAN SKERFVING and AGNETA OSKARSSON

Abstract: A method for the inductively coupled plasma mass spectrometry (ICP-MS) multi-element analysis of diluted human blood and serum was used for the following elements: Co, Ni, Cu, Zn, Ga, Se, Rb, Mo, Ph, Pd, Cd, Sn, Sb, W, Pt, Hg, Tl and Pb. Sample pretreatment was a simple dilution (ten times for blood and five times for serum) with a solution containing 5 g L-1 of 25% ammonia, 0.5 g L-1 Triton X-100, and 0.5 g L-1 EDTA in Millipore water. In and Sc were used as internal standards. For sample introduction a flow injection type technique (based on time instead of volume) was used. The determinations mere carried out first in a peak-jumping mode for selected masses, and then in a scanning mode. Each determination of a preparation took 75 s. The results for reference samples agreed with recommended or certified values for Co, Cu, Zn, Rb, Cd, Tl and Pb in blood, and for Rb, Mo and Cd in serum. For Ni and Hg in blood, and Cu and Zn in serum, the results agreed with one of two reference samples. The detection limits for all these elements (except for Tl) were sufficient for analysis of samples from the general population. On the other hand, the results for Se in blood, and for Co, Ni, Se, Sn and Hg in serum did not agree with recommended or certified values. No reference samples are available for Ga, Mo, Ph, Pd, Sn, Sb, W, or Pt in blood, or for Ga, Ph, Pd, W, Pt, or Pb in serum. Generally, the limits of detection for the elements in the latter group (below 0.15 µg l-1) are close to or above the levels present in the general population.
Whole Human Serum Human Mass spectrometry Multielement Interferences Timed injection Reference material Triton X Surfactant

"Determination Of Cadmium In Aqueous Media By Flow Injection Cold Vapor Atomic Absorption Spectrometry. Application To Natural Water Samples"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 4 Pages 295-300
Mar&iacute;a Liva Garrido, Riansares Mu&ntilde;oz-olivas and Carmen C&aacute;mara

Abstract: A simple, sensitive, and rapid flow injection system for Cd cold vapor generation coupled to atomic absorption spectrometry (FI-CV-AAS) was developed. A vesicular medium of didodecyldimethylammonium bromide (DDAM) was investigated in order to understand the possible mechanisms occurring in Cd cold vapor generation and the influence of this surfactant as a catalyst. Similar experiments in an aqueous medium were carried out with optimization of the physical and chemical parameters. Identical analysis characteristics such as linearity and precision, and similar detection limits (0.15 and 0.05 µg/L for DDAB and aqueous media, respectively), were found for both reaction media; hence, the use of surfactants was not necessary for Cd cold vapor generation. Validation of the method was carried out by determining the Cd content in several certified waters. The method was applied to the anal. of some natural waters by the standard additions calibration method.
Environmental Spectrophotometry Surfactant Reference material Standard additions calibration Optimization

"Determination Of Copper, Cadmium, Lead, Bismuth And Selenium(IV) In Sea-water By Electrothermal Vaporization Inductively Coupled Plasma Mass Spectrometry After Online Separation"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 5 Pages 363-369
Dirce Pozebon, Valderi L. Dressler and Adilson J. Curtius

Abstract: A procedure for the determination of Cu, Cd, Pb, Bi and Se(IV) in seawater by electrothermal vaporization inductively coupled plasma mass spectrometry, after online separation using a flow injection system, is proposed. Matrix separation and analyte pre-concentration. was accomplished by retention of the analytes complexed with the ammonium salt of O,O-diethyldithiophosphoric acid on C18 immobilized on silica in a minicolumn coupled directly to the autosampler arm of the vaporizer. The methanol used as eluent was vaporized after being automatically injected into the graphite tube, prior to the vaporization of the analytes. The conditions for the online complexation and separation as well as the vaporizer temperature program were optimized. The recoveries from seawater were 90-110%. The accuracy of the method was tested by the anal. of 2 certified seawaters, CASS-3 and NASS-4, from the National Research Council of Canada. The concentration. of Bi in these seawaters was below the method detection limit. The relative standard deviation was <10% (n=6). The throughput was 22 samples/h and the volume of sample consumed was only 2.3 mL. Tl and As(III) were also separated but their complexation in seawater was not efficient.
Sea NRCC CASS-3 NRCC NASS-4 Mass spectrometry Ion pair extraction C18 Silica Preconcentration Reference material

"Determination Of Copper, Cadmium, Manganese, And Lead In Saline Water With Flow Injection And Atom Trapping Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 7 Pages 631-634
Lyndon A. Ellis and David J. Roberts

Abstract: A flow injection device has been developed to sep. Cu, Cd, Mn and Pb from a solution of sodium chloride, thus minimizing interference and enabling their accurate determination in high salinity waters such as sea- or estuary water. Micro-columns of Chelex 100 resin were used and parameters of ammonium acetate buffer concentration, pH and the concentration. of a buffer flush have been optimized. Close to 100% recovery of the transition elements and 99.8% exclusion of sodium chloride was achieved. Atom trapping atomic absorption spectrometry (ATAAS) was used as the detection technique to determine concentrations. of the four elements at four sites on the Severn Estuary. In addition, a water cut-off device has been incorporated to improve the safety of the AT app.
Estuarine Sea Spectrophotometry Interferences Chelex Buffer

"Vesicle-assisted Determination Of Ultratrace Amounts Of Cadmium In Urine By Electrothermal Atomic Absorption Spectrometry And Inductively Coupled Plasma Mass Spectrometry"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 9 Pages 899-903
Heidi Goenaga Infante, Maria L. Fern&aacute;ndez S&aacute;nchez and Alfredo Sanz-medel

Abstract: Two methods for the determination of ultratrace amounts of Cd, based on vesicular hydride generation, including in situ trapping electrothermal atomic absorption spectrometry (ETAAS) and inductively coupled plasma mass spectrometry (ICP-MS), are described and compared for Cd determination in urine. The human urine samples are diluted 1 + 1 with ultrapure water and no other sample pre-treatment is necessary. Thus, the risk of contamination at basal or 'normal' metal levels in urine is minimized. Using flow injection hydride generation ICP-MS (FI-HG-ICP-MS), the detection limits observed for Cd in water and urine (50 µL sample volume) were 3.5 and 7 pg, respectively, the observed relative standard deviation for ten replicate analyzes of 50 µL of a 5 µg L-1 aqueous CD solution was ±3.2%. In situ trapping allows pre-concentration. in the graphite tube; by pre-concentrating. 1.4 mL of urine the detection limit achieved by ETAAS was 10 ng L-1 (14 pg, abs.). The use of silicone as an antifoam agent for vesicular cadmium hydride generation allowed a throughput of about 20 samples h-1 by FI-HG-ICP-MS detection. The concentration. of Cd in human urine was evaluated directly by aqueous standard calibration as no matrix interferences were observed for both methods under study. NIST SRM 2670 Toxic Metals in Freeze-Dried Urine was analyzed by the two methods with excellent results. The accuracy of the results was demonstrated in two ways because the reported values for the SRM agreed well with the results obtained using either of the two methods under investigation.
Urine NIST 2670 Spectrophotometry Mass spectrometry Reference material Interferences Method comparison Vesicle

"Interference Removal For Cadmium Determination In Waste Water And Sewage Sludge By Flow Injection Cold Vapor Generation Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 10 Pages 1145-1149
Mar&iacute;a Liva Garrido, Riansares Mu&ntilde;oz-olivas and Carmen C&aacute;mara

Abstract: Cold vapor generation coupled to atomic absorption spectrometry using flow injection (FI-CVAAS) was evaluated as a rapid and simple method for the determination of Cd in wastewater and sewage sludge. Wastewater samples did not need any pre-treatment prior to anal. The sewage sludge was digested in a high pressure microwave oven to ensure good solubilization of the samples. Some elements in the sample (Cu, Pb, Ni, Zn) showed important interferences in the FI-CVAAS method. Elimination of such interferences by adding KCN to the borohydride solution is discussed. Validation of the method was achieved by analyzing a sewage sludge sample used in an interlab. exercise organized by the Water Research Center, UK, and by comparing the results with those obtained by electrothermal atomic absorption spectrometry (ETAAS) using a graphite furnace. Wastewater and sewage sludge samples were analyzed by both FI-CVAAS and ETAAS methods.
Waste Sludge Spectrophotometry Sample preparation Interferences Method comparison

"Electroanalytical Flow System With An Oral Irrigating Appliance"
Anal. Chem. 1982 Volume 54, Issue 3 Pages 598-600
Joseph Wang

Abstract: The Water Pik appliance was interfaced with a stationary disk electrode and used as an electroanal. flow system. The interface resulted in an effective wall-jet electrode in which the solution stream flow from the tip nozzle perpendicularly onto the electrode surface. The system was illustrated by conventional scanning voltammetric, stopped-flow modulation voltammetric, and anodic-stripping voltammetric analyzes.
Electrode Electrode Potentiometry Voltammetry

"Potentiometric Stripping With Matrix Exchange Techniques In Flow Injection Analysis Of Heavy Metals In Groundwaters"
Anal. Chem. 1983 Volume 55, Issue 2 Pages 320-328
Alex Hu, Raymond E. Dessy, and Anders Graneli

Abstract: Potentiometric stripping analysis, in conjunction with flow injection analysis techniques, provides a convenient automated method for the determination of Cu, Cd, and Pb in groundwater. The theory behind the method is developed, and the hardware, software, and instrumentation required are presented. Application to real groundwater samples provides a comparison with previously described techniques. The separation of nearby oxidation peaks in potentiometric stripping analysis can be effected by matrix exchange techniques which involve plating in one environment and stripping in another. Flow injection analysis provides a convenient mechanism to automate this process. Heavy metals commonly found in groundwater, such as Pb, TI, Cd, Bi, Cu, and Sn, are studied by using this technique to explore the scope and limitations of the method.
Ground Potentiometry Potentiometric stripping analysis Theory

"Subtractive Anodic Stripping Voltammetry With Flow Injection Analysis"
Anal. Chem. 1984 Volume 56, Issue 2 Pages 156-159
Joseph Wang and Howard D. Dewald

Abstract: In this approach to subtractive anodic-stripping voltammetry, the analytical and background voltammograms are recorded while the sample and carrier solution, respectively, flow-through the detector; the carrier contribution is then subtracted. Effective correction for faradaic and non-faradaic background current contributions afforded a detection limit for Cd of ~0.14 ng (6 nM) with a 1-min deposition time. Non-deaerated samples could be used, owing to effective correction of the O reduction current. Simultaneous measurement of several trace metals at the ppb level by using 200 µL samples is possible and an injection rate of up to 24 samples h-1 can be achieved. Applications to multivitamin plus minerals tablets are described.
Pharmaceutical Voltammetry PPB Simultaneous analysis

"Sensitivity Enhancements For Flow Injection Analysis-inductively Coupled Plasma Atomic Emission Spectrometry Using An Online Preconcentrating Ion-exchange Column"
Anal. Chem. 1985 Volume 57, Issue 1 Pages 21-25
Steven D. Hartenstein, Jaromir Ruzicka, and Gary D. Christian

Abstract: The construction of 0.1 mL-capacity Chelex 100 ion-exchange columns for the pre-concentration of analyte elements is described. Separate, buffered (pH 9) samples are pumped through two parallel columns (to double the sampling frequency), and sequentially eluted directly into the nebulizer of the ICP by using a flow injection system. This method gives detection limits for simultaneous multi-element analysis that are a 20-fold improvement over those with conventional continuously aspirated systems for Ba, Be, Cd, Co, Cu, Mn, Ni and Pb. The sampling rate is 30 h-1.
Ion exchange Spectrophotometry Chelex Multielement Nebulizer Resin Preconcentration

"Inductively Coupled Plasma Mass Spectrometric Detection For Multielement Flow Injection Analysis And Elemental Speciation By Reversed-phase Liquid Chromatography"
Anal. Chem. 1986 Volume 58, Issue 12 Pages 2541-2548
Joseph J. Thompson and R. S. Houk

Abstract: The effluent from the HPLC column was converted into an aerosol by ultrasonic nebulization with desolvation for analysis on a Sciex ELAN model 250 ICP-MS instrument. Mobile phases used were methanolic solution of Na pentanesulfonate and tetrabutylammonium phosphate and the column (25 cm x 4.6 mm) contained Econosphere C18. Flow injection analysis coupled with ICP-MS was used to measure instrument response to a transient signal. Detection limits by flow injection analysis and by HPLC are reported for several elements. The separation and selective detection of As and Se species were shown; detection limits were ~0.1 ng (as the element) for all six species. Up to 15 elements could be determined in a single injection with multiple-ion monitoring. Isotope ratios measured on eluates containing Cd and Pb showed good accuracy, indicating that HPLC coupled with ICP-MS should allow speciation studies with stable tracer isotopes.
HPLC Mass spectrometry Spectrophotometry Speciation

"Automated Segmented-flow Electrochemical Analyser"
Anal. Chem. 1989 Volume 61, Issue 18 Pages 2102-2108
Palitha Jayaweera and Louis Ramaley

Abstract: An automated system combining segmented-flow analysis with pulse-voltammetric detection is described. Using a static-Hg-drop electrode in the reductive mode, multi-component determinations could be carried out at 100 samples h-1. The instrument can be programmed to perform square-wave voltammetry, staircase voltammetry and pulse voltammetry, all with scan reversal capability. Features include a simple flow system, complete computer control, an inline deoxygenator, stopped-flow analysis and signal averaging for reduced noise. Excellent rectilinearity, sensitivity and reproducibility were obtained; for metals such as Cd(II) and Pb(II) the detection limits were 6 and 8 ppb, respectively.
Voltammetry Electrode Computer Sensitivity Detection limit Stopped-flow PPB

"Automated Online Ion-exchange Trace Enrichment System With Flame Atomic Absorption Detection"
Anal. Chem. 1989 Volume 61, Issue 6 Pages 520-524
Yan Liu and James D. Ingle

Abstract: Chelex-100 chelating resin is used for enrichment of transition metals at trace concentrations In an automated flow system. The effects of column dimensions, resin particle size, and sample loading and eluting flow rates are studied. To avoid the problems of using a strong acid as the stripping reagent, complexing reagents like cysteine and ethylenedlaminetetraacetic acid are successfully employed to elute transition metals such as Cu, Cd, Mn, Zn, and Pb from small columns packed with Chelex-100 resin. To improve detection limits, the system can be configured for multiple injections of a given sample solution before the column is eluted. A stop-flow technique is developed to allow complete elution from Chelex-100 resin of transition metals that react more slowly with the stripping complexing ligands. The detection limits of the system with flame atomic absorption spectrophotometry are 0.09 pg/L for Cu and Cd and 0.08 pg/L for Mn with a 10 mL sample loop.
Ion exchange Spectrophotometry Stopped-flow Preconcentration Chelex

"Thermospray - Micro-atomizer Interface For The Determination Of Trace Cadmium And Cadmium Metallothioneins In Biological Samples With Flow Injection - And High Performance Liquid Chromatography - Atomic Absorption Spectrometry"
Anal. Chem. 1992 Volume 64, Issue 24 Pages 3197-3201
K. A. High, Richard Azani, A. F. Fazekas, Z. A. Chee, and J. S. Blais

Abstract: A description is given of a micro-atomization interface (made from quartz tubes) which is fuelled by hydrogen and can operate with 100% aqueous mobile phases used in HPLC. The system was optimized for the detection of Cd (total and bound soluble) in mussels and animal tissues, using flow injection AAS, or for the determination of metallothionein-bound Cd (isoforms I and II) in horse kidney, using HPLC - AAS. The detection limit obtained for Cd in the flow injection mode was ~2.2 orders of magnitude lower than that obtained with a conventional flame AAS detector, and 27-fold lower than that obtained by a thermospray-enhanced flame AAS system . Similar detection limits were obtained for the determination of metallothionein-bound Cd in the HPLC - AAS mode. A flexible thermospray-microatomization interface providing a high signal/noise ratio for flow injection atomic absorption spectrometry (AAS) and HPLC-AAS was designed and optimized for the determination of soluble Cd and Cd-metallothioneins (MTs). The interface, built from inexpensive quartz tubes, Swagelok fittings and thermoelectric wires, comprised 4 compartments: (1) a thermospray inlet; (2) a premixing tube in which the vaporized mobile phase was homogeneously mixed with preheated H; (3) a combustion chamber in which the fuel/sample mixture was mixed with O and pyrolyzed; and (4) a quartz tube (vapors retainer) mounted in the AAS analysis beam. This approach proved to more efficient than conventional flame AAS detection, due to the fact that the H/O flame (1900-2000°C), which pyrolysis mol. interferents to transparent CO2 and water vapors, is positioned remotely from the AAS optical beam. In this configuration, spectral interferences which are usually observed in flame and graphite furnace atomization were essentially eliminated. In flow injection (FI) mode, the response to Cd was linear from the limit of detection (71 pg) to 6 ng. The interface was optimized for the FI anal. of centrifuged mussel extracts, before and after ultrafiltration of the bound-Cd fraction on a 1000 MW cutoff membrane. During FI analyzes of these crude samples, matrix effect reduced the sensitivity by 13.2%, requiring calibration by standards addition Nonspecific absorption signal was not observed In HPLC-AAS mode, matrix effects in Cd-MTs chromatography bands were negligible. Cd-MTs from horse kidneys and mussels were determined with estimated limits of detection of 10^-40 ng (as protein).
Mussel Biological tissue Kidney HPLC Spectrophotometry Optimization Interface Speciation Interferences

"Adaptation Of Poly(tetrafluoroethylene) Tips To Mercury-drop Electrodes And Evaluation By Flow Injection Analysis"
Anal. Chem. 1993 Volume 65, Issue 4 Pages 500-503
Ivano G. R. Gutz, Lucio Angnes, and Jairo J. Pedrotti

Abstract: To overcome the effect of solution creeping between the Hg drop and the internal wall of the glass capillary in such electrodes, which can affect the area reproducibility of the drop as well as the drop time, a length (~3 cm) of PTFE tubing (0.051 mm i.d.; 0.35 mm o.d.) was heat-sealed at both ends and affixed by epoxy adhesive within a Tygon tube (1.6 mm o.d.). A 20-mm length of the combined tube was cut off and the orifice was conically widened to a depth of ~2 mm before gluing the tube within the drilled-out end (4-mm-deep cavity; 1.5 mm diameter) of a glass capillary tube; the lower end was then trimmed to a precise level. A dropping, hanging or static Hg electrode could easily be prepared from the tube assembly; a thick-walled PTFE tube could be used similarly and did not require enclosure within a Tygon reinforcing tube. A sessile static drop electrode prepared from thin-walled PTFE tubing was used as indicator, together with a Ag - AgCl electrode, in an amperometric flow cell in which a stainless steel needle acted as the cell outlet and the auxiliary electrode. This cell was applied in flow injection analysis for the determination of Cd in acidic medium and of As(III) in 0.1 M KOH medium. Repeated use of the same drop showed no degradation of response; for As, the linear dynamic range was 0.3 to 1500 ng.
Electrode Teflon membrane Linear dynamic range

"Use Of Saccharomyces Cerevisiae In Flow Injection Atomic Absorption Spectrometry For Trace Metal Preconcentration"
Anal. Chem. 1994 Volume 66, Issue 9 Pages 1462-1467
Angel Maquieira, Hayat A. M. Elmahadi, and Rosa Puchades

Abstract: Freeze-dried yeast was washed with CHCl3 and hot water, digested with 0.1 M HNO3/HClO4 (1:1) on a steam bath for 30 min. Ethanol was added dropwise and the resulting solution was diluted with water and adjusted to pH 7 with 2 M NaOH. The solution was treated with phosphate buffer solution of pH 5.5, 6.5, 7.5 or 8.5 before the addition of glutaraldehyde-treated controlled pore glass. Immobilization proceeded for 24 h at 4°C under N2, the glass was filtered off and air-dried. Immobilization was unsatisfactory at pH 8.5 and slightly less effective at pH 5.5 than at pH 6.5 or 7.5. Methacrylate columns (4 cm x 2.5 mm i.d.) of the yeast-treated glass were evaluated for the concentration of trace Cd, Zn, Cu(II), Pb(II) and Fe(III) ions from 0.1 M phosphate buffer of pH 6.5. The solution was applied to the column; elution was effected with acid and the metal ions were determined by AAS (details given). Zn and Cu(II) were eluted by 0.1 M HNO3, Pb(II) and Cd by 0.5 M HNO3 and Fe(II) by 0.5 M HClO4/HNO3 (1:1). Linear ranges extended up to 1500 ng/ml (Pb) and the detection limits were 0.1 (Zn) to 8.0 ng/ml (Pb). RSD (n = 10) were 2.6%. The method was used to determine Cu and Cd in sediment.
Environmental Spectrophotometry Preconcentration Controlled pore glass

