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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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Ultratrace

Classification: Feature -> Ultratrace

Citations 49

"Application Of A Stopped-flow Time-difference Technique To Spectrophotometric Determination Of Ultratrace Levels Of Phosphate"
Anal. Chim. Acta 1987 Volume 203, Issue 1 Pages 35-42
Ken-Ichiro Kanaya* and Keitaro Hiromi

Abstract: Optimum conditions, interfering substances, and comparisons with other methods are described for a spectrophotometric method for phosphate, which is based on the stopped-flow technique and involves recording the progress curve for formation of the colored complex of 12-molybdophosphate with malachite green. Linear calibration plots were obtained for phosphate in the ranges 5-55 and 100-1000 g L-1. The sensitivity and the running speed of the method crucially depend on the sulfuric acid concentration. The positive interferences of several anions, especially arsenate, thiosulfate, stannate, tungstate and iodide, are significantly less than in conventional methods. Results for total phosphorus in several foodstuffs agreed with results obtained by a molybdovanadophosphoric acid method.
Phosphate Spectrophotometry

"Determination Of Ultratrace Levels Of Cobalt By Ion-chromatographic Separation And Chemiluminescence Detection"
Anal. Chim. Acta 1989 Volume 221, Issue 2 Pages 249-258
Hiroyuki Sakai, Terufumi Fujiwara, Manabu Yamamoto and Takahiro Kumamaru

Abstract: Separation from interfering components was carried out on a TSK gel IC-Cation-SW column (5 cm x 4.6 mm); the column was attached to a flow injection analyzer., with 3 mM BaCl2 adjusted to pH 3 with dilute HCl as the mobile phase (1 mL min-1). The column eluate was mixed with the reagent stream, consisting of a mixture of aqueous 20 mM H2O2 and 1 mM luminol in 20 mM NaOH (each 0.5 mL min-1). The chemiluminescence of the final mixture was measured and the effect of pH on its intensity was investigated. The detection limit was 1 pg mL-1 of Co; calibration graphs were rectilinear from 10 pg mL-1 over six orders of magnitude. The method was applied in the analysis of the primary coolant of a boiling-water reactor and commercially prepared copper standard solution intended for use in AAS determinations.
Cobalt Water Chemiluminescence

"Ultratrace Determination In High-purity Molybdenum And Tungsten With Ion Chromatographic Trace-matrix Separation. 3. Ultratrace Analysis Using Atomic Spectrometry"
Anal. Chim. Acta 1992 Volume 258, Issue 1 Pages 109-122
A. Seubert

Abstract: Ultratrace anal. of Mo and W using direct coupling of ion chromatography (IC) trace-matrix-sepns. (SMT) and inductively coupled plasma atomic emission spectrometry (ICP-AES) as an atomic spectrometric detection technique is described. The right choice of the nebulizer unit of the ICP system and appropriate chromatography eluents and flow-rates result in a stable, highly sensitive detection system IC-SMT-ICP. The characteristics of ICP-AES as a chromatography detection method and the application of internal standaridization during the measurement of a transient signal are discussed. The importance of the integration time for the registration of transient signals is pointed out. Every elution peak should be covered by 8-16 data points. The final comparison with known batch procedures for trace-matrix-sepns. demonstrates the clear advantage of the combined method IC-SMT-ICP with direct coupling of ion chromatography and atomic spectrometry.
Metals, trace High purity High purity HPIC Spectrophotometry

"Determination Of Ultratrace Concentrations Of Tin By Adsorptive Cathodic Stripping Voltammetry On A Glassy Carbon Mercury Film Electrode"
Anal. Chim. Acta 1992 Volume 270, Issue 1 Pages 143-152
Samuel B. O. Adeloju* and Fleurdelis Pablo

Abstract: A sensitive and selective method is described for the determination of ultratrace concentrations. of tin by adsorptive cathodic stripping voltammetry on a glassy carbon mercury film electrode. The method involves a controlled pre-concentration. by accumulation of tin-catechol complexes on the electrode followed by stripping voltammetric measurement in the cathodic direction. The optimum conditions for the determination of tin by this method include the use of a rotating electrode at 1920 rpm, 0.10 M acetate buffer electrolyte (pH 4.2-4.7), 5 x 10^-4 M catechol, and an accumulation potential of -0.20 V vs. Ag/AgCl. A linear concentration. range is obtained from 0 to 35 µg/L and the limit of detection is 0.5 µg/L for an accumulation period of 300 s. An interference study with various metal ions indicated that these substances generally do not interfere with the tin determination, except for Cu, Cd, and Cr. The interference of Cu and Cd is eliminated by the addition of 1 x 10^-6 M EDTA into the solution The interference of surface-active organic substances, e.g., Triton X-100, is overcome by UV irradn. of the sample for 2 h. The method was successfully employed for the determination of tin in fruit juices. Comparison of the results obtained for the juices demonstrated reasonable agreement with those obtained by atomic absorption spectrometry.
Tin Fruit Voltammetry Electrode Electrode Electrode

"Automated Determination Of Mercury At Ultratrace Level In Waters By Gold-amalgam Preconcentration And Cold Vapor Atomic-fluorescence Spectrometry"
Anal. Chim. Acta 1993 Volume 282, Issue 1 Pages 109-115
Chris C. Y. Chan and Ram S. Sadana

Abstract: Sample (25 ml) was heated with 1.2 mL of H2SO4, 0.5 mL of HNO3, 0.3 mL of 5% K2S2O8 solution and 0.3 mL of saturated K2Cr2O7 solution at 85-90°C for 2 h. The continuous-flow Hg-generation apparatus consisted of an autosampler, a peristaltic pump that propelled both the sample solution and the reducing reagent (4% SnCl2 solution in 10% HCl) at 3.9 ml/min, a gas-liquid separator that permitted the Hg vapor to be transferred to Ar carrier gas (20 ml/min), two moisture absorbers connected in series, and a six-port flow injection module that collected and transferred an portion of the gaseous Hg to a Au-wire absorber, which comprised a quartz tube (4 in. x 0.25 in. i.d.) wrapped with a Chromel wire heater and containing 0.5-1 g of Au wire (0.1-0.2 mm diameter). The Hg was desorbed by heating to ~500°C and carried to the spectrophotometer in an Ar stream (22 ml/min) for measurement at 253.7 nm. The calibration graph was linear up to 1 ng/ml and the detection limit was 2 pg/ml. The RSD (n = 10) for natural water containing 0.06 ng/ml of Hg was 3%. The procedure was applied to 11 water samples, and the results were confirmed by cold vapor AAS.
Mercury Environmental Fluorescence

"Direct Determination Of Ultratraces Of Thallium In Water By Flow Injection Differential Pulse Anodic-stripping Voltammetry"
Anal. Chim. Acta 1996 Volume 318, Issue 2 Pages 159-165
Zenon Lukaszewski*, Wlodzimierz Zembrzuski and Anna Piela

Abstract: Filtered water samples were diluted with 0.2 M ETDA (3:1) and 100 mL of the solution was continuously circulated at a flow rate of 15 ml/min through a voltammetric cell during the deposition period. The voltammetric cell was equipped with a Hg film working electrode on an epoxy resin impregnated graphite substrate (3.14 mm2), a SCE as the reference electrode and a Pt wire auxiliary electrode. The deposition was carried out at -900 mV for up to 120 min. At the end of the deposition period the flow was stopped and after 30 s the voltammogram was recorded by scanning the potential to ~e;-300 mV at 11.1 mV/s with a pulse amplitude of 50 mV. The calibration graph was linear from 25-100 pM-Tl with a 90 min deposition period and the detection limit was 10 pM. The RSD (n = 6-8) was 0.14% within the calibration range. The method was tolerant of a 1000-fold excess of Pb. The method was applied to the analysis of tap, river, lake and sea waters.
Thallium Environmental Water Lake River Sea Voltammetry