"Metal Speciation By Supercritical-fluid Extraction With Online Detection By Atomic Absorption Spectrometry"
Anal. Chem. 1994 Volume 66, Issue 22 Pages 3900-3907
Jin Wang and William D. Marshall

Abstract: A silica flame-in-tube interface is described for the AAS detection of As, Cd, Cu, Mn, Pb, Se or Zn in the eluate from a SFE apparatus. It consisted of a heated optical tube placed within the optical beam of the spectrometer, a flame tube fitted with H2 and O2 gas entry ports and a sample introduction tube. The analyte metal in an aqueous medium was complexed in situ with tetrabutylammonium dibutyldithiocarbamate and the derivative was mobilized into supercritical CO2. The superheated extractor eluate was nebulized into the upper region of a diffuse flame in the interface flame tube and introduced into the optical tube for analysis. The optimal flame conditions were slightly reducing for aqueous and CO2 mobile phases but slightly oxidizing for a methanolic mobile phase. The detection limits of the metals were in the sub ng to low pg range when a standard was flow-injected into the mobile phase. The recoveries of 5 or 10 µg/ml of Cu, Mn and Pb were 92-94.4% with RSD of 0.1%; the RSD for the cumulative area under the AAS response curve was appreciably more variable. The differences in the rates of mobilization of analyte metal from different matrices was studied using fresh and freeze-dried bovine liver.
Liver Sample preparation Spectrophotometry Speciation Solvent extraction

"Immobilized Cyanobacteria For Online Trace Metal Enrichment By Flow Injection Atomic Absorption Spectrometry"
Anal. Chem. 1994 Volume 66, Issue 21 Pages 3632-3638
Angel Maquieira, Hayat A. M. Elmahadi, and Rosa Puchades

Abstract: Cyanobacteria (Spirulina platensis) immobilized on controlled pore glass pre-concentrate Cu(II), Zn(II), Cd(II), Pb(II), and Fe(III) from aqueous solution with high efficiency as ascertained using an online flow injection atomic absorption spectrometry system. The degree of metal binding depends on the pH of the solution. Quantitative retention of copper, zinc, and cadmium occurred at a wide range of pH values, while the retention for lead and iron was pH-dependent. The latter metals were adsorbed strongly only at pH 6 and 7, respectively. The breakthrough capacity was determined from the breakthrough curve, with values of 0.0035, 0.0008, 0.0011, 0.0028, and 0.0017 ng/mL for Cu, Zn, Cd, Pb, and Fe, respectively, being obtained. The analysis of a certified reference sample, sewage sludge of domestic origin (BCR No. 144), for cadmium and copper with a high accuracy ensures the feasibility of this technique for environmental analysis. Copyright 1994, American Chemical Society.
Sludge BCR 144 Spectrophotometry Immobilized cell Preconcentration pH Controlled pore glass Reference material

"Online Standard Addition Method With ICP-MS Using Flow Injection"
Anal. Chem. 1995 Volume 67, Issue 9 Pages 1553-1557
Diane Beauchemin

Abstract: A Perkin-Elmer SCIEX ELAN 500 instrument fitted with a mass flow controller, a PlasmaTherm torch and a translational stage for the torch box was used in conjunction with a single-line flow injection manifold in which a peristaltic pump controlled the flow of carrier to a sample injection valve connected to the Meinhard nebulizer by PTFE tubing. Operating conditions used to determine trace metals in 1% HNO3/0.01 M K medium and in standard seawater are tabulated. Initially, 1% HNO3 was used as carrier, into which a multi-element or single-element standard was injected. After rinsing of the loop, the sample was injected. The standard was then used as carrier for a further injection of sample. To minimize rinsing time, for the next run the sample was injected first into the standard carrier and then into the blank carrier, after which the standard was injected into the blank carrier. Sample consumption was reduced, a matrix-matched blank was not necessary, and sensitivity was close to that with continuous sample nebulization. However, precision was poorer than that of peak height calibration. The method was used to determine Mo in standard seawater. A single-line flow injection manifold was used to perform the standard addition method online with ICPMS. The proposed approach requires injection of the sample into two different carriers (i.e., a blank and a standard with a greater concentration than that of the sample), as well as injection of the standard in the blank carrier. The method takes into account the change in sensitivity induced by the sample upon its injection into the standard carrier. In the best conditions, one replicate multielemental analysis by the online standard addition method was accomplished in 200 s (using 100 mL injections). Furthermore, the setup induced only limited dispersion (i.e., the dispersion coefficient was between 1.2 and 2) and therefore provided sensitivity similar to that expected from direct continuous nebulization of the sample. Although precision was poorer than that which is typical of, for instance, external calibration, the proposed method adequately compensated for the effect of a 0.01 M K matrix, allowing the accurate determination of V, Co, Ni, Cu, Zn, Mo, Cd, Sb, and Pb in this matrix. The method was also successfully applied to the direct determination of Mo in seawater. Copyright 1995, American Chemical Society.
Sea Mass spectrometry Reference material Standard additions calibration

"Generation Of Cadmium Atoms At Room Temperature Using Vesicles And Its Application To Cadmium Determination By Cold Vapor Atomic Spectrometry"
Anal. Chem. 1995 Volume 67, Issue 13 Pages 2216-2223
A. Sanz-Medel, M. C. Valdes-Hevia y Temprano, N. Bordel Garcia, and M. R. Fernandez de la Campa

Abstract: In a batchwise system, Cd was reduced to the vapor by adding NaBH4 solution in 10 mM didodecyldimethylammonium bromide vesicles to the test solution in HCl (final concentration 0.4M) and 10 mM didodecyldimethylammonium bromide vesicles. The vapor was carried by Ar to a quartz cell for absorbance measurement at 228.8 nm or to an ICP torch for AES. Detection limits were 1 and 0.08 ng/ml by ICP-AES and AAS, respectively. An analogous continuous-flow system was also used, but gave poorer sensitivity. Generation efficiency was 75% at 0°C and 50% at room temperature. The nature of the measured species was investigated.
Spectrophotometry Spectrophotometry Volatile generation Optimization Volatile generation

"Voltammetric Determination Of High Concentrations Of Metal Ions In A Continuous-flow System At Vitreous-carbon Electrodes"
Fresenius J. Anal. Chem. 1985 Volume 322, Issue 3 Pages 334-335
B. Lendermann Contact Information und U. Giese

Abstract: The determination of 1 to 100 g L-1 of Pb or Cd in aqueous solution is effected with use of a microprocessor-controlled polarograph and a flow cell with a vitreous-carbon electrode vs. silver - AgCl. The mobile phase (0.8 mL min-1) was 0.1 M KNO3 and the scan rate was 600 mV s-1 starting at -0.45 and -0.60 V for Pb and Cd, respectively. The calibration graph for Pb was not rectilinear. The method may be applied to the analysis of electroplating solution and waste liquors.
Industrial Electrode Voltammetry

"Matrix Exchange Techniques For The Simultaneous Determination Of Several Elements In Flow Injection Potentiometric Stripping Analysis"
Fresenius J. Anal. Chem. 1985 Volume 322, Issue 3 Pages 255-260
G. Schulze, W. B&ouml;nigk and W. Frenzel

Abstract: The determination of Pb, Sn, Cd and Tl in their binary, ternary and quaternary mixtures in the 1 to 10 mg L-1 range is described, with use of a Tecator Striptec measuring system with a flow injection analysis-Star unit and electrochemical detection at -1 V with a vitreous-carbon electrode; the mobile phase (1.6 mL min-1) was 0.01 M HCl containing 40 mg L-1 of Hg(II). Samples containing 50 mg L-1 of Hg(II) were injected, with deposition times of 20 to 60 s and a stripping time of 12.4 s. The optimum electrolyte was aqueous 5 M NH3 - 0.5 M KOH. The calibration graphs were rectilinear for the cited range.
Electrode Potentiometric stripping analysis Simultaneous analysis Tecator

"Digestion-free Determination Of Trace Metals In Beverages By Inverse Voltammetry In Flow-through Cells"
Fresenius J. Anal. Chem. 1987 Volume 327, Issue 2 Pages 175-178
Faramarz Wahdat und Rolf Neeb

Abstract: Digestion-free determination of trace-metals (Zn, Cd, Pb, Cu) in beverages by inverse voltammetry in a flow-through cell equipped with a mercury film-electrode is described. Optimal enrichment potentials are obtained by inspection of the pseudopolarograms of the elements in the original diluted sample solution. After the deposition step in the untreated sample solution stripping is effected in a proper supporting electrolyte after medium exchange. Values obtained by this techniques with various samples compare well with those obtained by usual procedures including wet digestion of the samples.
Wine Voltammetry Flowcell

"Preparation And Performance Of A Coated Tubular Solid-state Cadmium-selective Electrode In Flow Injection Analysis"
Fresenius J. Anal. Chem. 1988 Volume 331, Issue 6 Pages 594-598
Jacobus F. van Staden

Abstract: The cited electrode contained a Cd tube (8 mm x 1 mm) joined by its ends to Tygon tubes (2 cm x 0.5 mm) and wrapped around with the inner wire of a shielded cable to ensure electrical contact with an Orion Research (model 901) microprocessor Ionalyzer, and the unit was isolated with epoxy-resin. After cleaning the Cd tube internally with concentrated HNO3 and water, a Cd - CdS membrane was formed and activated by electro-deposition of CdS on to its inner wall from 0.1 M Na2S at 2 mL min-1 and 20 mA cm-2. The electrode was conditioned in 1 mM Cd(NO3)2 at pH 3 for 24 h. When used with an Orion 90-02 double-junction reference electrode with aqueous 10% KNO3 in the outer chamber in a described flow injection analysis system to analyze 30 µL samples at a rate of 60 h-1, the electrode showed rectilinear response from 0.25 to 10 g L-1 of Cd(II). There was no interference from Fe(II) or from up to 5 g L-1 of Cl- or SO42- or 1 g L-1 of NO3-; Ag, Hg(II), Cu(II) and Fe(III) interfered at 1 mg l-1, and I-, S2-, Pb(II) and Br- interfered at 5, 10, >100 and >100 mg l-1, respectively.
Electrode Electrode Potentiometry Apparatus Interferences

"Computerized Flow Injection Potentiometric Stripping Analysis With Large-volume Wall-jet Cell"
Fresenius J. Anal. Chem. 1988 Volume 332, Issue 2 Pages 148-152
Wojciech Matuszewski, Marek Trojanowicz and Wolfgang Frenzel

Abstract: A flow injection system is described incorporating a large-volume wall-jet cell (diagram given) and a microcomputer for digital signal recording and data processing. The working electrode was a vitreous-carbon rod of 3 mm diameter pressed into PTFE. A SCE was used as reference electrode and platinum foil (1 cm2) was used as auxiliary electrode. The electrodes were immersed in 0.1 M HCl (carrier solution). The system was applied in the simultaneous determination of Cd and Pb in geological materials. Rock or ore (100 mg) was mixed with 5 mL of 40% HF and heated to dryness in a sand bath at 400°C. The residue was dissolved in 5 mL of 4% H3BO3 and the solution was diluted to 10 mL (rocks) or 50 mL (ore) with 0.1 M HCl. A 750 µL portion of solution was injected; the deposition time was 8 min at -1.15 V vs a SCE; the flow rate was 1.5 mL min-1. Potentiometric stripping was carried out under stopped-flow conditions by using 40 ppm of Hg(II) in 0.1 M HCl as oxidizing agent. Results agreed with those by AAS.
Geological Geological Geological Potentiometric stripping analysis Electrode Electrode Computer Method comparison Stopped-flow

"Ion-chromatographic Trace Analysis Of Mercury, Cadmium And Zinc By Post-column Derivatization With A Water-soluble Porphyrin"
Fresenius J. Anal. Chem. 1989 Volume 334, Issue 6 Pages 507-510
Daren Yan, Jingan Zhang and Georg Schwedt

Abstract: Sample solution was subjected to ion chromatography on a Nucleosil SA (10 µm) column (20 cm x 4 mm) with 0.5% NaCl solution in 1 mM tartrate (pH 4.3) as mobile phase (0.6 mL min-1). Post-column reaction with 10 µM-4,4',4'',4'''-(21H,23H-porphine-5,10,15,20-tetrayl)tetrabenzenesulfonic acid - 1 µM-4-(2-pyridylazo)resorcinol - 0.6% of NaCl - 32 mM borate buffer of pH 11.5 (0.3 mL min-1) was carried out in a T-shaped mixing cell, and detection was at 430 nm. Calibration graphs (injection volume 0.1 ml) were rectilinear for 0.002 to 0.8, 0.1 to 8 and 0.05 to 20 mg L-1 for Cd, Hg and Zn, respectively; corresponding detection limits were 0.5, 50 and 10 µg l-1. The method was successfully applied in the determination of these metals in waste water, a silicate sample and rice.
Waste Rice HPIC Spectrophotometry Post-column derivatization Buffer Mixing chamber

"New Possibility For The Calibration Of Potentiometric Determinations Under Flow Injection Conditions. 2. Analytical Applications"
Fresenius J. Anal. Chem. 1989 Volume 335, Issue 2 Pages 210-215
H. M&uuml;ller und J. Kramer

Abstract: An equation has been developed in which the Nernst equation has been expanded to include the effect of dispersion in FIA - ion-selective potentiometry, using the Gaussian gamma function. With use of this equation, determinations may be made without explicit knowledge of parameters such as flow rate, reactor tube length and electrode slope factor. The apparatus has two identical channels in which solid-state detector electrodes are mounted. Identical 'base' solution are pumped through the two channels and sample and standard solution are then injected. The method was applied in the determination of I- (0.2 to 2 mM), with a carrier solution containing 0.1 mM I- and 0.1 M KNO3 and with Ag2S - AgI electrodes. Coefficients of variation were 0.5 to 0.75% and there was no significant difference between the results obtained and those obtained by the conventional procedure (using the Nernst slope). Determinations of Cd (0.1 to 0.5 mM) were also carried out.
Potentiometry Electrode Dispersion Gaussian function Method comparison

"Microanalytical Determination Of Metallic Constituents Of River Sediments"
Fresenius J. Anal. Chem. 1991 Volume 340, Issue 4 Pages 223-229
E. Ruiz, A. Echeand&iacute;a and F. Romero

Abstract: The distribution of metallic constituents in torrential rivers as a function of the size particle cannot be frequently achieved by conventional analytical procedures, because of the lack of sufficient amounts of the fine fractions. For the study of river sediments in the Basque Country, microanalytical methods have been developed both for major (Na, K, Ca, Mg, Fe, Al, Si) and trace (Cu, Zn, Mn, Cr, Pb, Ni, Cd) components. Wet digestion in PTFE vessels at 140°C was done with 0.05 g sample using HNO-3-HClO-4-HF-H-3BO-3 or HNO-3-HClO-4, respectively. Further determinations were made by i) emission spectrometry (Na, K), ii) visible spectrophotometry (A1), iii) FIA (Fe, Si) and iv) AAS with flow spoiler (Ca, Mg, Cu, Zn, Mn) or graphite furnace (Cr, Pb, Ni, Cd). The proposed method has been checked with a standard sample obtaining mean values almost coincident with the certified ones and variation coefficients lower than 2% for major and 8% for trace components. Then it was applied to total samples and the fine fractions (<63 µm) of 26 samples of sediments from three torrential rivers. Replicated values with analogous variation coefficients were obtained. Some considerations on distribution of major and trace constituents as a function of particle size are also included.
River Spectrophotometry Spectrophotometry Spectrophotometry Spectrophotometry Sample preparation Reference material

"Determination Of Ultratrace Concentrations Of Elements By Means Of Online Solid Sorbent Extraction Graphite Furnace Atomic Absorption Spectrometry"
Fresenius J. Anal. Chem. 1992 Volume 343, Issue 9-10 Pages 754-755
Michael Sperling, Xuefeng Yin and Bernhard Welz

Abstract: Solid sorbent extraction using a microcolumn in an automated system was successfully coupled with a graphite furnace for atomic absorption spectrometry. Bonded silica with octadecyl functional groups (C-18 reversed phase material) was used in a 15 µL conically shaped microcolumn as a sorbent for the metal complexes formed online with Na diethyldithiocarbamate. Column elution was performed with an EtOH eluent into a PTFE capillary used for eluate storage and transfer into the graphite tube. With a sample loading time of 60 s and direct introduction of the eluate portion containing the highest analyte concentration. into the graphite tube, an enrichment factor of ~20 was realized. Effective elimination of contamination by the closed system and online purifn. of the complexing agent together with highly selective separation of trace metals from alkaline and earth alkaline elements allowed the determination of ultratrace metals in seawater and deionized water. Using only 3 mL of sample, detection limits for Cd, Co, Cu, Pb, and Ni of 0.8, 12, 17, 6.5, and 36 ng/L, respectively, was achieved.
Sea Water Spectrophotometry Sample preparation C18 Preconcentration Ultratrace Solid phase extraction

"Flame Atomic Absorption Spectrometric Determination Of Cadmium And Copper In Biological Reference Materials Using Online Sorbent Extraction Preconcentration"
Fresenius J. Anal. Chem. 1992 Volume 344, Issue 12 Pages 535-540
Shukun Xu, Michael Sperling and Bernhard Welz

Abstract: Animal or plant tissue reference material (0.5 g) was subjected to acid digestion and the residue was diluted with HNO3. Urine samples for analysis were diluted with water before addition of HNO3. The solution was loaded into a flow injection manifold where it was merged with a stream of 0.05% diethylammonium-NN-diethyldithiocarbamate. The complex formed was extracted online on a conical 100 µL micro-column of RP-C 18 sorbent and the chelates were eluted with methanol directly into the nebulizer - burner system of the spectrometer. Small air segments introduced before and after elution prevented the eluent from mixing with the sample solution and increased sensitivity. A sampling frequency of 85 h-1 was achieved, with a sample loading time of 30 s at a flow rate of 4.0 mL min-1. The enrichment factor for Cd and Cu was 20 and the detection limits were 0.15 and 0.2 µg L-1 for Cd and Cu, respectively. The coefficient of variation were 2.3% for 10 µL L-1 of Cd and 1.4% for 45 µg L-1 of Cu (n = 11). The procedure was suitable for the determination of Cu in biological materials and for Cd in urine. Low recoveries were obtained for Cd in samples containing high levels of Cu and/or Fe. Cadmium and copper at the µg/g to ng/g level in plant and animal tissue reference materials, and at the µg/L level in urine were determined by flame atomic absorption spectrometry using online sorbent extraction pre-concentration based on flow injection techniques. Bonded silica reversed phase sorbent with octadecyl functional groups (RP-C 18), packed in a 100 µL column, was used to collect the diethylammonium-N,N-diethyldithiocarbamate (DDTC) complex formed online in the sample digests at low pH. Methanol was used to elute the analyte chelates directly into the nebulizer-burner system of the spectrometer. Small air segments introduced before and after elution prevented the eluent from mixing with the sample solution and increased the sensitivity. A sampling frequency of 85/h could be obtained with a sample loading time of 30 s at a flow rate of 4.0 mL/min. The enrichment factor for both elements was 20 and the enhancement factors, including the effect of the organic solvent and with the flow spoiler removed, were 126 and 114 for cadmium and copper, respectively. The detection limits (3s) were 0.15 µg/L for cadmium and 0.2 µg/L for copper. The precision was 2.3% and 1.4% RSD for 10 µg/L Cd and 45 µg/L Cu, respectively. (n = 11). Results for the determination of cadmium and copper in various biological reference materials were typically in good agreement with certified values. Low recoveries were observed, however, for cadmium in samples containing high levels of copper and/or iron, such as bovine liver.
NIST 1577 Liver Plant Urine Sample preparation Spectrophotometry Sample preparation Reference material Air segmentation Preconcentration C18 Solid phase extraction

"Analysis Of Standard Reference Materials After Microwave-oven Digestion In Open Vessels Using Graphite Furnace Atomic Absorption Spectrophotometry And Zeeman-effect Background Correction"
Fresenius J. Anal. Chem. 1993 Volume 347, Issue 6-7 Pages 233-237
D. Chakraborti, M. Burguera and J. L. Burguera

Abstract: Heating-covered teflon digestion vials located inside a reheatable container in the presence of different acid mixtures with microwave oven dissolve the metals from biological and environmental certified reference materials. Pb, Cd, Cu, Mn and Fe from the dissolved samples are determined by graphite furnace atomic absorption spectrophotometry and Zeeman-effect background correction. The method allows the treatment of about 100 samples per operation. [References: 10]
Biological Environmental Sample preparation Spectrophotometry Reference material

"Digestion-free Determination Of Heavy Metals In Honey Using Anodic-stripping Differential Pulse Voltammetry And Potentiometric-stripping Analysis"
Fresenius J. Anal. Chem. 1995 Volume 351, Issue 7 Pages 678-682
Yingjian Li, Faramarz Wahdat and Rolf Neeb

Abstract: Experiments have been carried out to assess the potential of differential pulse voltammetry and potential stripping analysis for determining Pb, Cu and Cd directly in dissolved honey samples using a flow-through cell. With the hanging mercury drop electrode Pb alone can be determined only if the electrode is first modified in-situ with Triton X 100 to increase the separation between the Pb peak and a broad, interfering adsorption peak which overlaps the Cu peak. If the (more sensitive) thin film mercury electrode is used the interference encountered is less so also Cu and Cd can be determined. With potentiometric stripping analysis Cu and Pb can be determined using normal procedures. The determination of Cd, however, can only be carried out if the concentration of the oxidizing agent [Hg(II)] in solution is decreased. A good agreement has been obtained between the values found and those obtained after high pressure digestion of the samples.
Food Potentiometric stripping analysis Voltammetry Voltammetry

"Separation And Determination Of Cadmium In Biological Materials By Continuous-flow Fluid Extraction Coupled To Flow Injection ICP-AES"
Fresenius J. Anal. Chem. 1995 Volume 351, Issue 8 Pages 802-804
E. Vereda Alonso, M. T. Siles Cordero, A. Garc&iacute;a de Torres and J. M. Cano Pav&oacute;n

Abstract: Biological reference materials was dried, powdered and mineralized by heating under reflux with 65% nitric acid. H2O2 was added, the mixture was concentrated to remove the nitric acid and NaClO4 was added to give an ionic strength of 0.1 and the pH was adjusted to 3.6. The aqueous sample stream (0.68 ml/min) was merged with a carrier stream (0.22 ml/min) of 1,5-bis(di-2-pyridyl)methylene thiocarbohydrazide in IBMK at a solvent segmentor. The stream passed through an extraction coil (100 cm x 0.35 mm i.d.) to a membrane phase separator. The organic phase filled an injection loop and was carried to the ICP-AES instrument by a carrier stream (1.2 ml/min) of IBMK/DMF and the solution was analyzed. The operating conditions were plasma flow rate of 12 l/min, r.f. generator frequency of 40 MHz and a wavelength of 228.802 nm. The calibration graph was linear for 10^-2000 ng/ml with a detection limit of 8.7 ng/ml and RSD (n = 7) of 3.4% for 100 ng/ml of Cd.
Biological Sample preparation Spectrophotometry Sample preparation Reference material MIBK Solvent extraction Phase separator Organic phase detection

"Determination Of Cadmium And Bismuth In High-purity Zinc Metal By Inductively Coupled Plasma Mass Spectrometry With Online Matrix Separation"
Fresenius J. Anal. Chem. 1995 Volume 353, Issue 2 Pages 162-166
Yasumasa Sayama, Yutaka Hayashibe and Masamitsu Fukuda

Abstract: High-purity Zn metal was dissolved in 7 M HNO3 and evaporated to near dryness. The residue was dissolved in 0.5 M HNO3 and injected into a carrier stream 1 ml/min) of 0.1 M KI. The resulting solution passed through an anion-exchange mini-column (10 cm x 1 mm i.d.) which adsorbed Cd and Bi as the iodide complex. After 3.3 min, the column was washed with 0.1 M HNO3 for 20 min at 0.4 ml/min, the ICP-MS instrument was cleaned with 0.4 M HNO3 (0.4 ml/min), Cd and Bi were eluted from the column with 2 M HNO3 and the eluate was introduced directly into the ICP-MS instrument. The ICP-MS instrumental parameters are tabulated. Calibration graphs were obtained for up to 10 ng/ml of Bi and Cd with detection limits of 0.075 and 0.81 ng/g, respectively, for single injections and 0.014 and 0.16 ng/g. respectively, for multiple injections. Recoveries were 109% Cd and 92% Bi at 10 ng levels.
High purity Mass spectrometry Sample preparation Resin Preconcentration Complexation

"Ion Exchange Micro Columns For Online Preconcentration Of Heavy Metals. 2. Online Break-through Test For Zinc, Cadmium And Lead"
Fresenius J. Anal. Chem. 1995 Volume 353, Issue 2 Pages 119-122
O. Elsholz, and G. Schulze

Abstract: An on-line break-through test for zinc, cadmium and lead has been carried out by means of a flow-through cell and computerized potentiometric stripping analysis. This test has been applied to seventeen ion-exchange materials and enabled within a short time a predecision about the suitability of a resin for a special precon-centration problem. For the determination of the three trace elements in drinking water five ion exchangers are found to be appropriate without restriction and eight resins with some restrictions (not suitable for all three elements, weak matrix influences).
Ion exchange Column Preconcentration

"Automatic Flow Injection System For The Determination Of Heavy Metals In Sewage Sludge By Microwave Digestion And Detection By Inductively Coupled Plasma Atomic-emission Spectrometry."
Fresenius J. Anal. Chem. 1996 Volume 355, Issue 2 Pages 112-119
Luis Bordera, Vicente Hernandis and A. Canals

Abstract: An automated dual-channel flow injection manifold was used to determine heavy metal concentrations of 77.7-4059 µg/g in sewage sludge. A suspension of sewage sludge containing 0.5-0.75% of solids in 1.5 M HNO3 was loaded into a digestion coil (3 m x 0.8 mm i.d.) and subjected to microwave radiation at 662 W for 360 s. The digest (~e;6 ml) was inserted into a 1.5 M HNO3 carrier stream (1 ml/min) and propelled to the sequential ICP-AES spectrometer where signals for Zn (213.856 nm), Cu (324.756 nm), Pb (220.353 nm), Cr (283.563 nm), Cd (228.802 nm) and Ni (231.604 nm) were recorded. The method was validated by analyzing a certified reference material (BCR No. 146) and relative errors of -4.8 to +2% were obtained for all elements apart from Ni (-10.4%). The complete analysis took ~e;12 min.
Sludge BCR 146 Sample preparation Spectrophotometry Reference material Microwave Online digestion Slurry

"Determination Of 0.1 To 1000 .mu.g/ml Cadmium In A Hydrometallurgical Zinc Refining Process Stream By A Flow Injection Technique With Computer-controlled Injection Method"
Fresenius J. Anal. Chem. 1996 Volume 355, Issue 2 Pages 144-149
Yutaka Hayashibe, Yasumasa Sayama and Koichi Oguma

Abstract: The computer-controlled flow injection system for the determination of Cd involved the online separation of Cd from the Zn matrix by anion exchange and spectrophotometric detection with 1-(4-nitrophenyl)-3-(4-phenylazophenyl)triazine (Cadion) as chromogenic reagent. A sample of 0.56-350 µL was inserted into a 0.1 M KI carrier stream (1 ml/min) and passed through a Bio-Rad AG1-X8 column (100-200 mesh; 10 cm x 1 mm i.d.). The retained analyte was eluted with a 1 M HNO3 stream (1 ml/min) which was merged with a chromogenic reagent stream formed by mixing 0.006% Cadion/0.1 M KOH/0.1% Triton X-100 (1.5 ml/min) with 17 mM sodium citrate/8.8 mM potassium sodium tartrate/2 M KOH (1.5 ml/min). The flow was propelled to the spectrophotometric detector were the absorbance at 480 nm was recorded. Calibration graphs for Cd were linear for 20-1000 µg/ml (0.56 µm injected) and 0.05-2 µg/ml (350 µL injected). RSD were 6.2% (n = 100) for 0.56 µL of 850 µg/ml Cd and 5% (n = 5) for 350 µL of 0.14 µg/ml Cd. The sampling frequency was 5 samples/h.
Spectrophotometry Chromogenic reagent Computer Triton X Surfactant

"Simultaneous Determination Of Metal-ion Concentrations In Binary-mixtures With A Multi-LED Photometer"
Fresenius J. Anal. Chem. 1997 Volume 357, Issue 8 Pages 1056-1060
P. C. Hauser and Thusitha W. T. Rupasinghe

Abstract: A compact photometer is based on up to seven different light-emitting diodes whose light is guided into a photometric cell by means of a fiber-optic coupler. The wavelength is selected by switching on the appropriate light source. The application of this multiwavelength photometer to the determination of binary metal ion samples is demonstrated using model mixtures. Solutions of Fe, Co, Cu, Ni, Cr and Mn were used in combination with several photometric reagents. It was found that the instrument yielded concentration measurements which were usually within a few percent of the correct concentration. These results are comparable to reported data obtained with conventional instruments for similar measurements. The application of the instrument for simultaneous determination in flow injection analysis employing rapid computer controlled switching of the light-emitting diodes is also demonstrated. A limitation in the use of light-emitting diodes for the simultaneous determination was found to arise from the fact that in some instances non-linear calibration curves are obtained when employing light-emitting diodes as light sources. This occurs when the absorptivity of the measured compound changes over the emission band of the diodes. Multiple regression analysis is then not easily possible. A compact photometer is used based on up to seven different LED (from blue to near-IR); the light is guided into a photometric cell via a fiber-optic coupler. Wavelength is selected by switching on the appropriate light source. The photometer was applied to the analysis of several model metal ion mixtures in combination with several photometric reagents (details given). Results obtained were comparable to those reported using conventional instruments. This instrument was also applied to simultaneous determination in flow injection analysis using rapid computer-controlled switching of the LED. 19 References
Spectrophotometry Chemometrics Light emitting diode Multicomponent Optical fiber Computer

"Flow Injection Potentiometric Stripping Analysis And Potentiometric Stripping Coulometry. Micro-analytical Methods For Heavy Metals"
Microchim. Acta 1984 Volume 82, Issue 3-4 Pages 191-201
G. Schulze, M. Husch and W. Frenzel

Abstract: The analysis, with a wall-jet (Metrohm EA-1096) or porous-carbon (prep. described) working electrode, has been successfully applied to the determination of Zn, Cd and Pb, rectilinear responses being obtained in the range 100 ng to 2.5 µg. A vitreous-carbon counter-electrode and a silver - AgCl reference electrode are used. With a 250 µL sample and a flow rate of 0.5 mL min-1, the limit of detection is 50 µg l-1. A new concept of potentiometric stripping coulometry depends on the use of Faraday's law to calculate the mass of deposited metal from the stripping time. When applied to the determination of 130 ng of Pb, a value of 133 ng was obtained.
Coulometry Potentiometric stripping analysis Electrode Electrode

"Trace Metal Ion Preconcentration For Flame Atomic Absorption By An Immobilized NNN'-tris-(2-pyridylmethyl)ethylenediamine (TriPEN) Chelate Ion Exchanger In A Flow Injection System"
Microchim. Acta 1985 Volume 87, Issue 3-4 Pages 209-221
M. Bengtsson, F. Malamas, A. Torstensson, O. Regnell and G. Johansson

Abstract: The synthesis of the chelating ion exchanger, which involves use of N-[3-(trimethoxysilyl)propyl]ethylenediamine, is described. A 100 µL portion of the product in a PTFE tube (1.9 mm i.d.) was mounted in the flow injection system before the flame; a diagram of the manifold is presented. Trace metal retained on the ion exchanger was eluted as a sharp peak with a 670 µL injection of strong acid. Injection of 0.83 mL of a 0.2 ppm Cd solution during 10 s and of 83.3 mL of a 2-ppb Cd solution during 1000 s (elution with 1 M HNO3) gave sensitivity enhanced by factors of 4.6 and 463, respectively, with respect to the steady-state response to a 1 ppm Cd solution
Ion exchange Spectrophotometry Preconcentration Chelation

"Determination Of Ultratrace Amounts Of Copper And Cadmium In Seawater By Graphite Furnace Atomic Absorption Spectrometry With Flow Injection Semi Online Preconcentration"
Microchem. J. 1993 Volume 48, Issue 3 Pages 326-342
Wang M. H., Yuzefovsky A. I. and Michel R. G.

Abstract: Methods are described for the determination of ultratrace amounts of copper and cadmium in seawater by graphite furnace atomic absorption spectrometry with flow-injection, microcolumn pre-concentration. A new type of C18 column loaded with sodium diethyldithiocarbamate (sodium-DDC) was used to extract copper and cadmium from seawater as the DDC chelates. The analytical effects of the pH of the mixture of the sample and sodium-DDC solutions and the concentration of the chelating reagent were studied. Sodium-DDC-loaded columns and unloaded C18 columns with different shapes and volumes were compared. To determine copper in seawater, a simple aqueous calibration was made with a mixture of palladium and magnesium nitrate as a matrix modifier, while for cadmium no matrix modifier was necessary. This method required only small seawater volumes, 600 and 400 µl for the determination of copper and cadmium respectively, with pre-concentration factors of 15-fold for copper and 10-fold for cadmium. Detection limits for the pre-concentration of aqueous solutions of copper and cadmium were 0.024 and 0.004 µg liter-;1 (3s), respectively. Results for determinations of copper and cadmium in National Research Council of Canada, CASS-2, Nearshore Seawater Reference Material showed no significant differences between the certified values and the measured values, based on Student's t test at the 95% confidence level. The relative standard deviations of the various measurements varied between 2 and 8%.
Sea Spectrophotometry Preconcentration Ultratrace

"Determination Of Metal Ions By Flow Injection Analysis With Peroxyoxalate Chemiluminescence Detection"
Microchem. J. 1996 Volume 53, Issue 1 Pages 93-98
Kenji Sato and Shigeyuki Tanaka

Abstract: A bis(2,4,6-trichlorophenyl) oxalate (TCPO) chemiluminescence method for the determination of metal ions, Al(III), Zn(II), Cd(II) and In(III), based on the conversion of metal ion to fluorescent metal chelate by oxine (quinolin-8-ol) using a FIA technique was investigated. Portions (1 ml) of metal standard solutions were mixed with 100 µL 0.5 M acetate buffer of pH 7 and 1.5 mL 20 mM quinolin-8-ol in 1,4-dioxane (solvent A). Portions (20 µL) of the resultant solution were injected into a stream of aqueous 40% solvent A (1 mL/min) in a flow injection system (schematic shown) and mixed with a reagent stream containing 0.5 mM TCPO and 5 mM H2O2 in ethyl acetate/acetonitrile (1:9) at 1.5 ml/min. The chemiluminescence (CL) intensity was measured on a Shimadzu CLD-10A detector (shimadzu, Kyoto, Japan). Calibration graphs were linear from 0.05-5 ppm for each metal ion and the detection limits were 20, 30 and 70 ppb, respectively, for Al(III) and Cd(II), Zn(II) and In(III). RSD (n = 10) were ~2%. Results compared well with those obtained by an HPLC method with chemiluminescence detection using identical reagents in which the detection limits were 0.2, 0.6, 3 and 3 ng, respectively, for Al(III), Zn(II), Cd(II) and In(III).
Chemiluminescence 8-Hydroxyquinoline

"Determination Of Cadmium, Cobalt, Copper, Manganese, Nickel, Lead And Zinc By Inductively Coupled Plasma Mass Spectroscopy Or Flame Atomic Absorption Spectrometry After Online Preconcentration And Solvent Extraction By Flow Injection System"
Microchem. J. 1996 Volume 54, Issue 4 Pages 402-411
A. Bortoli a, M. Gerottoa, M. Marchioria, F. Maricontib, M. Palontaa and A. Troncona

Abstract: A flow injection manifold and sequence of operations for online separation and pre-concentration of Cd, Co, Cu, Mn, Ni, Pb and Zn are diagramatically presented. Bonded silica with octadecyl functional group C18, packed in a microcolumn of 100 µL capacity, was used to collect diethyldithiocarbamate complexes of the heavy metals in aqueous solution. The metals were complexed with a chelating agent, adsorbed on the C18 column and eluted with methanol directly in the flow injection system. The metals were then determined by GF AAS or ICP-MS (details given). Calibration graphs and detection limits are presented.
Environmental Environmental Spectrophotometry Mass spectrometry Sample preparation Spectrophotometry Preconcentration Solvent extraction C18 Chelation

"Online Multielement Preconcentration And Inductively Coupled Plasma Atomic Emission Spectrometric Determination Of Transition Metals Using A Flow Injection Hydraulic High-pressure Nebulization-desolvation Sample Introduction System"
Microchem. J. 1998 Volume 58, Issue 3 Pages 245-250
Attila G&aacute;sp&aacute;r, J&oacute;zsef Posta, Mih&aacute;ly Braun and Csilla S&oacute;gor

Abstract: A method was developed for simultaneous pre-concentration and online determination of 15 transition metals (Ag, Au, Cd, Cr, Cu, Fe, In, Ni, Pb, Pd, Pt, Ti, Tl, V, Zn). A polyether-ether-ketone (PEEK) loop as pre-concentration unit introduced by the authors earlier was used for the multielement flow injection (FI) pre-concentration of transition metal-pyrrolidinedithiocarbamate complexes. The pre-concentrated complexes were eluted with iso-Bu Me ketone and introduced into the inductively coupled plasma with a hydraulic high-pressure nebulizer (HHPN) and desolvation unit. The desolvation system, the use of which was necessary for aerosol of iso-Bu Me ketone eluant, was optimized. The enrichment factors of the 15 transition metals were 14-67 due to 2 min of pre-concentration time.
Spectrophotometry Preconcentration Polyetheretherketone Complexation MIBK Optimization Interface

"Soluble And Particulate Metals In The Adige River"
Microchem. J. 1998 Volume 59, Issue 1 Pages 19-31
A. Bortoli, E. Dell'Andrea, M. Gerotto, M. Marchiori, M. Palonta and A. Troncon

Abstract: The concentrations of 10 metals (As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) were monitored over a one-year period in the waters of the lower Adige River, Italy. Concentrations in the dissolved and particulate phases were measured, thus constructing a database on metal variability. The concentrations. of Cd, Cr, Cu, Mn, Ni, and Pb in these water samples are too low to be directly determined by flame atomic absorption spectrometry or graphite furnace atomic absorption spectrometry. In this work, Cd, Co, Cu, Mn, Ni, Pb, and Zn were determined by inductively coupled plasma mass spectrometry (ICP-MS) or GFAAS after online pre-concentration. and following solvent elution with a flow injection analysis system (FIAS). The eluted samples were also dried in a vacuum container and restored to a small volume with concentrated HNO3 and Milli-Q water for anal. by ICP-MS or GFAAS. The concentrations of soluble Cd, Fe, and Mn and particulate As, Cr, Cu, Pb, and Zn are well correlated with seasonal variability (P < 0.01). Dissolved As and Fe are well correlated (P < 0.01), and with respect to the particulate phase, good correlations are observed between Pb, Cd, and Cu.
River Mass spectrometry Spectrophotometry Sample preparation Preconcentration Solvent extraction

"Determination Of Trace Elements In Power Plant Emissions By Inductively Coupled Plasma Mass Spectrometry: Comparison With Other Spectrometric Techniques"
Microchem. J. 1998 Volume 59, Issue 2 Pages 203-218
M. Bettinelli, S. Spezia, U. Baroni and G. Bizzarri

Abstract: Particulate matter in stack effluents of coal-fired plants was collected with an isokinetic probe nozzle suitable for (a) total particulate samplings on membrane filters and (b) sampling with a low volume 10-stage single orifice cascade impactor plus a backup filter. A microwave digestion method using an acid mixture of HNO3-HCl-HF in a closed vessel was developed for the determination of major, minor, and trace elements in very small amounts of sample. Analyses were carried out by inductively coupled plasma mass spectrometry (ICP-MS). A recovery study was conducted using multielemental standard solutions, NIST1633a Trace Elements in Coal Fly Ash and NIST 1648 Urban Particulate Matter, to examine the capabilities of the method. The results for real samples dissolved by this procedure were compared with results obtained by instrumental neutron activation anal., graphite furnace atomic absorption spectrometry, and flow injection hydride generation atomic absorption spectrometry. The anal. capabilities of ICP-MS make it one of the techniques of choice for the determination of trace elements in emission particulate matter collected in different granulometric particle sizes.
Industrial NIST 1633 NIST 1648 Mass spectrometry Sample preparation Method comparison Reference material