"Determination Of Ultratrace Amounts Of Cobalt By Catalysis Of The Tiron-hydrogen Peroxide Reaction With An Improved Continuous-flow Analysis System"
Talanta 1987 Volume 34, Issue 2 Pages 277-281
Kenji Isshiki, Eiichiro Nakayama

Abstract: A schematic diagram is given of the continuous-flow system in which air segmentation is introduced after mixing of the reactants, which were samples in 0.1 M HCl, 0.05 M Na2CO3 - NaHCO3 in 0.1 M NaOH, 0.01 M tiron and 5 mM H2O2. Optimum conditions were a reaction time of 210 s, a temperature of 30°C, pH 11.2, and absorbance measurement at 440 nm. From 3 to 5000 pg of Co(II) can be determined in 1 mL of acidified sample, at a rate of 40 samples h-1. The coefficient of variation (n = 10) were 1 and 3% for 100 and 10 pg mL-1 of Co, respectively. A considerable number of species interfere when present in 100-fold amounts relative to Co and must be removed before determination. Results are given for the determination of Co in seawater.
Cobalt Sea Spectrophotometry

"Electrothermal Atomic Absorption Spectrometric Determination Of Ultratrace Amounts Of Tin By In Situ Preconcentration In A Graphite Tube Using Flow Injection Hydride Generation With Online Ion-exchange Separation"
Talanta 1995 Volume 42, Issue 3 Pages 375-383
Guanhong Tao and Zhaolun Fang*

Abstract: Geological samples (0.5 g) were treated with 5 mL HNO3/HF (7:3) at 40°C. After boiling nearly to dryness a further 2 mL acid was added. After cooling, the digests were diluted to 50 mL and 1 mL was diluted further to 100 mL with 2 M HCl. Hair (0.2 g) or 1 mL serum was acid-treated as above and then the digests were diluted to 50 mL with 2 M HCl. Tap water samples were filtered and acidified to 2 M HCl with concentrated HCl. The samples were passed through a microcolumn (3 cm x 3 mm i.d.) packed with anion-exchanger D-201 (Shenyang Organic Chemicals Co.). The Sn was retained as its chlorostannate complex and subsequently eluted with water into the hydride generation system. The hydride and H2 evolved were separated from the liquid phase in a gas-liquid separator and transferred into a Pd-coated graphite tube pre-heated to 300°C to collect the analyte which was later atomized at 2300°C, followed by AAS. Tin was determined at a sampling frequency of 30/hr with a detection limit of 0.01 µg/l. RSD were ~1.5%.
Tin Blood Serum Hair Geological Water Sample preparation Spectrophotometry

"Determination Of Ultratrace Amounts Of Arsenic(III) By Flow Injection Hydride Generation Atomic Absorption Spectrometry With Online Preconcentration By Coprecipitation With Lanthanum Hydroxide Or Hafnium Hydroxide"
Talanta 1996 Volume 43, Issue 6 Pages 867-880
Steffen Nielsena, Jens J. Slotha and Elo H. Hansen

Abstract: Sample stream (4 ml/min) was merged with a stream of coprecipitation agent (0.6 ml/min) of La(III) or Hf(IV) for 100 s and passed through a 6 cm mixing coil. The resulting stream merged with a buffer stream (0.6 ml/min) of 0.3 M ammonium chloride and through a knotted reactor (200 cm). The precipitate was collected on the walls of the reactor and the effluent was discarded. After precipitation, the coprecipitation and buffer stream flows were stopped and a stream of HCl (8.7 ml/min) was passed through the reactor to dissolve the precipitate. The analyte plug passed to a hydride generating system where it merged with a stream of sodium tetrahydroborate (1.5 ml/min), through a reaction coil (60 cm) to a gas-liquid separator. The arsine and evolved H2 were swept to the atomizer cell by Ar carrier gas and the absorption was measured by AAS. La(III) was more effective for collecting As(III) than Hf(IV). The detection limit was 0.003 µg/l of As(III) with a RSD (n = 11) of 1% at 0.1 µg/l.
Arsenic Spectrophotometry