"Flow Injection Online Preconcentration And Flame AAS Determination Of Copper, Cadmium And Lead In Marine Sediment Samples"
Anal. Lett. 1997 Volume 30, Issue 5 Pages 1037-1050
S. Kartikeyan; B. Vijayalekshmy; S. Chandramouleeswaran; T. P. Rao; C. S. P. Iyer

Abstract: Marine sediment (0.25 g) was mixed with 5 mL of 48% HF, 30 mL of 70% HNO3 and 2-5 drops of 98% H2SO4 and the mixture was digested (details given). Sample and ammoniacal dithizonate solutions were pumped simultaneously and mixed online. Preconcentration was performed on a C18 column over 1 min and Cu, Cd and Pb were eluted with acidified methanol and injected directly into the nebulizer for atomization in an air-acetylene flame. The calibration graph was linear from 1-40, 0.6-8 and 3-40 ppb, with detection limits of 1.2, 0.6 and 3 ppb Cu, Cd, and Pb, respectively. RSD were
Marine Sample preparation Spectrophotometry C18 Preconcentration

"Removal Of Oxygen In Flowing Solutions Using A Photochemical Process"
Electroanalysis 1992 Volume 4, Issue 3 Pages 323-326
Joseph N. Barisci, Gordon G. Wallace

Abstract: The online deoxygenation of solution in flow systems by the photochemical reaction of O with an organic acid, e.g., formic, citric, oxalic, tartaric or acetic acid, in the flowing solution is described. Citric acid was the best O scavenger and proved more efficient than conventional purging with N gas. The method was applied in the detection of Cu, Cd and Pb, by flow injection anodic-stripping voltammetry.
Voltammetry Interferences Photochemistry

"Individual And Simultaneous Determination Of Zinc And Cadmium In Biological Tissues By Flow Injection Stripping Voltammetric Analysis"
Electroanalysis 1994 Volume 6, Issue 9 Pages 764-768
A. Izquierdo, M. D. Luque De Castro, M. Valc&aacute;rcel

Abstract: Lyophilized samples were digested as described by Bond et al. (cf. Anal. Chem., 1982, 54, 2318) and analyzed by the cited technique. Detection was performed using a polarograph connected to a wall jet cell with a vitreous working electrode, Ag/AgCl (3 M KCl) reference electrode and Au auxiliary electrode. Before analysis, the working electrode surface was conditioned with a stream of 0.1 µM-Hg(II) (0.2 ml/min) for the deposition of a Hg film at a working electrode potential of -1.0 V vs. Ag/AgCl for 20 min, followed by 0.0 V for 2 min. The stream was then switched to a carrier of 1 M acetate buffer solution (0.2 ml/min) of pH 4.5 into which the sample (600 µL) was injected and a deposition potential of -1.0 V was applied to the working electrode. Three minutes after injection, the flow was halted, and 5 s later a positive differential pulse scan from -1.0-0.0 V (repetition time 0.4 s; pulse amplitude 50 mV; scan rate 40 mV/s) was applied. Detection limits were 0.8 nM and 2 nM for Cd and Zn, respectively, corresponding determination limits were 1 nM and 5 nM. RSD were 1.57% (Cd) and 5.6% (Zn). Results for reference materials agreed with certified values. No interference caused by the formation of intermetallic compounds was detected.
Biological tissue Voltammetry Electrode Electrode Interferences Reference material

"Simultaneous Determination Of Copper, Lead, Cadmium, And Zinc In Previously Lyophilized Biological Tissues Using Flow Injection Analysis/anodic Stripping Voltammetry"
Electroanalysis 1994 Volume 6, Issue 10 Pages 894-902
A Izquierdo, M. D. Luque de Castro, M. Valc&aacute;rcel

Abstract: Improvements in three main aspects of the analysis of metal traces in biological tissues are proposed, namely: (a) lyophilization of the samples both to preserve them and to favor the digestion process; (b) digestion of the lyophilized tissues using an effective and fast procedure; and (c) automatic determination of the target analytes by flow-injection analysis/anodic stripping voltammetry (FIA/ASV). After optimization of these steps, the overall procedure was successfully applied to the simultaneous determination of copper, lead, cadmium, and zinc in certified reference materials (CRMs) and fresh bovine liver samples with good results. Finally, the performance of the method was validated by a statistical study using parameters of the certification campaign of the CRMs; the results obtained being within, or close to, the confidence levels of the certification campaign.
Liver Voltammetry Simultaneous analysis

"Separation Of The Depolarizer From Surface-active Substances In The Tubes Of A Flow Injection System"
Electroanalysis 1997 Volume 9, Issue 10 Pages 781-787
Wladyslaw W. Kubiak*, Miroslaw M. Strozik

Abstract: The possibility to separate depolarizer and surfactant bands directly in a flow injection system is reported. Transport of a surfactant is according to an adsorptive or a hydrodynamic mechanism. In the former case a surfactant is transported slower than a depolarizer whereas in the latter case it is transported faster than a depolarizer. Theoretical background for both mechanisms is provided. The influence of sample volume, mixing coil parameters (tube length and inner diameter), tube material and flow rate on the separation process is discussed. The separation process dependence on the flow rate may provide the basis of surface active substances characterization. Such characteristics for several surfactants are presented. Under optimized conditions the parameters of the calibration plots for a depolarizer in the absence and presence of surfactant are statistically equivalent. 18 References
Amperometry Optimization Theory

"Anodic Stripping Of Heavy Metals Using A Hanging Mercury Drop Electrode In A Flow System"
Electroanalysis 1998 Volume 10, Issue 10 Pages 701-706
Cecilia Fern&aacute;ndez-Bobes, Maria Teresa Fern&aacute;ndez-Abedul, Agust^iacute;n Costa-Garci&aacute;

Abstract: A hanging mercury drop electrode, included in a low deal volume thin layer flow cell, has been used for on-line simultaneous determination of the trace metals Cd, Pb, Cu and Zn. Parameters related either to the flow system or to the differential pulse anodic stripping technique were optimized. Internal standard and standard additions quantitation methods were tested. Bi was chosen as internal standard and adequate conditions for the stripping medium were studied. The method was applied to the determination of these metals in algae samples of the north coast of Spain. The results compared favorably with those obtained by ICP-MS.
Marine Voltammetry Electrode

"Preconcentration Of Divalent Trace Metals On Chelating Silicas Followed By Online Ion Chromatography"
J. Chromatogr. A 1991 Volume 541, Issue 1-2 Pages 443-452
D. Chambaz, P. Edder and W. Haerdi

Abstract: For online pre-concentration of the cited metals, a titanium pre-column (1.3 cm x 1.7 mm or 5 cm x 2 mm) of ethylenediamine triacetate-bonded silica (prep. described) was used, with adsorption from a mobile phase of 0.1 M acetate buffer (pH 5.0) and desorption with 0.1 M HNO3. The eluate was adjusted to pH 3.0 with 0.5 M tartaric acid for use as mobile phase for HPLC on a column (30 cm x 4 mm) of Nucleosil 10SA with post-column derivatization with 4-(2-pyridylazo)resorcinol in a PTFE coil (3 m x 0.5 mm) and detection at 500 nm. Calibration graphs for Co, Ni, Cu, Zn, Cd and Pb were rectilinear from 3 nM to 3 µM; the method was applied to river water.
River HPIC Spectrophotometry Buffer pH Post-column derivatization Column Preconcentration Chelation

"Determination Of Cadmium And Lead At .mu.g/l Levels In Aqueous Matrices By Chelation Ion Chromatography"
J. Chromatogr. A 1993 Volume 640, Issue 1-2 Pages 207-216
N. Cardellicchio, S. Cavalli, J. M. Riviello

Abstract: Filtered seawater was preserved with concentrated HCl and before analysis was adjusted to pH 5.5 with 2 M ammonium acetate and Cd and Pb were pre-concentrated on a MetPac-CCl column (5 cm x 4 mm) packed with styrene-based macroporous cross-linked iminodiacetate-treated chelating resin (20 µm particles). The Cd and Pb were eluted with 75 mM H2SO4/0.1 M HCl/0.1 M KCl and separated by ion chromatography on an IonPac CS10 column (25 cm x 4 mm) packed with solvent-compatible poly(styrene-divinylbenzene) (8.5 µm particles) agglomerated with ion-exchange latex. The eluent (1 ml/min) was that used for pre-concentration. Post-column derivatization was carried out with 0.3 mM 4-(2-pyridylazo)resorcinol in 1 M 2-dimethylaminoethanol/aqueous 0.5 M NH3/0.5 M NaHCO3 buffer solution and detection was at 520 nm. Calibration graphs were rectilinear up to 500 ng of Cd and Pb. Detection limits were 2 and 6 ng of Cd and Pb, respectively.
Sea HPIC Chelation Post-column derivatization Iminodiacetate Latex Metpac

"Performance Of Solid-membrane Cation-selective Electrodes For Flow Injection Potentiometry"
Sens. Actuat. B 1992 Volume 10, Issue 1 Pages 15-20
L. K. Shpigun, O. V. Basanova and Yu. A. Zolotov

Abstract: The dynamic behavior and the response time characteristics of the solid membrane Ag, Cu, Pb and Cd ISE used as detectors in single-channel flow injection systems are investigated. The potentiometric signal profile depends on the response of the particular electrode, the concentration of the primary ion, the flow rate of the carrier solution and the volume of analyte injected. It is shown that the contact time of the analyte with the electrode (Δt) is particularly important and when designing an flow injection potentiometric system the operating parameter should be adjusted to give a maximum value for Δt. The dynamic behavior of solid-membrane Ag, Cu, Pb and Cd ion-selective electrodes (ISEs) as detectors in a flow injection potentiometric system is described. The predominant role of the dynamic response-time characteristics of the sensors on the potentiometric signal is emphasized. When the value of the dynamic response time τ is smaller than the contact time Δt of the injected primary ion solution zone with the electrode surface, a transient signal is detected and thus τ dramatically affects the linear working range, the electrode response slope and the detection limit. The selectivity properties of the sensors are also dependent on the contact time and usually the potentiometric selectivity coefficients increase with increasing Δt. In each case, the optimal phys. parameters of the flow manifold can be chosen beforehand from the dynamic response-time curves recorded with a given electrode.
Potentiometry Electrode Electrode Electrode Electrode Electrode

"Determination Of Trace Metals In Seawater By Graphite-furnace Atomic Absorption Following Online Separation And Preconcentration"
Spectrochim. Acta B 1993 Volume 48, Issue 1 Pages 91-98
Laerte C. Azeredo, Ralph E. Sturgeon and Adilson J. Curtius

Abstract: The elements Cd, Cu, Fe, Mn, Ni, Pb and Zn were pre-concentrated as their chelates in a flow injection manifold (diagrams given) on a column of silica-immobilized quinolin-8-ol (20 µL) and eluted with 2 M HCl - 0.8 M HNO3 followed by AAS. The recoveries from reference materials were between 92 and 100% with coefficient of variation (n = 4 to 7) from 2 to 12%. The results were close to certified values. Detection limits were from 0.36 to 2.04 ng L-1 for a 5 mL sample.
Sea Spectrophotometry Preconcentration Chelation Reference material Silica 8-Hydroxyquinoline

"Flow Injection Sorbent Extraction With Dialkyl Dithiophosphates As Chelating Agent For The Determination Of Cadmium, Copper And Lead By Flame Atomic Absorption Spectrometry"
Spectrochim. Acta B 1996 Volume 51, Issue 14 Pages 1917-1923
Renli Ma and Freddy Adams*

Abstract: Of the OO-dialkyl phosphorodithioates evaluated for retention of the cited heavy metals on a Perkin-Elmer B050-4047 C18 column containing 20 mg of ODS silica gel (cf. Anal. Chim. Acta, 1994, 285, 33), the best was diethyl phosphorodithioate in the presence of 0.1 M citrate at pH 3 (buffered with ammonium acetate). With loading for 20 s at 8.7 ml/min the enhancement factors for the cited metals were 35, 35 and 26 and the detection limits were 0.8, 1.4 and 10 µg/l, respectively. The method is applicable to digests of environmental, biological and industrial materials.
Environmental Biological Industrial Sample preparation Spectrophotometry Sample preparation Chelation Solid phase extraction C18 Silica gel

"A Comparison Of Preconcentration Reagents For Flow Injection Analysis Flame Atomic Spectrometry"
Spectrochim. Acta B 1996 Volume 51, Issue 14 Pages 1909-1915
G. M. Greenway*, S. M. Nelms, I. Skhosana and S. J. L. Dolman

Abstract: The chelating resins Chelamine and Chelosolve (Fluka), the immobilized-iminodiacetate controlled-pore glass PROSEP Chelating-1 (Bioprocessing Ltd., Consett, UK) and an in-house-prepared immobilized-quinolin-8-ol controlled-pore glass (CPG-8-HQ) were evaluated for rapid online pre-concentration and matrix separation in the flow injection AAS determination of Cd, Cu(II), Mn(II), Ni(II) and Zn in a flow injection manifold designed for rapid matrix separation. With all four materials the matrix-matching of standards for determining the cited heavy metals in seawater was unnecessary. The most suitable material was PROSEP Chelating-1, which, however, showed inferior selectivity to CPG-8-HQ.
Sea Spectrophotometry Preconcentration 8-Hydroxyquinoline Controlled pore glass Iminodiacetate

"Flow Injection Thermospray Sample Deposition For Electrothermal-atomization Atomic Absorption Spectrometry"
Spectrochim. Acta B 1989 Volume 44, Issue 6 Pages 571-579
P. C. Bank, M. T. C. de Loos-Vollebregt and L. de Galan

Abstract: The flow injection thermospray introduction system described previously (Ibid., 1988, 43B, 983) has been modified to obtain more reproducible sample deposition on to the wall of a graphite-tube atomizer. Under optimum conditions, viz, a sample flow rate of 0.7 mL min-1, a thermospray vaporizer temperature of 300°C and a deposition temperature of 120°C in the graphite tube, the sensitivities for Ag, Al, As, Au, Cd, Co, Mn, Pb, Ru and V were identical with those obtained by conventional graphite-furnace AAS. The area of spray-deposited material formed on the wall of the graphite tube is independent of sample volume (unlike conventional manual injection), and thus the flow injection thermospray system can be used over wide analytical ranges. Solutions containing up to 2% of NaCl could be injected without plugging of the thermospray vaporizer capillary.
Spectrophotometry Optimization Interface

"Determination Of Heavy Metals By Inductively Coupled Plasma Mass Spectrometry After Online Separation And Preconcentration"
Spectrochim. Acta B 1998 Volume 53, Issue 11 Pages 1527-1539
Valderi L. Dressler, Dirce Pozebon and Adilson J. Curtius*

Abstract: A method for the determination of Cu, As, Se, Cd, In, Hg, Tl, Pb and Bi in waters and in biological materials by inductively coupled plasma mass spectrometry, after an online separation, is described. The matrix separation and analyte pre-concentration is accomplished by retention of the analytes complexed with the ammonium salt of O,O-di-Et dithiophosphoric acid in a HNO3 solution on C18 immobilized on silica in a minicolumn. Methanol, as eluent, is introduced in the conventional pneumatic nebulizer of the instrument. To use the best compromise conditions, concerning the ligand and acid concentrations, the analytes were determined in two sep. groups. The enrichment factors were at 5-61, depending on the analyte. The limits of detection varied from 0.43 ng L-1 for Bi to 33 ng L-1 for Cu. The sample consumption is only 2.3 mL for each group and the sampling frequency is 21 h-1. The accuracy was tested by analyzing five certified reference materials: water, riverine water, urine, bovine muscle and bovine liver. The agreement between obtained and certified concentrations was very good, except for As. The relatively small volume of methanol, used as eluent, minimizes the problems produced by the introduction of organic solvent into the plasma.
River Urine Muscle Liver Mass spectrometry Interferences Method comparison Reference material Preconcentration C18 Silica Ion pair formation

"Electrothermal Atomic Absorption Spectrometric Determination Of Cadmium And Lead In Blood Using Flow Injection Online Sorption Preconcentration In A Knotted Reactor"
Spectrochim. Acta B 1998 Volume 53, Issue 6-8 Pages 1041-1048
Elissaveta Ivanova, Willy Van Mol and Freddy Adams*

Abstract: A flow injection online sorption separation system combining a knotted reactor (KR) and 2 sorbent extraction columns was developed for the electrothermal atomic-absorption spectrometric determination of (ultra) trace amounts of cadmium and lead in freeze-dried blood samples. The diethyldithiophosphate complexes of the analytes were selectively adsorbed on the inner walls of the PTFE KR. The chelating reagent was online-purified using conical sorbent extraction columns packed with 20 mg of C18 bonded silica gel. The collected analyte complexes were quant. eluted from the 100 cm KR with 35 µL methanol and the eluate was directly introduced into a pyrolytically coated graphite tube pretreated with iridium modifier. Enhancement factors of 26 and 99 and detection limits of 0.2 and 1.6 ng L-1 were obtained for cadmium and lead, respectively. The relative standard deviation was 2.1% for 0.02 µg L-1 cadmium and 2.7% for 0.2 µg L-1 lead. The spike recovery was between 90 and 100%. The results from the anal. of biological reference materials agreed with the certified or indicated values.
Blood Spectrophotometry Preconcentration Knotted reactor Reference material C18

"Critical Evaluation Of A Multi-element Electrothermal AAS System Using Line Sources And A Transversely Heated Graphite Atomizer With Zeeman-effect Background Correction"
Spectrochim. Acta B 1993 Volume 48, Issue 11 Pages 1381-1392
M. Berglund, W. Frech and D. C. Baxter, B. Radziuk

Abstract: The cited system, which consisted of a spatially isothermal transversely heated graphite atomizer (THGA) with integrated platform and Zeeman-effect background correction and mounted in an echelle polychromator, was constructed (diagram given) and evaluated for use in simultaneous multi-element analysis by AAS. By using beam splitters, as many as four line sources could be combined. Under multi-element conditions, characteristic mass values were similar to those obtained with conventional line-source electrothermal AAS with a THGA, although detection limits were about an order of magnitude poorer. This loss of detection was due to low radiation flux through the polychromator and light losses in the optical system. Design modifications are suggested to overcome these problems. A more general disadvantage with line-source AAS is the short working range. The instrument was used to determine Cd, Cu and Pb simultaneously in seawater samples following pre-concentration and matrix separation in a flow injection system (discussed).
Sea Spectrophotometry Preconcentration Matrix removal

"Determination Of Cadmium By Inductively Coupled Plasma Atomic Emission Spectrometry After Suction-Flow Online Preconcentration On 8-Quinolinol-Loaded Active Carbon"
Anal. Sci. 1991 Volume 7, Issue 6 Pages 879-882
Y. OKAMOTO, A. MURATA and T. KUMAMARU

Abstract: A low-cost online pre-concentration system using a column packed with porous active carbon impregnated with 8-quinolinol is described for the determination of Cd by ICP AES. Sample solution at pH 2.5 to 7 was merged with citrate buffer solution (pH 8.5) and pumped through the packed column. Cadmium ions were eluted from the column directly into the nebulizer with 0.5 M HCl for analysis by ICP AES. The calibration graph was rectilinear for 1 g mL-1 of Cd; the detection limit was 0.25 ng mL-1. Sample throughput was 35 h-1. The coefficient of variation (n = 10) for 500 ng of Cd was 1.1%. The method was used to determine Cd in biological materials.
NIES 1 NIST 1566 Mass spectrometry Spectrophotometry Preconcentration Sensitivity Interferences 8-Hydroxyquinoline Activated carbon

"Determination Of Major And Trace-elements For Certified Reference Material Of Riverine Water JAC-0031 And JAC-0032 By ICP-MS"
Anal. Sci. 1997 Volume 13, Issue 2 Pages 177-182
T. SHIMAMURA and M. IWASHITA

Abstract: Element concentrations were determined by ICP-MS for certified reference materials of riverine water JAC 0031 and JAC 0032 which were recently distributed for a collaborative study to determine certified values. Concentrations were determined of nine elements (Mg, Al, Mn, Ni, Cu, Zn, As, Cd and Pb) out of sixteen elements, which were intended to be certified. An additional eleven trace elements (Li, V, Co, Rb, Sr, Mo, Sb, Cs, Pa, W and U) were also determined. The results obtained for the former nine elements generally agreed well with the values from other laboratories and with certified values. The results obtained for the latter eleven elements were consistent with our previous data, which were obtained from our monitoring project for the same river at a nearby sampling point. 39 References
JAC 31 JAC 32 River Mass spectrometry Reference material Method comparison

"Increased Sensitivity Potentiometric Detectors For FIA"
Anal. Sci. 1997 Volume 13, Issue 3 Pages 403-408
C. M. C. M. COUTO, J. L. F. C. LIMA and M. C. B. S. M.MONTENEGRO

Abstract: This paper describes the development of potentiometric detection systems with increased sensitivity for flow injection analysis (FIA). The detection systems are based on homogeneous crystalline membranes which are sensitive to chloride, bromide and iodide anions and copper, cadmium and lead cations. Two types of potentiometric detection systems have been established: one has two tubular electrodes sensitive to the same species placed sequentially, in which one of the electrodes works alternatively as a reference electrode (sequential detector system); the other type comprises a tubular potentiometric detector with two membranes and a conventional reference electrode (double membrane detector system). In the latter, totalling the potentials of each membrane is performed externally using an electronic summing device. The behavior of the two detection systems was evaluated in a low-dispersion FIA manifold. Their characteristics were similar to those of single membrane tubular electrodes, except for the calibration slope, for which a value approximately double was obtained. 23 References
Electrode Electrode Potentiometry Membrane Sensitivity

"Multielement Determination Of Ultratrace Impurities In High Purity Tantalum Metals By Flow Injection/inductively Coupled Plasma Mass Spectrometry"
Anal. Sci. 1998 Volume 14, Issue 4 Pages 757-762
Shuji KOZONO), Hiromu SAKAMOTO), Ryuma TAKASHI) and Hiroki HARAGUCHI

Abstract: A rapid and sensitive method for the determination of impurity elements in high purity tantalum metals is proposed. Tantalum metals were digested with nitric acid (HNO3) and hydrofluoric acid (HF). The digested sample solutions were injected into a flow injection system with a cation exchange column. Impurity elements adsorbed were eluted with the mixture of HNO3 and HF, and then the effluent was introduced into an ICP plasma with conventional pneumatic nebulization. In the present flow injection/ICP-MS system, the detection limits, based on 3 times the standard deviation of the blank, were in the range 0.03-6 ng/g for the 16 impurity elements (Li, Na, Mg, Mn, Co, Cu, Zn, Ga, Rb, Sr, Cd, In, Ba, Tl, Pb, and Bi).
High purity Mass spectrometry Sample preparation Ion exchange Preconcentration

"Reductive Determination Of Metal Ions By Flow Injection Analysis Using Amperometric Amalgam Detectors"
Anal. Proc. 1986 Volume 23, Issue 12 Pages 434-435
D. Eadington and J. A. W. Dalziel

Abstract: A tenfold increase in the sensitivity of a copper-amalgam detector for the cited determination (cf. Alexander and Akapongkul, Anal. Chim. Acta, 1983, 148, 103) is achieved by incorporating a 'wall-jet' working electrode with a larger surface area (28.3 mm2) and smaller cell volume (0.5 µL). Daily restoration of the sensing surface and anodic stripping after each analysis give better reproducibility and permit simultaneous detection of Cu (0 to 20 ppm) and Cd (24 ppm).
Amperometry Electrode Review Simultaneous analysis

"Simultaneous Determination Of Hydride And Non-hydride Forming Elements By Inductively Coupled Plasma Atomic-emission Spectrometry"
Anal. Proc. 1992 Volume 29, Issue 10 Pages 438-439
Zhang Li, Susan McIntosh and Walter Slavin

Abstract: Arsenic, Se, Sb, Bi, Cd, Cr, Cu, Fe, Mn, Ni and Pb were determined in the NIST environmental standard reference materials steel, coal fly ash, urban particulated and 1643b water by ICP-AES. A Perkin-Elmer FIAS-2000 flow injection system was used for hydride generation (experimental conditions tabulated). The sample solution was split into two streams, one being pumped directly to the nebulizer, the other mixed with HCl and NaBH4 solution in the mixing tubes of the chemifold. After separation, the hydride was swept into the spray chamber through a slightly modified cross-flow nebulizer cap. The hydride was then carried into the plasma together with sample aerosol. Recoveries of 20 µg L-1 of As, Sb and Se and 50 µg L-1 of non-hydride forming elements in river- and seawater standards were >80%.
NIST 1643 NIST 1633 NIST 1648 Particulates Alloy Environmental Coal Fly ash River Sea Spectrophotometry Spectrophotometry Reference material FIAS-200 Nebulizer Volatile generation Volatile generation

"Online Immobilized Chelating Agents In Flow Injection Systems"
Anal. Proc. 1993 Volume 30, Issue 11 Pages 438-440
G. M. Greenway, A. Townshend

Abstract: The chelating agents quinolin-8-ol-5-sulfonic acid, dithiocarbamate, dithizone, cysteine and Selenestrum capricornulum were immobilized on to controlled-pore glass particles and packed into columns (4 cm x 2 mm). These columns were incorporated into a flow injection system and sample (5 or 10 ml) was passed through the column. Accumulated metal ions were eluted with 100 µL of dilute HNO3 or HCl, and determined in the eluate by AAS. The flow injection system has a throughput of 20 samples/h. Detection limits and uptake capacities of the chelating agents for Cd, Co, Cu, Hg, Pb and Zn are tabulated.
Spectrophotometry Immobilized reagent Chelation Dithizone Controlled pore glass

"The Use Of Surfactants To Obtain Cadmium Atoms At Room Temperature And Its Application For The Cold Vapor AAS Determination Of The Metal"
Anal. Proc. 1995 Volume 32, Issue 2 Pages 49-52
A. Sanz-Medel, M. C. Vald&eacute;s-Hevia y Temprano, N. Bordel Garc&iacute;a and M. R. Fern&aacute;ndez de la Campa

Abstract: So far, mercury is the only metal that has been proved to be able to form a monoatomic vapor at room temperature. This property has been widely used in analytical techniques, particularly in atomic spectroscopy, where cold vapor atomic absorption spectrometry (CV-AAS) has become the most common method for the determination of low levels of Hg.In this communication we will show evidence that cadmium appears also to be able to form cold atomic vapor in appropriate conditions. Experimental results show that by reduction of Cd2+ with sodium tetrahydroborate in vesicles of didodecyldimethylammonium bromide (DDAB), some volatile cadmium species (probably hydrides) can be produced that transport the metal to the atomic absorption measurement cell, where atomic cadmium vapor has been proved to be present in measurable concentrations.Based on these facts, a new determination of traces of cadmium by cold vapor atomic absorption spectrometry is proposed. Such CV-AAS determination of the metal is very sensitive in normal conditions (detection limit of 0.08 ng ml-1) and the sensitivity can be improved further by working at lower temperatures for generation of the volatile species.
Plant Plant Spectrophotometry Volatile generation Volatile generation

"Optimized Microwave Digestion Procedure For Cadmium Analysis Of Mussel Samples"
Analusis 1998 Volume 26, Issue 7 Pages 261-263
M.C. Yebra and M.F. Enr&iacute;quez

Abstract: A simple and rapid acid sample digestion method by microwave heating in high-pressure teflon bombs is reported for the determination of cadmium in mussels by flame atomic absorption spectrometry (FAAS) coupled online with a flow injection pre-concentration system. Tests concerning the digestion time, the power of the microwaves and the amt. of nitric acid were studied with the National Research Council of Canada lobster hepatopancreas marine (Tort-1) as certified reference material. Using 2 min of digestion time and 2 mL of nitric acid, the complete dissolution of 0.2 g of freeze-dried sample is possible. The anal. results, obtained with calibration graph as well as by the standard addition method, were agreed well with the certified value of the reference material. This procedure was applied to the determination of cadmium in mussel samples from estuaries in Galicia, Spain.
Mussel NRCC TORT-1 Sample preparation Spectrophotometry Reference material Preconcentration Standard additions calibration

"Online FIA Atomic Spectrometry For The Analysis Of Metal Traces"
Ann. Chim. 1995 Volume 85, Issue 7-8 Pages 443-454
MENTASTI E

Abstract: A review is presented, with 28 references. It is concluded that the practical blank-limited detection limit obtainable by flow injection pre-concentration online with atomic spectrometry has nearly been reached, and that the only further possibility (apart from the impractical use of a larger sample volume) is the development of flow injection ICP-MS. Sensitivity of the pre-concentration to the chemical state of the metal indicates the possibility of using flow injection atomic spectrometry for speciation. Online flow injection analysis (online FIA) for the determination of metal traces by atomic spectrometry is reviewed and discussed with reference to environmental applications. The FIA manifold comprises a microcolumn packed with XAD-2 resin which retains the analytes in form of metal complexes. Successive elution enables the achievement of an enrichment step with which very low detection limits can be reached. (28 references)
Sea Mass spectrometry Sample preparation 8-Hydroxyquinoline Chelex Preconcentration Review Solid phase extraction Speciation

"Determination Of Cadmium At The Ppb Level By Column Preconcentration - Atomic Absorption Spectrometry"
Bunseki Kagaku 1986 Volume 35, Issue 2 Pages 106-110
Hirata, S.;Umezaki, Y.;Ikeda, M.

Abstract: A 4 mL sample is injected into a carrier stream (5 mL min-1) of water that then merges with a stream (1 mL min-1) of 0.5 M ammonium acetate buffer and a further stream (2.8 mL min-1) of water before entering a column (1.6 cm x 3.2 mm) of Chelex-100. Stopcocks are arranged to divert the water - buffer stream and to replace the second water stream by an eluent stream of 2 M HNO3 to carry the Cd to the spectrophotometer for measurement at 228.8 nm. The limit of detection is 0.3 ppb and the coefficient of variation (n = 10) at 30 ppb was <1.7%. Tolerance limits are listed; the lowest are 1000-fold amounts of Al, Cu, Ni or Zn and 3000-fold amounts of Fe(II) or Fe(III). Results for NIES No. 1 (pepperbush) agreed well with the certified value.
NIES 1 Spectrophotometry Chelex Reference material Preconcentration

"Application Of FIA For Process Control Of Wet Non-ferrous-metal Refinement"
Bunseki Kagaku 1988 Volume 37, Issue 11 Pages T171-T175
Shimizu, H.;Murakami, M.

Abstract: Flow injection analysis with spectrophotometry or fluorimetry was applied to the determination of Cd, Cu(II), Fe(III), and Ga. Sample solution (25 µL) was injected into a carrier stream (0.65 to 0.7 mL min-1) to mix with the reagent solution (same flow rate) in the reaction coil, which was connected to a flow cell (18 µL) of a spectrophotometer. The carrier and reagent solution (respectively) were : (i) for Cu(II), acetate buffer (pH 5) and 10 µM-4-methyl-5-(sulfoaminoethyl)-2-(thiazol-2-ylazo)benzoic acid, (ii) for Fe(III), water and 2 M HCl and (iii) for Cd, sodium citrate (9 g) - potassium sodium tartrate (5 g) in 500 mL of 0.2 M NaCl, and 0.5 mM cation. Lumogallion and polyoxyethylene glycol dodecyl ether were used as fluorescent reagent and sensitizer, respectively, for the determination of Ga. The absorbance of the complexes of Cu(II), Fe(III) and Cd were measured at 585, 440 and 447 nm, respectively. The fluorescent adduct of Ga was determined at 560 nm (excitation at 485 nm). Interference from Mn(II), Co(II), Cr(III), Cr(VI) and Ni(II) was observed with the determination of Cd. Bivalent Fe, Ca, As(V) and SO42- interfered in the determination of Ga, but Zn, Cd, Fe(II), In and As(III) did not interfere. Calibration graphs were rectilinear for 0 to 5 µg mL-1 of Cu(II), 0 to 10 g L-1 of Fe(III), 0 to 1 mg L-1 of Cd and 0 to 3 µg mL-1 of Ga. The results agreed well with those obtained by AAS for Cu(II) or Cd, or by titration of Fe(III) with KMnO4.
Industrial Calibration Interferences Process control Process control

"Determination Of Cadmium By Ion-chromatography Using 10-(2-pyridylazo)-9-phenanthrol As A Post-column Derivatization Reagent"
Bunseki Kagaku 1993 Volume 42, Issue 5 Pages 311-316
Yoshida, T.;Okawa, S.

Abstract: Sample (20 µL) was injected onto a Shimadzu pack IC-Cl column (15 cm x 5 mm) with 0.25 M lactic acid buffer of pH 3.3 as mobile phase (1 mL min-1) and post-column reaction with 0.2 mM 10-(2-pyridylazo)-9-phenanthrol solution containing 5% dioxan - 4% Brij 35 - 0.0198% Na borate - 0.0214% NaOH (0.3 mL min-1) at pH 10.3. Detection was at 545 nm. The calibration graph was rectilinear from 40 to 200 ppb of Cd and the coefficient of variation (n = 6) was 1.3% (for 80 ppb of Cd). The detection limit was 14.5 ppb of Cd. The cited method was applied to the determination of Cd in standard reference oyster tissue.
Oyster HPIC Post-column derivatization Reference material

"Determination Of Seven Trace Elements In Environmental Water Samples By Inductively Coupled Plasma Mass Spectrometry With Online Preconcentration"
Bunseki Kagaku 1993 Volume 42, Issue 7 Pages 423-428
Akatsuka, K.;McLaren, J.W.;Berman, S.S.

Abstract: An online pre-concentration method was studied to allow the simultaneous determination of Mn, Co, Ni, Cu, Zn, Cd and Pb in 5 mL environmental water samples by inductively coupled plasma mass spectrometry. A semiautomated system with a microprocessor-controlled high performance quaternary gradient pump and valves was used to lead and transport the mobile phase. The system includes a column containing silica-immobilized 8-hydroxyquinoline. The pH of the samples was adjusted to 8 to improve the retention of several elements, in particular manganese. Quantitative elution from the column took 3.5 min with a 1.5 M HCl/0.6 M HNO3 mixture at a flow rate of 2.0 mL min-1. Mn and Co were determined by a standard additions technique, and stable isotope dilution was applied for Ni, Cu, Zn, Cd and Pb. The good precision and accuracy of this method are demonstrated by analyzing standard samples of riverine water (SLRS-2), estuarine water (SLEW-1) and coastal seawater (CASS-2). The detection limits of the method range from 7 ng L-1 for Cd to 130 ng L-1 for Zn. [References: 18]
NRCC SLRS-2 NRCC SLEW-1 NRCC CASS-2 Sea River Mass spectrometry Preconcentration Computer Column Immobilized reagent Silica 8-Hydroxyquinoline Reference material Standard additions calibration

"Sensitive And Precise Analytical Methods For The Determination Of Impurities In Hydrometallurgical Zinc Refining By Utilizing The Flow Injection Technique"
Bunseki Kagaku 1996 Volume 45, Issue 1 Pages 1-18
Hayashibe, Y.;Sayama, Y.;Oguma, K.

Abstract: A flow sheet for a hydrometallurgical zinc-refining process stream is presented, and the typical compositions of the initial and purified electrolyte are tabulated. A block diagram of a computer-controlled FIA system is given, and manifolds are illustrated for the determination of (i) Cu at 810 nm, (ii) Cu at 525 nm with 2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolinesulfonate, (iii) Co at 480 nm with nitroso-R salt, (iv) Co at 617 nm with 3-[3-amino-4-(5-bromo-2-pyridylazo)-N-propylanilino]propanesulfonate, and (v) Cd at 480 nm with cadion and also for a flow injection ICP-MS system. Investigations are reported of (i) the use of a non-dispersed high-volume sample zone to overcome the effects of high salt concentrations, (ii) corrections for system variation and (iii) a computer-controlled variable-volume injector to extend the dynamic range of the system. Finally, the introduction into FIA of online anion exchange to permit the determination of trace metals in high-purity zinc by ICP-MS is discussed.
High purity Ion exchange Spectrophotometry Mass spectrometry Computer Linear dynamic range

"Studies On Rapid And High Performance Analytical Systems For The Process Quality And Quantity Control Of The Non-ferrous Metal-refining Industry"
Bunseki Kagaku 1997 Volume 46, Issue 5 Pages 407-408
Sayama, Y.

Abstract: A brief overview is presented of systems developed in the author's laboratory for (i) the flow injection spectrophotometric determination of Cd, Co and Cu in hydrometallurgical zinc, (ii) the ICP-MS determination of trace impurities in ultra-high-purity zinc, (iii) the HPLC-ICP-AES determination of Sb(III) and Sb(V) in Cu electrolyte, (iv) the ICP-AES determination of trace impurities in high-purity copper, (v) the coprecipitation of metals and electrodeposition of S in copper, and (vi) the first-derivative spectrophotometric determination of rare-earth metals.
Hydrometallurgical Spectrophotometry Review Process control Coprecipitation

"Analysis Of River Water By ICP-MS With Online Preconcentration Using Flow Injection"
Can. J. Anal. Sci. Spectrosc. 1998 Volume 43, Issue 2 Pages 43-48
Beauchemin, D.;Specht, A.A.

Abstract: A flow injection manifold is described for online pre-concentration. of several elements and their determination by inductively coupled plasma mass spectrometry. This manifold incorporates a cleaning column on the buffer line to remove trace contaminants from the buffer prior to its mixing with the sample. A 2 M HNO3 eluent is used to determine elements which suffer from spectroscopic interferences from Cl-containing compounds The pre-concentration. factor can easily be changed by simply modifying the sample loading time (i.e., the amt. of time the sample is pumped through the anal. column). A 30-fold pre-concentration. (using 1.5 mL sample and 50 µL eluent) was used to analyze certified river water, SLRS-2. Under these conditions, sample throughput was ~20 samples/h. Results agreed well with certified values for V, Co, Cd, and Pb using standard additions, and for V, Co, Cd, and Sb using external calibration. Both calibration strategies provided results of similar accuracy and precision, but the latter was far less time-consuming. Trace determination of ubiquitous elements such as Zn is still precluded by a high blank.
River NRCC SLRS-2 Mass spectrometry Reference material Preconcentration Interferences

"Atomic Absorption Spectrometric Determination Of Cadmium, Copper And Zinc In A Flow System Using An Online Preconcentration Technique"
Can. J. Anal. Sci. Spectrosc. 1992 Volume 37, Issue 5 Pages 119-125
Esmadi, F.T.;Khasawneh, I.M.;Kharoaf, M.A.;Attiyat, A.S.

Abstract: Preconcentration was effected by mixing the sample solution and a precipitation reagent in a PTFE mixing coil (5 cm x 1 mm) and pumping the mixture to a Tygon precipitation coil (7 cm x 2.8 mm) packed with borosilicate glass beads (1.9 mm). This coil was washed and a dissolving reagent was introduced to carry the cations to the AAS nebulizer. Reagent concentration, flow rates and residence times in the precipitation coil were optimized for the cited metals. The best precipitation - dissolving reagent combinations for the cited metals were Na2CO3 - H3PO4, Na2S - NaCN and Na2CO3 - HCl, respectively. Calibration graphs were rectilinear up to at least 10 ppm for all three metals. With precipitation for 5 min, the detection limits were 7, 40 and 6 ppb for Cd, Cu and Zn, respectively; compared with direct FIA, these limits were reduced six- to eight-fold. Serious interference was caused by oxalate, Pb(II), F- or CN- present at the precipitation stage. A flow injection analysis technique coupled with a pre-concentration. unit was used to determine cadmium, copper, and zinc. The cation and a pptg. anion were passed for a certain period of time through a Tygon tube containing glass beads and connected to the atomic absorption spectrophotometer (AAS). A suitable dissolving agent was then allowed to pass which dissolved the ppt. and the cation was transported to the AAS, yielding a signal. Cadmium was pptd. as CdCO3 and Cd3(PO4)2 and the dissolving agents for both ppts. were HClO4, HCl, and H3PO4. Zinc was pptd. as ZnCO3 and dissolved in NH3, NaCN, and HCl, whereas copper was pptd. as CuS and dissolved in NaCN. The pre-concentration. time was varied and as it increased, the sensitivity increased. The results of the determination of the cations using the FIA technique with pre-concentration. were compared with those using the conventional FIA technique when the pre-concentration. times were 1, 3, and 5 min. The lowest detection limits obtained were 0.007 ppm Cd when it was pptd. as CdCO3 and dissolved in H3PO4, 0.006 ppm Zn when it was pptd. as ZnCO3 and dissolved in HCl, and 0.004 ppm Cu when it was pptd. as CuS and dissolved in NaCN. The method proved to be simple and precise, consumption of chemical reagents was low and sample throughput was high.
Spectrophotometry Preconcentration Precipitation Glass beads Optimization Interferences

"Nafion-coated Mercury-coated Glassy-carbon Electrodes For Metals Analysis And Speciation"
Can. J. Chem. 1987 Volume 65, Issue 5 Pages 1133-1138
Robert D. Guy and Sarath Namaratne

Abstract: The properties of mercury-coated glassy carbon electrodes coated with a thin membrane of Nation 117 were studied to evaluate the potential analytical applications in metal ion analysis. The Nation membrane was found to contain two types of binding sites - a strong site that bound metal ions in a nonelectroactive form and cation exchange sites that were useful for pre-concentrations prior to differential pulse voltammetry. The exchange constants for the weak sites ranged from 0.413 for copper to 12.5 for methyl viologen. The differential pulse currents were increased by a factor of 75 to 100 and a linear calibration curve was observed from about 25 n M to 1000 n M for copper, lead, cadmium, and zinc. The ion exchange reaction is very sensitive to ionic strength and significant enrichments occur only in solutions of ionic strength below 0.10. The Nafion-coated glassy carbon electrode in a flow cell can be used to determine the free copper ion concentration in samples by a combination of ion exchange and differential pulse voltammetry. The flow-through system required about 15 mL of sample solution and an analysis time of about 10 min. The ion exchange measurement gave a linear calibration from 40 nM to 10 µM for free copper.
Electrode Electrode Ion exchange Voltammetry Preconcentration Speciation

"Determination Of Trace Heavy Metals By Flow Injection Analysis With Adsorptive Stripping Voltammetric Detection"
Chem. Anal. 1995 Volume 40, Issue 1 Pages 1-12
Strozik, M.;Kubiak, W.W.;Kowalski, Z.