"Catalytic Determination Of Manganese At Ultratrace Levels By Flow Injection Analysis"
Analyst 1986 Volume 111, Issue 1 Pages 69-72
S. Maspoch, M. Blanco and V. Cerdá

Abstract: The catalytic effect of Mn(II) on the oxidation of succinimide dioxime in alkaline medium was used for determination of Mn(II) by flow injection analysis with photometric detection at 695 nm. Variation of the reaction temperature between 25°C and 45°C allows the determination range to be extended from 0.2 to 1300 ng mL-1, with a sampling frequency of 45 h-1 and a coefficient of variation of 1.3 to 1.0%. Injection of the sample in a flow of EDTA solution overcomes most interference. Interference by Co(II), Fe(II) and Mg(II) was investigated. The method was used to determine Mn in reagent-grade ZnO and HClO4 and in powdered coffee and rice.
Manganese(II) Rice Powder Inorganic compound Inorganic compound Spectrophotometry

"Determination Of Ultratrace Amounts Of Selenium(IV) By Flow Injection Hydride-generation Atomic Absorption Spectrometry With Online Preconcentration By Coprecipitation With Lanthanum Hydroxide"
Analyst 1994 Volume 119, Issue 2 Pages 333-337
Guanhong Tao and Elo H. Hansen

Abstract: Water was filtered, acidified with concentrated HCl (10 ml/l) and boiled for 5 min. After cooling, NaOH was added to pH 3 and 0.5% lanthanum nitrate was added to a concentration of 20 mg/l. The resulting solution was mixed in a flow manifold (4 ml/min) with 0.2 M ammoniacal buffer solution of pH 9.1 (1.5 ml/min) and the precipitate formed was collected on the inner walls of a knotted reactor. After 100 s, the flow manifold configuration was changed so that the analyte was eluted from the reactor walls with 1 M HCl (9 ml/min). The eluate was merged with 0.3% NaBH4 in 0.05 M NaOH (1.5 ml/min) and the resulting stream was passed through a reaction coil (20 cm) and a gas-liquid separator, where H2Se was generated. The hydride, together with evolved H2 was swept into the atomizer and absorption was measured at 196.1 nm. The elution sequence lasted 10 s. Calibration graphs were linear from 0.01-0.5 µg/l of Se, with a detection limit of 0.001 µg/l. RSD for the determination of 0.5 and 0.1 µg/l of Se were 0.7% and 3.0%, respectively. Effects of co-existing ions were studied. The method was applied to natural and potable waters.
Selenium Environmental Water Spectrophotometry

"Adsorption-concentration Of Ion Associate Formed Between Molybdosilicate And Malachite Green On A Miniature Filter: Its Application To Trace And Ultratrace Determination Of Silicon"
Analyst 1995 Volume 120, Issue 10 Pages 2605-2611
Joko P. Susanto, Mitsuko Oshima and Shoji Motomizu

Abstract: A spectrophotometric method for Si determination (as silicate), based on an adsorption-concentration procedure, is described. Portions (30 ml) of standard silicate solution were mixed with 0.5 mL 1.7 M H2SO4 and 0.5 mL 0.52 M molybdate and the solution was left for 20 min. A 1 mL portion of 0.34 mM Malachite Green in 6.1 M H2SO4 was added and the mixture was left to stand for 35 min. The solution was filtered through a cellulose nitrate membrane filter (5 mm diameter; pore size 1 µm) under suction. The ion associate and the membrane filter were then dissolved in 1 mL methyl Cellosolve and the absorbance of the resulting solution was measured at 627 nm by using a previously described flow injection system (Susanto et al., Ibid., 1995, 120, 187). The calibration graph was linear up to 9 ng/ml of Si and the detection limit was 0.5 nM. The RSD (n = 6) was 4.3%. The method was applied to the analysis of Si in purified water.
Silicon Water Spectrophotometry