Abstract: Sample solutions based on NH3/NH4Cl buffer (200 µL; containing Pb and Cd) were treated with 80 µM-oxine and injected into a 0.01 M NH3/NH4Cl buffer carrier solution of pH 9.5. After a delay time for the sample to reach the cell, pre-concentration was started at -300 mV. The delay and pre-concentration times are dependent on the flow rate and the sample volume, e.g., for a 200 µL sample with a flow rate of 0.71 ml/min, the delay was 5 s and the accumulation time was 20 s. After accumulation, the negative differential pulse potential scan was started; with a scan rate of 40 mV/s and a pulse amplitude of 50 mV. Measurements were made with a fresh Hg drop and without stopping the flow. The detector was homemade based on a PAR model 310 polarographic detector and used with a hanging-Hg-drop detector; a SCE and Pt auxiliary electrodes were immersed with the detector in the supporting electrolyte. Calibration graphs were linear from 2.50 nM-Cd and 20-250 nM-Pb with detection limits of 1 nM-Cd and 4.9 nM-Pb. Interferences are discussed and the method was applied to river water.
River Voltammetry Interferences Apparatus 8-Hydroxyquinoline

"Flow Injection - Flame Atomic Absorption Spectrometric Determination Of Trace Levels Of Cadmium With Online Preconcentration By Means Of Coprecipitation"
Chem. Anal. 1995 Volume 40, Issue 3 Pages 361-371
Wei Min, R.;Hansen, E.H.

Abstract: Sample containing 200 mg/l Fe(III) was injected into a stream of 2% ascorbic acid in 0.2 M KCl containing HCl and carried through a mixing coil (30 cm x 0.7 mm i.d.) before merging with a stream of 0.2% hexamethylene ammonium hexamethylene dithiocarbamate in water containing LiOH. The solution passed through a knotted reactor (300 cm x 0.5 mm i.d.) where the Cd-Fe(II) coprecipitate was collected. The precipitate was eluted with IBMK and injected into a stream of 0.1 M HNO3 for passage to the AAS nebulizer for determination of Cd at 228.8 nm. The dissolution of the precipitate in a discrete zone was preferable to continuous elution. The FIA manifold is illustrated diagramatically and the time sequencing of the three pumps used is described in detail. The calibration graph was linear for 0.5-20 µg/l Cd and the detection limit was 0.074 µg/l. The RSD were 1.75-1.81%.
Spectrophotometry Knotted reactor Preconcentration MIBK Coprecipitation

"Investigations Into Use Of An Auxiliary Metal Ion For Indirect Amperometric Detection"
Chromatographia 1988 Volume 25, Issue 3 Pages 162-166
Barisci, J.N.;Wallace, G.G.;Riviello, J.M.

Abstract: Metal ions were separated by ion chromatography on a Dionex Basic Chromatography module in conjunction with a Dionex HPIC-CS5 ion-exchange column. The mobile phase was 4 mM pyridine-2,6-dicarboxylic acid(I) - 2 mM Na2SO4 - 15 mM NaCl, adjusted to pH 4.8 with LiOH. Post-column derivatization was effected with Na bis-(2-hydroxyethyl)dithiocarbamate and Zn(NO3)2 in 0.1 M NaNO3. Detection was with a vitreous-carbon working electrode vs. a Ag - AgCl (3 M NaCl) reference and a platinum auxiliary electrode. The limit of detection ranged from 0.05 ppm for Cd to 1.30 ppm for Ni. The addition of Zn to the post-column derivatization reagent displaced the analyte metal ions from the I complexes in the chromatographic eluate, with enhancement of analyte sensitivity.
Amperometry HPIC Electrode Complexation Post-column derivatization Indirect

"Integrated FIA - HPLC Method For Preconcentration And Determination Of Transition Metal Ions"
Chromatographia 1992 Volume 34, Issue 9-10 Pages 445-449
P. Richter, J. M. Fern&aacute;ndez-Romero, M. D. Luque de Castro and M. Valc&aacute;rcel

Abstract: Transition and heavy metals (Cd, Co, Cu, Mn, Ni, Pb and Zn) in water were determined by pre-concentration. within a flow injection manifold (details given) comprising two injection valves in series, the loop of valve 1 containing 0.1 M HNO3 and the loop of valve 2 containing a Chelex-100 (ammonium form) micro-column through which a portion of the sample was passed. The loop of valve 1 was opened into valve 2, the concentrated metals were eluted quantitatively onto an HPLC column (25 cm x 4.6 mm) of Ultrabase C18 (5 µm) and were then eluted with aqueous 50 mM tartaric acid and 2 mM sodium octanesulfonate (pH 3.5). Post-column derivatization was with 0.1 mM 4-(2-pyridylazo)-resorcinol monosodium salt in 0.4 M ammonia - 0.2 M ammonium acetate buffer and detection at 500 nm. Calibration graphs were rectilinear from 2 to 200 ng mL-1 with detection limits of 2 to 6.6 ng mL-1 (transition metals) and 24.4 ng mL-1 (Pb). Recoveries were 97.1 to 108.5% and coefficient of variation (n = 11) were 1.6 to 5.1%. An automatic method based on the combination of a flow injection (FI) manifold with a liquid chromatograph has been developed for the enrichment and determination of transition metal ions in water samples. Alternatively, the FI configuration can be used as a screening system for the determination of the total concentration of heavy metals. Two-parameter expressions for calibration graphs involving pre-concentration time and concentration. of the analytes were established for both the FIA and the integrated FIA/HPLC methods. The pre-concentration time depends on the concentration. level of the analytes in the samples. The method is linear in the range 2-200 ng/mL, with RSD values between 1.5 and 5.0. It has been applied to the determination of copper, lead, zinc, nickel, cobalt, cadmium, and manganese in synthetic water samples.
Environmental HPLC Spectrophotometry Chelex Post-column derivatization Preconcentration

"Trace Analysis Of Heavy Metals In Seawater. Flow Injection Analysis And Atomic Absorption Spectrophotometry"
Dan. Kemi 1983 Volume 64, Issue 3 Pages 68-70
Olsen, S.

Abstract: A flow injection anal.-at. absorption spectrometric method for the determination of heavy metals in fjord waters is described. The method is used to monitor the disposal of ore flotation tailings in a Greenland fjord. (SFS)
Sea Ion exchange Spectrophotometry

"Online Column Preconcentration And Determination Of Trace Elements By Flow Injection Inductively Coupled Plasma - Atomic-emission Spectrometry"
Fenxi Huaxue 1993 Volume 21, Issue 12 Pages 1410-1413
Peng, X.J.;Jiang, Z.C.;Zeng, Y.N.

Abstract: Sample solution was treated with 13.4 µM-meso-tetrakis-(4-sulfophenyl)porphyrin and ammoniacal buffer of pH 9.24 before dilution with water and heating at 100°C for 30 min. The mixture was applied at 1 ml/min to a column of silica gel (10-40 µm) and elution was effected with 2 M HCl. The eluate was sprayed directly into the spectrograph for ICP-AES analysis for Cu, Mn, Ni, Fe, Pd and Cd. The detection limits for these elements were 0.32-26.8 ng/ml and the RSD (n = 6) were 1.3-3%. No interference was observed from co-existing ions. The enrichment factor was 9.3-11.3 and the sampling rate was 12 runs/h. The method was employed in analysis of bovine liver and tomato leaves reference materials.
Liver Leaves Spectrophotometry Preconcentration Reference material Silica gel Column Interferences

"Flow Injection Online Preconcentration-graphite Furnace Atomic Absorption Spectrometry For The Determination Of Cadmium, Copper, And Nickel"
Fenxi Huaxue 1998 Volume 26, Issue 6 Pages 715-718
Su, X.;Zhang, H.;Jin, Q.;Chen, M.;Zou, M.;Wang, D.

Abstract: The flow injection online pre-concentration system is combined with graphite furnace atomic absorption spectrometry. Bonded silica gel with octadecyl functional group (C18) was used as column-packing material. Na diethyldithiocarbamate was used as chelating agent and EtOH was used as eluent. Based on the way of volume-controlled eluent zone sampling, the enrichment factors for the determination of Cd, Cu and Fe are 40, 29 and 18, respectively. The detection limits (3s) are 0.4, 3.0 and 22 µg/L for Cd, Cu and Fe, respectively.
Spectrophotometry Preconcentration C18 Silica gel Chelation Diethyldithiocarbamate

"Simultaneous Spectrophotometric Determination Of Lead And Cadmium By Flow Injection-charge-coupled Device-diode Array Detection"
Fenxi Huaxue 1998 Volume 26, Issue 7 Pages 843-846
Li, Y.;Yang, J.;Zheng, X.;Ha, Y.;Hu, J.

Abstract: A flow injection-CCD diode array detection-spectrophotometric setup was established for simultaneous determination of lead and cadmium with meso -tetra (4-trimethylammoniumphenyl) porphine. The linear ranges of Cd and Pb were 0~2.0 mg/L and 0~2.5 mg/L, respectively. The detection limit was 0.014 mg/L for Cd and 0.015 mg/L for Pb. The sampling rate was 60 samples/h. The proposed method has been successfully applied to the simultaneous determination of lead and cadmium in synthetic samples and soaking solution of ceramics. The recovery of spiked samples was from 86.0% to 106.0%, and the relative standard deviation was less than 8.8%.
Ceramics Spectrophotometry Simultaneous analysis

"Flow Injection Online Preconcentration With Active Carbon Fibre For Multi-element Determination In Water Samples Using ICP-AES"
Fenxi Kexue Xuebao 1995 Volume 11, Issue 2 Pages 16-20
Lin Yongjing; Gong Zhenbin; Zhuang Zhixia; Deng Zhiwei; Wang Xiaoru

Abstract: The FIA manifold systems for online column flows are shown schematically for pre-concentration and elution regimes. For the determination of Zn, Pb, Ni, Cd and Mn in mineral and seawater, an appropriate amount of the sample was mixed with 1 mL acetic acid/NH4 acetate buffer solution of pH 7 and 3 mL 0.05% quinolin-8-ol. Portions of the solution were injected at 3.1 ml/min on to columns (11-20 mm x 2.2-3.6 mm) of active carbon fiber and the analyte metals were eluted with 3 M HNO3 at 2.7 ml/min. Portions of eluate were injected into the ICP operating with an RF frequency of 27.15 MHz, an RF power of 1.2 kW, carrier gas of 1 l/min and observation height of 15 mm. The recoveries were 97.5-107.2% and the detection limits were 0.2-4 ng/ml.
Mineral Sea Spectrophotometry Preconcentration 8-Hydroxyquinoline Column Carbon fiber

"Determination Of Cadmium In Human Blood Using A Flow Injection Graphite-furnace AAS System With Online Preconcentration By Dithizone (DTZ) Coprecipitation"
Fenxi Shiyanshi 1992 Volume 11, Issue 6 Pages 5-9
Dong, L.P.;Fang, Z.L.

Abstract: Sample (1 ml) was placed in a PTFE crucible, treated with 6 mL of HNO3 - HClO4 (10:1) and heated at 170°C to near dryness. The residue was transferred into a 15 mL polyethylene tube with hot water, mixed with 1 drop of 1% thiosalicylic acid, the solution was adjusted to pH 2 to 3 with sodium acetate saturated solution and treated dropwise with 2% ascorbic acid until the red color disappeared. After addition of 3 drops of 2% ascorbic acid, the solution was diluted to 10 mL with water. The solution was used for online pre-concentration. by DTZ co-precipitation and flow injection graphite - furnace AAS (flow diagram and procedure program given). Detection limit was 3 µg mL-1 of Cd with coefficient of variation (n = 7) of 2.6%. The results obtained compared well with certified values.
Whole Sample preparation Spectrophotometry Coprecipitation Preconcentration Reference material Dithizone

"Simultaneous Flow Injection Analysis - Spectrophotometric Determination Of Zinc And Cadmium In The Presence Of Mixed Surfactants"
Fenxi Shiyanshi 1992 Volume 11, Issue 6 Pages 27-29
Qi, W.B.;Chen, X.M.

Abstract: The synergic sensitizing effect of hexadecyltrimethylammonium bromide (I) - Peregal O [polyoxyethylene glycol mono-octadec-9-enyl ether] on the color system Zn or Cd - 4-(2-pyridylazo)-resorcinol (PAR), was studied. Total amounts of Zn and Cd were determined by flow injection analysis (details given). For individual determinations, Cd was masked with diethyldithiocarbamate, Zn was determined directly and Cd concentration. was calculated by difference. Beer's law was obeyed for up to 0.6 µg g-1 of Zn and up to 1 µg g-1 of Cd. The method was applied in the analysis of natural waters. Recoveries were 97 to 100%.
Environmental Spectrophotometry Differential detection Surfactant

"Study On Applicability Of Trace Element Determination In Solution With High Salt Concentration By FIA-flame AAS"
Fenxi Shiyanshi 1993 Volume 12, Issue 4 Pages 19-22
Yuan, Y.;Guo, X.W.

Abstract: A pre-concentration system (schematic diagram given) was developed for flame AAS and applied to the determination of Pb in Cu metal, and Ag and Cd in geological samples. For determination of Ag and Cd in ore, sample (2 g) was digested with 10 mL of 1:1 aqua regia by heating, the solution was evaporated to ~5 ml, mixed with 0.5 mL of 1% gelatin before dilution with water to 10 mL. The solution was analyzed by the cited method with 1% aqua regia as carrier stream. The detection limits were 0.02 µg/g of Ag and 0.01 µg/g of Cd; RSD (n = 23) were 0.5%.
Metal Geological Spectrophotometry Preconcentration

"The Direct Determination Of Cadmium In Urine By Flow Injection Online Ion-exchange Preconcentration Flame Atomic Absorption Spectrometry"
Fenxi Shiyanshi 1993 Volume 12, Issue 6 Pages 55-57
Dong Liping and Fang Zhaolun

Abstract: Urine (3.5 ml) was acidified with 35 µL of concentrated HNO3 and adjusted to pH 3 with aqueous NH3 or dilute HNO3. The sample solution (3.5 ml) was merged online with 0.5 M ammonium acetate buffer solution (pH 9, 0.3 ml/min) and applied to a conical column packed with CPG-8HQ ion-exchanger; Cd was eluted with 2 M HCl (5 ml/min) directly into the nebulizer of a flame AAS instrument for determination of Cd at 228.8 nm. An enrichment factor of 30 was obtained at a sampling frequency of 60/h. The detection limit was 0.3 ng/ml. The RSD (n = 11) for 40 ng/ml of Cd was 1.5%. Results for a reference standard sample agreed well with reported values.
Urine Spectrophotometry Preconcentration

"Online Determination Of Trace Heavy Metals In Waters By ICP-AES Using A Recycling Nebulizing System With Flow Injection Solvent Extraction"
Fenxi Shiyanshi 1996 Volume 15, Issue 5 Pages 66-68
Cheng, X.H.;Zhou, J.M.;Liu, H.D.;Tang, Z.Y.;Shuai, Q.;Jin, Z.X.

Abstract: Sample (20 ml), was adjusted to pH 1 with HNO3 and heated for 10 min and cooled. The cooled solution was adjusted to pH 2.5 with ammonia water, 0.5 mL aqueous 2% ammonium 1-pyrrolidinecarbodithioate was added and the pH was re-adjusted to 2.5 with 5% HNO3. The mixture was diluted to 25 mL with water and a 240 µL portion of the diluted solution was injected into the flow injection liquid-liquid online extraction system of Shuai et al., (Dizhi Shiyanshi, 1996, in press), using an extraction coil (1.5 m x 0.8 mm i.d.) over 75 s, with IBMK for removal of metal impurities. The organic phase was transferred to the recycling nebulizing system for ICP-AES. Detection limits for Cd, Co, Cu, Fe, Mo, Ni and V were 0.1-2.2 µg/l, with RSD 3.2-7.6%. Recoveries were 93.5-104%. Sampling frequency was 20 runs per h.
Environmental Spectrophotometry Sample preparation Nebulizer MIBK Solvent extraction

"Preconcentration Of Trace Metals For Their Determination With ICP-AES"
Fortschr. Atomspektrom. Spurenanal. 1984 Volume 1, Issue 1 Pages 491-499
Vos, Gerrit; Van Dordrecht, Peter; Ten Bras, Petrus W. (SFS)

Abstract: Trace metals were determined in natural waters by inductively coupled plasma atomic emission spectroscopy (ICP-AES) after pre-concentration by ion exchange or solvent extraction Chelex 100 [11139-85-8] gave better recoveries of Mn, Co, Ni, Cu, Zn, Cd, and Pb than Amberlite IR 120 [9002-23-7] or 8-hydroxyquinoline [148-24-3] immobilized on SiO2. However, CHCl3 extraction with 4-ethyl-1,2,4-triazole [43183-55-7]/Na diethyldithiocarbamate (I) [148-18-5] or ammonium pyrrolidinedithiocarbamate [5108-96-3]/I gave better results. (SFS)
Environmental Ion exchange Spectrophotometry Sample preparation Preconcentration Solvent extraction Chelex Amberlite 8-Hydroxyquinoline Diethyldithiocarbamate Pyrrolidine dithiocarbamate

"Simultaneous Determination Of Trace Amounts Of Mercury, Cadmium And Zinc By Ion Chromatography Using M-tetrakis(4-sulfophenyl)porphyrin [TPPS4] As Post-column Derivatization Agent"
Gaodeng Xuexiao Huaxue Xuebao 1990 Volume 11, Issue 2 Pages 136-139
Yan, D.;Zhang, J.;Schwedt, G.

Abstract: The cited determination was carried out with use of TPPS4 as derivatization agent, 4-(2-pyridylazo)resorcinol in Na2B4O7 - NaOH buffer (pH 10.3 to 12) containing NaCl as the derivatization catalyst and tartaric acid - NaCl as mobile phase. A chemically bonded silica gel cation-exchanger was used as the stationary phase and the separation was completed in 10 min. The method was applied to the analysis of waste water, silicate and corn samples.
Waste Silicate Corn HPIC Post-column derivatization Buffer pH Catalysis

"Simultaneous Multi-element Analysis And Matrix Effect Of Sodium Chloride By Flow Injection ICP-AES"
Guangpuxue Yu Guangpu Fenxi 1991 Volume 11, Issue 5 Pages 32-37
Zhang, Z.;Zeng, X.

Abstract: The determination of Cd, Cr, Fe, Mn, Ni, V, Ca, Co, Cu, Mg and Zn by ICP-AES combined with flow injection analysis. The best coefficient of variation and detection limits were obtained with 5- or 10-s integral times. The effects of a NaCl matrix on the elements were studied. The results show that the flow injection technique could reduce analytical signal drift and improve determination reproducibility. The matrix effects of NaCl varied with different r.f. power and the matrix effect of NaCl existed mainly in the evaporation - atomization - excitation process in the ICP.
Inorganic compound Spectrophotometry Multielement Signal drift Interferences

"Study Of The Effects Of Matrix And Acid In Flow Injection ICP-AES"
Guangpuxue Yu Guangpu Fenxi 1992 Volume 12, Issue 3 Pages 49-54
Chen, H.;Jiang, Z.C.;Zeng, Y.N.;Kong, L.Y.

Abstract: To study matrix and acid effects in flow injection ICP-AES, a PGS-2 plane-grating spectrograph was used (working conditions tabulated). Results showed that the introduction of 5 mg mL-1 of matrices (viz. Na, Ca, Fe and Zn) and acids (viz. HCl, HNO3 and H2SO4) caused a decrease in emission intensity of Cr, Mn, Ni, Cu, V, Cd and Zn, but no significant change in excitation temperature and electron density was observed. The matrix interference could be eliminated by adding an appropriate amount of the matrix elements into the carrier.
Spectrophotometry Interferences

"Determination Of Trace Cobalt, Nickel And Cadmium By Online Flow Injection Analysis With Coprecipitation Preconcentration Flame AAS"
Guangpuxue Yu Guangpu Fenxi 1994 Volume 14, Issue 1 Pages 85-90
Dong, L.P.;Fang, Z.L.

Abstract: Ox liver (0.2 g) or urine (10 ml) was placed in a PTFE crucible, treated with 3 mL of HNO3/HClO4 (10:1) and the mixture was heated at 170°C to near dryness. The residue was treated with ~15 mL of hot water, the solution was mixed with 100 µL of 1% Fe(III) and 1 drop of 1% thiosalicylic acid. The solution was adjusted to pH 3 with saturated sodium acetate solution, mixed dropwise with 2% ascorbic acid until the red color disappeared, treated with 3 drops of the reagent in excess and water to 10 mL. The solution was fed at 2 ml/min into a FIA system (diagram given). Co, Ni and Cd were co-precipitated with ammonium pyrrolidinedithiocarbamate-Fe complex, the precipitate was dissolved with methyl isobutyl ketone and the solution was introduced into a Perkin-Elmer atomic absorption spectrophotometer. The detection limits of Co, Ni and Cd were 1, 3 and 3 ng/ml, respectively. The RSD were 2.3% for 20 ng/ml of Co, 2% for 100 ng/ml of Ni and 2.4% for 10 ng/ml of Cd. Results agreed with the certified values.
Liver Urine Spectrophotometry Reference material Preconcentration Coprecipitation MIBK

"Application Of Intermittent-flow Hydride-generation Sample Introduction To Hydride-generation AAS/AFS"
Guangpuxue Yu Guangpu Fenxi 1995 Volume 15, Issue 3 Pages 97-101
Guo, X.W.;Guo, X.M.

Abstract: The design, construction and operation of the cited hydride-generator were described (details given) and applied to the determination of Te by AAS and Zn and Cd by AFS. The detection limits were 0.12 and 0.02-1.22 ng/ml, respectively, with RSD of 0.8 and 0.67-1.05%, respectively. The results from this method were compared with those obtained by flow injection, continuous-flow and intermittent sample introduction techniques. Advantages of this setup were less cross-contamination, ease of operation, flexible sampling amounts and low running costs.
Fluorescence Spectrophotometry Method comparison Volatile generation Volatile generation

"Determination Of Trace Amount Of Cadmium And Lead In Human Hair Using A Flow Injection FAAS System With Online Preconcentration"
Huanjing Huaxue 1995 Volume 14, Issue 2 Pages 169-173
Chen, Shuyu; Zhang, Min; Lin, Shuqin; Peng, Zicheng

Abstract: A method to determine trace amounts of cadmium and lead in human hair was developed by coupling flow injection analysis with flame atomic absorption spectrometry (FAAS). In acidic solution, cadmium and lead are extracted into Methyl iso-Butyl ketone (MIBK) by ammonium pyrrolidinedithiocarbonate (APDC) in the extraction coil and detected by FAAS. The sensitivity of determination and sampling frequency may be improved greatly, while possible interferences may be effectively removed at the same time. The relative standard deviation was 3.4% (n=9) at 0.20 mg/mL. The sensitivity may be increased 21 times for Cd and 23 times for Pb. Cd and Pb recovery was 87.3%-97.0% and 91.9%-107.3%, respectively. Choices of experimental parameters were investigated; results obtained with some hair samples are consistent with literature values.
Hair Spectrophotometry Preconcentration Interferences Extraction Organic solvent Optimization

"Flame Atomic Absorption Spectrometric Determination Of Copper, Lead, Cadmium, And Manganese In Natural Waters Using A Flow Injection System With Online Ion Exchange Preconcentration"
Huanjing Kexue 1995 Volume 16, Issue 5 Pages 54-56
Wang Peng

Abstract: The title method was developed, and some practical considerations in the design of online column pre-concentration FIA system for FAAS were studied. The relative standard deviation was about 2.0% (n=11) at a sampling frequency of 45 h-1 with an enrichment of around 20 times. The advantages, such as high-efficiency, online, accuracy, precision, micro-amount of sample, automation et al., made it possible to be applied to the routine analysis of natural waters.
Environmental Spectrophotometry Speciation Preconcentration Precision

"Automatic Flow Injection Analysis System For The Extraction - Kinetic Studies"
Huaxue Tongbao 1991 Volume 54, Issue 5 Pages 30-32
Chen, T.;Zhang, G.;Zhang, H.

Abstract: The cited system is equipped for continuous potentiometric or spectrophotometric detection, in which the sampling and data processing are controlled by a Laser 310 microcomputer with use of a program in BASIC (diagram given). For practical application, the apparatus with potentiometric detection is utilized for analysis of Cd by extraction - kinetic study using a Cd(II) - 8-hydroxyquinoline - CHCl3 system; for Ce determination, spectrophotometric detection using a Ce(III) - 2-ethylhexyl hydrogen phenylphosphate - CHCl3 system and 0.01% arsenazo III as chromogenic reagent was used with measurement at 655 nm.
Potentiometry Spectrophotometry Sample preparation Computer Kinetic 8-Hydroxyquinoline Extraction Chromogenic reagent

"Determination Of Zinc, Cadmium, Lead And Copper In Precipitation By Computerized Differential Pulse Voltammetry"
Int. J. Environ. Anal. Chem. 1985 Volume 19, Issue 2 Pages 85-98
Lingerak, W.A.;Van Wensveen Louter, A.M.;Slanina, J.

Abstract: A computerized flow injection analysis - differential pulse anodic-stripping voltammetric system is described and illustrated. Rain-water samples are made 0.2 M in HNO3 and filtered through Ederol 69K activated-carbon-impregnated filters, which retain organic matter; the metals are carried by buffered electrolyte solution to the flow-through cell, with a mercury-drop electrode, for deposition and anodic stripping. The system is controlled by an Apple II computer (details given). From 12.4 to 56.6 ppb of Zn, 0.18 to 0.76 ppb of Cd, 4.9 to 32.7 ppb of Pb and 0.8 to 7.9 ppb of Cu were determined by means of a calibration graph without the need for standard additions, and results were in agreement with those obtained by AAS. Application of the method to seawater, surface water and acid digests of biological samples is discussed.
Biological Rain Sea Surface Electrode Sample preparation Voltammetry Computer Method comparison

"Sorption Preconcentration And Flow Injection Determination Of Cadmium"
J. Anal. Chem. 1998 Volume 53, Issue 9 Pages 796-799
I. A. Gur'ev and N. V. Kuleshova

Abstract: A procedure for the flow injection determination of Cd traces in aqueous solutions was developed. The procedure is based on the use of ion-selective electrodes sensitive to chloride or iodide complexes of Cd. Sorption pre-concentration simultaneously transforms Cd to anal. active species, it decreases the limit of detection, and improves the selectivity of determination.
Electrode Electrode Potentiometry Indirect Complexation Selectivity

"Multi-channel Photometric Detector For Multi-component Analysis In Flow Injection Analysis"
J. Autom. Methods Manag. Chem. 1994 Volume 16, Issue 2 Pages 71-73
AIMIN TAN, JIALIN HUANG, LIUDI GENG, JINHUA XU, and XINNA ZHAO

Abstract: A multi-channel detector which can simultaneously monitor more than one flow-cell at multiple wavelengths for multi-component analysis has been developed. The detector contains up to four flow-cells each equipped with dual wavelength light-emitting diodes (LED) and photo transistors as light source and detector. The LED are switched on and off under computer control and the light measured by the photo transistor and amplifier. The absorbance for each wavelength and cell was calculated by a single-chip microcomputer. The absorbance of a 1 x 10^-5 g/ml bromothymol blue solution was measured at 630 nm and 565 nm with a RSD of 0.25% and 0.24% respectively. The performance was demonstrated from the simultaneous determination of Co and Cd in zinc sulfate electrolyte, producing comparable results to those obtained by traditional methods.
Zinc sulfate Spectrophotometry Multichannel Computer Photodiode Light emitting diode Method comparison

"Micro-column High-pressure Liquid Chromatography With A Glass-frit Nebulizer Interface For Plasma Emission Detection"
J. Chromatogr. Sci. 1985 Volume 23, Issue 4 Pages 144-150
Mona Ibrahim, Wipawan Nisamaneepong and Joseph Caruso

Abstract: Microcolumn high pressure liquid chromatography (micro-HPLC) is rapidly gaining recognition as a practical separation tool for organometallic compounds. The use of the inductively coupled plasma (ICP) as a detector for micro-HPLC is studied. Several miniaturized glass-frit nebulizers are investigated as interfaces between the output of the microbore column and the ICP torch. Their performance with aqueous and methanolic solutions is evaluated by direct nebulization and flow injection analysis. The most efficient of these nebulizers is used in the micro-HPLC/ICP study of some Cd, Pb, and Zn organometallic compounds. Detection limits of 1.92 ng of Pb for tetramethyllead and 5.01 ng of Pb for tetraethyllead are obtained and compared with regular HPLC/ICP of these same compounds. Approximately equivalent detection limits were obtained when using a microwave induced plasma as an alternate plasma source. Several miniaturized glass-frit nebulizers were investigated as interfaces between the outlet of the micro-bore column and the ICP torch. Their performance was evaluated by using aqueous and methanolic solution of Cd with direct nebulization and flow injection analysis. The most suitable nebulizer was used in micro-HPLC of some organometallic Cd, Pb and Zn compounds, on a reversed-phase column of C2 material. Detection limits of 1.92 ng of Pb for tetramethyl-lead and 5.01 ng of Pb for tetraethyl-lead were obtained. These were compared with results of regular HPLC - ICP analysis; similar results were obtained with use of a microwave-induced plasma.
HPLC Spectrophotometry Method comparison Nebulizer Optimization

"Low-cost Flow Injection Analysis For Cadmium Using 2-(2-Benzothiazolylazo)-4,5-dimethylphenol"
J. Environ. Sci. Heal. 1991 Volume 26, Issue 1 Pages 63-74
Kate Grudpan & Chusri Palsaludomsil

Abstract: 2-(2-benzothlazolylazo)-4,5-dlmethylphenol (BTDMP) has been applied as a new color reagent to flow Injection analysis (FIA) for cadmium. The low-cost FIA system used was made and assembled using low-cost and easily available materials. Optimum conditions for the FIA system were Investigated, such as analytical wavelength, a solvent as a carrier, alkalinity of the carrier, concentrations of reagents used, flow-rate and mixing coil length. Using the optimum conditions, a calibration curve was obtained for a linear range of 0-10 ppm Cd. Interferences of some metal ions (Zn, Cu, Co, Nl and Hg) were studied.
Spectrophotometry Low cost Interferences Optimization

"Determination Of Cadmium Of Ppb Level By Column Preconcentration-atomic Absorption Spectrometry"
J. Flow Injection Anal. 1986 Volume 3, Issue 1 Pages 8-17
S. Hirata, Y. Umezaki and M. Ikeda

Abstract: A method utilizing a miniature ion-exchange column of Chelex-100 has been developed to increase the sensitivity for cadmium measurement by atomic absorption spectrometry (AAS) . Separate samples (pH 2-5) are mixed with ammonium acetate buffer (pH 7), pumped through a column and sequentially eluted with 2 M nitric acid directly to the AAS by using a flow injection analysis (FIA) system. This method gives cadmium detection limit which is over 15 times better than that for conventional continuous aspirated system and 0.3 ppb (S/N=2), by using 4 mL of a sample solution. Precision of the method is better than 1.7% RSD (n=10) at the 30 ppb level for aqueous standards and the sampling rate is 24 samples h-1. This method was successfully applied to the analysis of a biological standard reference material (Pepperbush, NIES No. 1).
Spectrophotometry Column Preconcentration

"Circulating Solvent Extraction System For Trace Metals In Aqueous Solution"
J. Trace Microprobe Tech. 1989 Volume 7, Issue 1-2 Pages 103-110
Yoshimura, E.;Toda, S.

Abstract: Sample solution containing the chelated analyte is mixed with organic solvent in a funnel, the tapering end of which is packed with pieces (2 mm x 1 mm) of porous PTFE film to break any emulsion. The two-phase percolate meets a porous PTFE bobbin phase separator (6 cm x 1 cm diameter) through which only the organic phase passes, the aqueous phase being returned by a pump to the funnel. The organic phase drips into a vessel containing magnetically stirred acidic aqueous back-extractant, wherein the analyte is concentrated while the organic phase is sucked through a further PTFE phase separator (4 cm x 1 mm diameter) to a solvent reservoir from which solvent is pumped to the funnel. For 0.1 µg mL-1 each of Zn and Cd chelated with diethyldithiocarbamate in a 2-l sample, respective concentration. factors of 51 and 34 were attained with use of 70 mL of CHCl3 and 20 mL of 1 M HCl. Projected improvements to the system are briefly discussed.
Sample preparation Chelation Emulsion Phase separator Organic solvent Solvent extraction

"Flow-through Atomic Absorption Determination Of Metals After Enrichment"
Magy. Kem. Foly. 1992 Volume 98, Issue 8 Pages 323-329
Graf Harsanyi, E.;Feher, Z.

Abstract: Mini-columns (3 cm x 2.5 mm) packed with 40 mg of silica gel (30 to 50 µm; pore diameter 10 nm) containing quinolin-8-ol were used for off-line enrichment of Pb, Cd and Cu in aqueous solution at pH 4 to 6. A 100-fold concentration. of Pb was possible in 20 min with 5% HNO3 as eluent (3.8 mL min-1) . The flow injection apparatus described gave rectilinear calibration graphs from for 0.01 to 0.1 µg mL-1 of Pb and 0.005 to 0.05 µg mL-1 of Cd and Cu; the coefficient of variation was 5.1%.
Spectrophotometry Column Silica gel Preconcentration 8-Hydroxyquinoline pH

"A Mechanized Continuous-flow System For The Concentration And Determination Of Cobalt, Copper, Nickel, Lead, Cadmium, And Iron In Seawater Using Graphite Furnace Atomic Absorption"
Mar. Chem. 1990 Volume 29, Issue 1 Pages 33-46
Kenneth B&auml;ckstr&ouml;m and Lars-G&ouml;ran Danielsson

Abstract: Details are given of an extraction manifold (illustrated) in which the sample is mixed with an extraction reagent containing 0.3% each of ammonium pyrrolidine-1-carbodithioate and diethylammonium diethyldithiocarbamate in 0.75 M NaHCO3 and extracted with 1,1,2-trichloro-1,2,2-trifluoriethane in a falling drop segmentor before passage through an extraction coil and a phase separator. The organic phase is treated with a solution (1 mg mL-1) of Hg in 0.07 M HNO3 as stripping reagent in a second segmentor, the mixture then passes through a second extraction coil and separator. The resulting aqueous back-extract is collected in the sample injector (23 µL) of the interface described previously (Anal. Chem., 1988, 60, 1354) for injection into a Varian AA-1275 instrument equipped with a GTA-95 graphite-tube atomizer; pyrolytically coated graphite tubes (Varian 63-100008-00) with a small internal barrier are used. Temperature programmes for each metal are specified, and contamination problems are summarized. Operation is fully automated apart from loading the sample cups. Sample throughput is 30 h-1. Results on a seawater reference material agreed with certified values for, Co, Cu, Ni and Pb, but were slightly high for Cd and Fe.
Sea Spectrophotometry Sample preparation Extraction Automation Reference material Phase separator

"Automated Monitoring Of Nickel, Copper, And Zinc In The Irish Sea"
Mar. Pollut. Bull. 1996 Volume 32, Issue 6 Pages 471-479
Eric P. Achterberg* and Constant M. G. van den Berg

Abstract: The distributions of Ni, Cu and Zn have been monitored in the Irish Sea using fully automated voltammetric instrumentation and collection of seawater by underway pumping. The continuous real-time measurements provided high resolution data with a minimum risk of sample contamination, The surveys showed that the River Mersey was a significant contributor of Ni, Cu and Zn to the eastern Irish Sea and that the trace metal distribution was consistent with an anti-clockwise residual water movement in the eastern Irish Sea. The automated instrumentation is very useful for monitoring requirements for environmental impact assessments and can provide high resolution trace metal data for marine modeling purposes. Copyright (C) 1996 Elsevier Science Ltd,[16 References]
Sea River Voltammetry Remote instrument

"Determination Of Lead And Cadmium In Food Samples By Flow Injection Atomic Absorption Spectrometry"
Quim. Anal. 1987 Volume 6, Issue 1 Pages 52-59
Becerra, G.;Burguera, J.L.;Burguera, M.

Abstract: Samples are dried at 105°C, then wet-ashed with 30% H2O2 solution at 50°C and subsequently at 110°C after adding HNO3. The solution is evaporated and the residue is dissolved in 0.1 M HNO3 before analysis with a flow system as described by Fukamachi and Ishibashi (Anal. Chim. Acta, 1980, 119, 383) and air - acetylene flame AAS. Standards are analyzed similarly and peak heights are measured and averaged. Detection limits for a 10-g sample are 0.23 and 0.05 µg g-1 of Pb and Cd, respectively. Results obtained on NBS bovine liver and oyster tissue agreed well with the certified values.
Food NIST 1566 NIST 1577 Sample preparation Spectrophotometry Reference material

"Online Trace Metal Enrichment In Flow Injection Atomic Absorption Spectrometry"
Quim. Anal. 1989 Volume 8, Issue 2 Pages 159-170
Devi, S.;Habib, K.A.J.;Townshend, A.

Abstract: Aqueous samples containing Cu2+, Cd2+, Mg2+, Zn2+, Pb2+ and Hg2+ were pre-concentrated on a mini-column of 8-hydroxyquinoline-5-sulfonic acid immobilized on to controlled-pore glass and eluted with HNO3 or HCl (depending on the metal to be analyzed) directly into a nebulizer for AAS analysis. Calibration graphs were rectilinear from 0 to 100, 100 to 1000, 20 to 220, 10 to 100, 10 to 300 and 20 to 2000 ng mL-1 of Cd2+, Pb2+, Zn2+, Mg2+, Cu2+ and Hg2+, respectively; detection limits ranged from 0.5 ng mL-1 (for Cu) to 25 ng mL-1 (for Hg). . The coefficient of variation ranged from 1.1 to 2.9% (n = 4). Aqueous samples containing Cu2+, Cd2+, Mg2+, Zn2+, Pb2+ and Hg2+ were pre-concentrated on a mini-column of 8-hydroxyquinoline-5-sulfonic acid immobilized on to controlled-pore glass and eluted with HNO3 or HCl (depending on the metal to be analyzed) directly into a nebulizer for AAS analysis. Calibration graphs were rectilinear from 0 to 100, 100 to 1000, 20 to 220, 10 to 100, 10 to 300 and 20 to 2000 ng mL-1 of Cd2+, Pb2+, Zn2+, Mg2+, Cu2+ and Hg2+, respectively; detection limits ranged from 0.5 ng mL-1 (for Cu) to 25 ng mL-1 (for Hg). . The coefficient of variation ranged from 1.1 to 2.9% (n = 4).
Spectrophotometry Column Controlled pore glass Nebulizer Calibration Detection limit 8-hydroxyquinoline-5-sulfonic acid

"Spectrophotometric Flow Injection Screening Analysis Of Foodstuffs For Lead And Cadmium Exploiting Ion Association"
Quim. Anal. 1996 Volume 15, Issue 2 Pages 161-166
Piedade Sartini, R.;Gomes Neto, J.A.;Silva Lopes, T.I.M.;Zagatto, E.A.G.

Abstract: The method was based on formation of ternary complexes between Pb(II) or Cd(II) with iodide and Malachite green (MG). Sample (500 µL) was injected into a 0.05 M HNO3 carrier stream (3.2 ml/min) which merged (i) a mixture of 1 M ammonium acetate/1 mM picolinic acid/0.2% 1,10-phenanthroline buffer (0.4 ml/min) and 1.2 mg/l Pb (0.4 ml/min) and (ii) a mixture of 0.5 mM MG (0.4 ml/min) and 2 M KI/0.3% L(+)-ascorbic acid (0.4 ml/min). Detection was by absorbance measurement at 690 nm. Calibration graphs were linear for up to 500 µg/l Pb and 150 µg/l Cd and detection limits were 10 and 2 µg/l, respectively. At concentrations of less than 100 µg/l Pb and 25 µg/l Cd the analytical signals were additive and hence the method could be used to screen HNO3/H2O2 digests of foodstuffs for Pb and Cd. The sampling rate was 70/h. To determine Pb, a pre-concentration Chelex-100 column was coupled to the FIA manifold and the retained Pb was eluted with 0.3 M HNO3. With this modified manifold the linear range was 10^-250 µ/l Pb and the detection limit was 4 µg/l. The sampling rate was 45/h. Results were precise (RSD
Food Spectrophotometry Chelex Column Preconcentration

"Pneumatic Nebulizer As A Dilution Chamber In A Flow Injection System For Multielement Analysis By ICP-MS"
Quim. Nova 1998 Volume 21, Issue 4 Pages 405-409
Gomes Neto, Jos&eacute; Anchieta; Silva, Jos&eacute; Bento B.; Rodrigues Neto, Renato; Curtius, Adilson Jos&eacute;; Souza, Ivan G.

Abstract: An automatic dispenser based on a flow injection system used to introduce sample and anal. solution into an inductively coupled plasma mass spectrometer through a spray chamber is proposed. Anal. curves were constructed after the injection of 20 to 750 µL aliquots of a multielement standard solution (20.0 µg L-1 in Li, Be, Al, V, Cr, Mn, Ni, Co, Cu, Zn, As, Se, Sr, Ag, Cd, Ba, Tl, Pb) and the acquisition of the integrated transient signals. The linear concentration. range could be extended to ~five decades. The performance of the system was checked by analyzing a NiST 1643d reference material. Accuracy could be improved by the proper selection of the injected volume Besides good precision (relative standard deviation <2%), the results obtained with the proposed procedure were closer to the certified values of the reference material than those obtained by direct aspiration or by injecting 125 µL of several anal. solutions and samples.
NIST 1643 Mass spectrometry Dilution Nebulizer Reference material

"Ion-chromatographic Determination Of Total Metals In Soils"
Soil Sci. Soc. Am. J. 1990 Volume 54, Issue 5 Pages 1289-1297
N. T. Basta and M. A. Tabatabai*

Abstract: Surface soil samples (2 g) were digested sequentially with concentrated HNO3, HClO4 and HF. The HF treatment was repeated until dissolution was complete. An aliquot (25 ml) of the resulting solution was treated with ammonium citrate buffer (5 ml), hydroxylammonium chloride solution (2 ml) and pyridine (2.5 ml). The solution, pH adjusted to 9.5 with 10 M NaOH, was extracted with 0.2% of dithizone in CHCl3 (2 x 15 ml). The combined extracts were evaporated to dryness and the residue was treated with concentrated HNO3 (3 ml) and again heated to dryness. The residue was dissolved in 0.1 M HCl and analyzed on a HPIC-CS 5 column equipped with a HPIC-CG 5 guard column with buffered 4 mM 2,6-pyridinedicarboxylic acid (pH 4.8) or 40 mM oxalic acid (pH 4.8) as mobile phase (1 mL min-1). Post-column derivatization was achieved by mixing the column effluent with a stream of 0.01% ammoniacal solution of 4-(2-pyridylazo)resorcinol and 0.02% NN-dimethylethanolamine; the absorbance of the metal complexes was measured at 520 nm. Results obtained for Cu, Ni and Zn agreed with those obtained by AAS; low results were obtained for Cd, Mn and Pb. With oxalic acid as eluent, the detection limits were 5 µg L-1 for Cu and Zn and 20 µg L-1 for Ni; the coefficient of variation were 4.9% (n = 6).
Environmental HPIC Sample preparation Spectrophotometry Buffer Column Post-column derivatization Detection limit Method comparison Complexation Dithizone

"Analysis Of Chromium, Nickel, Cadmium And Lead In Food Samples By Flow Injection ICP-MS"
Spectrosc. Eur. 1997 Volume 9, Issue 1 Pages 10-NA
Harrington, C.F.;Fairman, B.E.;Catterick, T.

Abstract: Oyster tissue (CRM 1566 a) was wet oxidized using concentrated oxidants by high pressure microwave digestion. The digests were made up to 100 mL so that they contained 7% HNO3 and 2% H2O2. FIA was used (schematic given); the digest was delivered at a flow rate of 4.4 ml/min and mixed with 0.5 ng/g Rh (internal standard). Nitric acid was the carrier solution at a flow rate of 6.1 ml/min. Measurements were carried out using an Elan 5000 ICP-MS instrument with a forward power of 1050 W; the flow rates for the coolant, intermediate and nebulizer were 15, 0.8 and 0.9 l/min, respectively. Pt sampler and skimmer cones and a cross-flow nebulizer were used throughout. The operating pressure was 9 x 10^-6 torr. A proficiency testing sample (WRC aquacheck 101) was analyzed by the system to check the accuracy, recoveries were closer to 100% Cr, Ni and Cd than for a conventional method. Results for the oyster CRM are tabulated; lower % errors were obtained by the FIA than by a conventional method.
NIST 1566 Mass spectrometry Sample preparation Method comparison Reference material

"Application Of Removal Of Dissolved Oxygen By Silicone Membrane To Flow Amperometric Detector"
Toyama Diagaku Kyoikugakubu Kiyo 1986 Volume 34, Issue 1 Pages 1-7
Hara, Minoru; Nomura, Noboru; Yamaguchi, Kikuko; Matsubara, Naomi (SFS)

Abstract: Considerable amounts of dissolved oxygen in aqueous solutions were continuously removed by passing the solutions through a silicone tubing kept in nitrogen atmosphere. The silicone-tubing system, enclosed with nitrogen jacket, was examined in flow polarography and flow injection analysis systems, and over 90% of oxygen in air-saturated aqueous solutions was removed through a 2 m silicone tubing 1.0 mm i.d. The effects of flow rate and tubing size were also studied.
Amperometry Polarography Silicone membrane Optimization

"Rapid Determination Of Trace Cadmium In Waste Water By FIA - Fluorimetry"
Yankuang Ceshi 1991 Volume 10, Issue 3 Pages 200-202
Guo, J.;Zhao, H.;Duan, X.

Abstract: Industrial waste water adjusted to pH 7 by addition of ammonia, water and acetic acid flowed to react with a stream of 0.7 mM 8-hydroxyquinoline-5-sulfonic acid, 0.65 mM hexadecyltrimethylammonium bromide and ammonium acetate buffer of pH 7.18 in a 29.2-m reaction tube before measuring fluorescence intensity at 534 nm (excitation at 391.7 nm) in a 9.8-cm quantitation tube. Linear range was from 0 to 5 µg mL-1 of Cd. Recovery was 95.2 to 98.7%; coefficient of variation was 0.1%. The rate was up to 180 per h. Only Al3+, Fe3+, Hg2+, Zn2+, Cl-, F- and ClO4- interfered. Results were satisfactory and comparable with those of ICP-AES.
Waste Fluorescence Buffer Interferences pH 8-hydroxyquinoline-5-sulfonic acid

"Determination Of Cadmium By Flow Injection Spectrophotometry With M-tetrakis-[4-(trimethylammonium)phenyl] Porphine"
Yejin Fenxi 1993 Volume 13, Issue 2 Pages 8-11
Shen, Hanxi; Liu, Liuzhan; Yang, Junjiao

Abstract: A new two-channel flow injection system (diagram given) for determination of Cd with the cited reagent as color reagent is described. The carrier stream (4.5 mL min-1) was 0.1 M NaOH (pH 13) and the reagent (20 mM) flow rate was 1.2 mL min-1. Detection was performed at 432 nm vs. a mixed solution of the reagent and the carrier stream. The calibration graph was rectilinear up to 3.5 µg mL-1 of Cd and the relative error was 3% for a synthetic sample. Fe(III) and Hg(II) interfered.
Spectrophotometry Multichannel Interferences

"Bubbleelectrodes - New Flow-through Electrodes For Analytical, Preparative And Spectroscopical Applications"
Z. Chem. 1985 Volume 25, Issue 4 Pages 121-125
Fritz Scholz, G&uuml;nter Henrion

Abstract: A review is presented, with 22 references, in which the theory and applications of bubble electrodes are discussed. Such electrodes find applications in electrolysis, e.s.r., and detection in HPLC or flow injection analysis.
Electrode Voltammetry Review

"Automated System For Rapid Flow Injection Extraction - Atomic Absorption Spectrometric Analysis Of Heavy Metals In Solutions"
Zavod. Lab. 1996 Volume 62, Issue 12 Pages 26-28
Kirko, E.V.;Sorokina, N.M.;Galdina, N.N.;Tsizin, G.I.;Zolotov, Y.A.

Abstract: The apparatus consisted of a peristaltic pump, two injection valves, an extraction column and an AAS instrument controlled by a computer. Samples were applied to the extraction column, the heavy metals were eluted with 2 M HNO3 and the eluate was analyzed by AAS. The column was regenerated periodically with 1 M ammonium acetate buffer. The extraction column, of ~0.1 mL capacity, contained a weak cross-linked polystyrene resin with diethylenetriaminetetra-acetate groups. The flow-through the column was 2-10 ml/min. The limits of detection of Cd, Co, Cu, Mn, Ni, Pb and Zn using the system described were 20-50 times lower than the limits obtained by direct AAS determination. The RSD were Up to 40 samples/h could be analyzed.
Spectrophotometry Sample preparation Column Resin Solid phase extraction

"Dynamic Behaviour Of Solid Membrane Electrodes, Reversible To Silver, Lead And Cadmium Cations, In Flow Injection Systems"
J. Anal. Chem. 1989 Volume 44, Issue 9 Pages 1640-1646
Shpigun, L.K.;Bazanova, O.V.

Abstract: A method, based on potential - time graphs, was developed to estimate the system parameters of Ag-, Pb- and Cd-selective electrodes with solid polycrystal membranes in a one-channel flow injection system. Relationships were found between the analytical signal and the system parameters, which determine the time of sample contact with membrane surface. The potentiometric selectivity of the electrodes is a funcion of time; a shorter contact time (of electrode membrane to sample) means a better potentiometric selectivity.
Electrode Electrode Electrode Electrode Potentiometry Selectivity

"Electrochemical Behavior And Application Of Cadmium-selective Electrode In Water-organic Solvents"
J. Anal. Chem. 1989 Volume 44, Issue 9 Pages 1854-1858
Davydova, S.L.;Chervina, L.V.;Shpigun, L.K.;Radchenko, A.F.

Abstract: The electrochemical behavior of a Cd-selective electrode has been investigated vs. a calomel electrode (with 10% LiClO4 solution as salt bridge) in a test solution containing 0.1 M to 0.1 M Cd(NO3)2 in aqueous DMSO, DMF, ethanol (I), 1,4-dioxan and acetonitrile (II); the linear response range and slope differ for each solvent and vary with its concentration. Use of aqueous DMSO, DMF or I is satisfactory for direct potentiometry; potentiometric titrations with EDTA can be carried out in water or aqueous DMSO, DMF, I or II, but errors are lower with aqueous DMSO, DMF or I than with II or with water alone. The electrode has been applied to the determination of Pt, Pd or Rh in organic compounds or complexes. The sample is dissolved in the organic solvent and the solution is diluted with 20% hexamine buffer solution and water (to give 50% of water in the mixture), a known volume of 10 mM EDTA is added, and excess of EDTA is titrated with 10 mM Cd(NO3)2. The coefficient of variation is 1.5%.
Electrode

"Determination Of Cadmium In Fertilizer By Atomic Absorption Spectrometry After APDC-MIBK Extraction In Continuous-flow"
Zhongguo Kexue Jishu Daxue Xuebao 1990 Volume 20, Issue 1 Pages 61-66
Zhao Huazhang, Lars-Goran Danielsson, Folke Ingman

Abstract: In a modified extraction-atomic absorption spectrometric system, APDC was mixed with MIBK and the mixture passed through a 5 cm segment coil before being mixed with acid-digested fertilizer solution in a 2.5 m extraction coil. The organic extract was led through a phase separator into an air/acetylene flame atomic absorption spectrometer. The APDC concentration was 0.2% for Cd determination and 0.5% for determination of seven other elements. Fe at >0.5 mg in 50 mL of solution interfered with Cd determination, but KI (2 mL, 30%) could mask at least 3 mg Fe. The detection limit for Cd was 1 ppb. Sensitivity was increased 23-fold for Cd and 11-17 fold for the other elements in comparison with results obtained by flame spectroscopy with direct aspiration of aqueous solution. The relative standard deviation was 1.9%, and recovery of added Cd was 98%.
Commercial product Spectrophotometry Sample preparation Extraction MIBK

"Development Of An Ultrasonic Nebulizer Using A Domestic Humidifier"
Bull. Korean Chem. Soc. 1999 Volume 20, Issue 11 Pages 1277-1280
Pyung Heum Yeon, Young Min Cho, and Yong-Nam Pak*

Abstract: An inexpensive ultrasonic nebulizer (USN) was developed utilizing a home humidifier. The ultrasonic transducer was taken from a commercial USN and the power supply was from a humidifier. Sample was continuously fed into the nebulizer and the detection limit was improved 3-20 times over a pneumatic nebulizer. Undesirably, noise in signal was also increased several times. 0.5 ppm of Mn was used as an internal reference and the 'long-term' drift could be successfully corrected. Since the noise contained high and low frequency components, both could be effectively removed only by the real-time correction method such as the Myer-Tracy method, where the reference line was simultaneously monitored with the analytical lines. The performance of USN was tested with NIST SRMs and showed good agreement with the certified values.
NIST 1566 NIST 1547 Mass spectrometry Apparatus Nebulizer Optimization

"Microanalytical Flow-through Method For Assessment Of The Bioavailability Of Toxic Metals In Environmental Samples"
Anal. Bioanal. Chem. 2005 Volume 381, Issue 2 Pages 438-444
Modupe Jimoh, Wolfgang Frenzel and Volkmar M&uuml;ller

Abstract: The application of a recently proposed microanalytical flow-through system for on-line sequential extraction of heavy metals from solid samples of environmental interest is described. Using various extraction schemes (a nitric acid scheme, a two-stage extraction scheme using two reagents applied in the BCR procedure) and comparison with the common batch sequential BCR procedure, the suitability of the system for fast screening of solid environmental samples is demonstrated. By pumping leaching agents sequentially through the sample held in a µcartridge, the different metal fractions present can be assessed in less than an hour. Method evaluation was performed using SRM 1648 urban particulate matter and BCR 701 lake sediment reference material certified for extractable metals. The need for and design of laboratory internal reference material suitable for simulating the natural (dynamic) processes of metal release into the environment is also discussed. For the first time correlation is sought between fractionation techniques and physiologically based methods for assessment of the bioaccessibility of metals in biomatrices.
NIST 1648 BCR 701 Spectrophotometry Mass spectrometry Reference material Method comparison Extraction

"The Online Removal Of Dissolved Oxygen From Aqueous Solutions Used In Voltammetric Techniques By The Chromatomembrane Method"
Anal. Bioanal. Chem. 2002 Volume 374, Issue 7-8 Pages 1256-1260
Regina Reinke and J&uuml;rgen Simon

Abstract: The applicability of the chromatomembrane method for the removal of dissolved oxygen from solvents used in voltammetric measurements was investigated. The chromatomembrane cell combined with a flow-through system allows an online deaeration of solutions. These experiments employed a mercury film electrode as working electrode and differential pulse anodic stripping voltammetry as the measuring method. Different eluents with adequate supporting electrolyte (without analyte) were measured to determine the background current, whether any contribution of oxygen is detectable. Voltammograms of eluents deaerated with the chromatomembrane method are compared to those of eluents purged with nitrogen for several minutes immediately before the measurement. No differences in the background currents can be observed when defined flow rates of eluent and nitrogen are maintained. Determinations of cadmium and lead even indicate the high efficiency of this method.
Electrode Chromatomembrane

"Application Of Flowing Stream Techniques To Water Analysis: Part III. Metal Ions: Alkaline And Alkaline-earth Metals, Elemental And Harmful Transition Metals, And Multielemental Analysis"
Talanta 2004 Volume 63, Issue 2 Pages 201-223
Manuel Mir&oacute;, Jos&eacute; Manuel Estela and V&iacute;ctor Cerd&agrave;

Abstract: In the earlier parts of this series of reviews [1 and 2], the most relevant flowing stream techniques (namely, segmented flow analysis, continuous flow analysis, flow injection (FI) analysis, sequential injection (SI) analysis, multicommuted flow injection analysis and multisyringe flow injection analysis) applied to the determination of several core inorganic parameters for water quality assessment, such as nutrients and anionic species including nitrogen, sulfur and halogen compounds, were described.In the present paper, flow techniques are presented as powerful analytical tools for the environmental monitoring of metal ions (alkaline and alkaline-earth metals, and elemental and harmful transition metals) as well as to perform both multielemental and speciation analysis in water samples. The potentials of flow techniques for automated sample treatment involving on-line analyte separation and/or pre-concentration are also discussed in the body of the text, and demonstrated for each individual ion with a variety of strategies successfully applied to trace analysis. In this context, the coupling of flow methodologies with atomic spectrometric techniques such as flame atomic absorption spectrometry (FAAS), electrothermal atomic absorption spectrometry (ETAAS), inductively coupled plasma mass spectrometry (ICPMS) or hydride-generation (HG)/cold-vapor (CV) approaches, launching the so-called hyphenated techniques, is specially worth mentioning.
Environmental Review

"On-line Preconcentration And ICP Determination For Trace Metal Analysis"
Microchim. Acta 1989 Volume 99, Issue 3-6 Pages 247-255
Valerio Porta, Corrado Sarzanini and Edoardo Mentasti

Abstract: The use of a closed-loop on-line enrichment procedure in combination with an ICP plasma emission spectrometer has been developed for the analysis of trace metal ions, such as Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn. The procedure utilizes a pre-concentration column filled with an anion exchange resin and 8-hydroxy-7-iodoquinoline-5-sulphonic acid is added to the sample prior to pre-concentration. Details on the optimization of pretreatment and instrumental conditions are described. Results obtained for the analysis of river water and antarctic seawater are reported.
Sea River Spectrophotometry Preconcentration Column Resin Closed loop

"Interferences Removal For Cadmium Determination In Samples With Complex Matrices By Hydride Generation Coupled With Non-dispersive Atomic Fluorescence Spectrometry"
Anal. Sci. 2006 Volume 22, Issue 1 Pages 123-126
Zhongxi Li And Liping Zhou

Abstract: An intermittent on-line concentration and separation system coupled with HG-AFS was developed to eliminate serious interferences from Cu2+, Pb2+ and Zn2+ on the determination of cadmium. In the present method, the interferences from common coexisting ions, such as Cu2+, Pb2+, Zn2+, Fe3+ and Ni2+, were greatly reduced. Under the optimized conditions, a detection limit of 3 pg mL-1 (3 s, n = 11) and a precision of 1.9% RSD for 1 ng mL-1 of Cd were obtained. The method was successfully applied to the determination of cadmium in a series of Chinese Geological Reference Materials (SRMs) and GBW01621 ferronickel alloy using simple aqueous standard calibration technique. The results obtained were in good agreement with the certified values.

"Sample Introduction Assisted By Compressed Air In Flame Furnace AAS: A Simple And Sensitive Method For The Determination Of Traces Of Toxic Elements"
Anal. Bioanal. Chem. 2005 Volume 382, Issue 8 Pages 1826-1834
Harald Berndt, Erika Pulvermacher

Abstract: The power of detection of flame AAS for the toxic elements Cd, Hg, Pb and Tl can be improved by 1-2 orders of magnitude by using flame furnace AAS. In flame-furnace AAS, liquid samples are introduced directly into a nickel tube located in the flame, in the simplest case through a ceramic thermospray capillary. Transportation of the samples is achieved by using compressed air only. Comparatively low detection limits are achieved by both beam injection flame furnace (BIFF-AAS) and thermospray flame furnace AAS (TS-FF-AAS). For TS-FF-AAS, a pressure of less than 20 kPa (<80 in. water) is required. The TS-FF-AAS technique is very simple, robust and cheap. The detection limits were 0.2-0.4 µg L-1 (Cd), 40-100 µg L-1 (Hg), 5-9 µg L-1 (Pb) and 4-14 µg L-1 (Tl), respectively, depending on the method, flow rate and sample volume used. Pb and Cd were found at concentrations of 0.1-2 and 0.005-0.3 µg g-1, respectively, in samples of various spices.
Spectrophotometry Spectrophotometry Spectrophotometry Detection limit Pump pressure