"Determination Of Ultratrace Amounts Of Selenium(IV) By Flow Injection Hydride Generation Atomic Absorption Spectrometry With Online Preconcentration By Coprecipitation With Lanthanum Hydroxide. 2. Online Addition Of Coprecipitating Agent"
Analyst 1996 Volume 121, Issue 1 Pages 31-35
Steffen Nielsen, Jens J. Sloth and Elo H. Hansen

Abstract: The sample stream (6.4 ml/min) was mixed with a stream (0.4 ml/min) of 210 mg/l lanthanum nitrate (total sample volume aspirated: 10.6 ml) and passed through a 6 cm mixing coil before merging with a stream (0.4 ml/min) of 0.2 M NH4Cl buffer of pH 9.15 at the entrance to a 100 cm knotted Microline reactor. The precipitate that formed was collected on the inner walls of the knotted reactor. A stream (9 ml/min) of HCl was then passed through the knotted reactor to dissolve the collected precipitate. The concentrated zone was merged with a stream (1.5 ml/min) of 0.3% NaBH4 in 0.05 M NaOH and the hydrogen selenide produced was subsequently determined by AAS at 196.1 nm. The calibration graph was linear for 0.01-0.3 µg/l Se(IV), the detection limit was 0.005 µg/l and the RSD (n = 11) was 0.5%. The throughput was 33 samples/h. An enrichment factor of 40 was achieved.
Selenium(IV) Spectrophotometry

"Determination Of Ultratrace Amounts Of Antimony(III) In Water By Flow Injection Online Sorption Preconcentration In A Knotted Reactor Coupled With Electrothermal Atomic Absorption Spectrometry"
Analyst 1996 Volume 121, Issue 8 Pages 1061-1067
Xiu-Ping Yan, Willy Van Mol and Freddy Adams

Abstract: The sample was acidified to be 0-1 M in HCl and was merged at a flow rate of 5.4 ml/min with a reagent stream of 0.02% ammonium pyrrolidine dithiocarbomate (APDC) at 1.4 ml/min. The resulting chelate was concentrated on to the inner walls of PTFE knotted reactor (100 cm x 0.5 mm i.d.); the pre-concentration took 30 s. The adsorbed chelate was washed with a stream of 0.02% APDC/0.02% HNO3 at a flow rate of 3 mL/min. The residual solution was removed by an air stream then the chelate was eluted from the knotted reactor with 35 µL ethanol delivered by a stream of air at a flow rate of 3 mL/min. The eluate was analyzed for Sb(III) by ETAAS using drying, pyrolysis and atomization temperatures of 90, 800 and 2000°C, respectively (other experimental conditions tabulated); detection was at 217.6 nm. The calibration graph was linear from 0.1-2 µg/L Sb(III); the detection limit was 0.021 µg/L. RSD (n = 11) was 2.9%. The throughput was 42 samples/h. The method was applied to seawater. Recoveries of Sb(III) were quantitative.
Antimony Sea Spectrophotometry

"Determination Of Ultra-trace Levels Of Metal Ions In Seawater With Online Preconcentration And Electrothermal Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1991 Volume 6, Issue 2 Pages 119-122
V. Porta, O. Abollino, E. Mentasti and C. Sarzanini

Abstract: An on-line pre-concentration system for electrothermal atomic absorption spectrometry was developed. A miniature silica C18 column was inserted at the tip of the autosampler arm. A modification of the tubing line of the autosampler allowed either the flow of the sample through the column or the operation of the autosampler in the normal mode. The retention of the metal ions in the form of complexes on the microcolumn was achieved by using pyrrolidin-l-yl dithioformate as the complexing agent; acetonitrile was then used for the elution. The direct injection of the eluate into the graphite furnace gave high pre-concentration factors, ranging between 20 and 225, which are sufficient for the determination of Cd, Pb, Cu, Ni, Co and Fe in Antarctic sea-water. The blank level was very low and the detection limits ranged from 0.4 ng l-1(Cd) to 25 ng l-1(Fe).
Metals, heavy Sea Spectrophotometry

"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.
Cadmium Copper Lead Nickel Environmental Spectrophotometry Sample preparation

"Optimization And Use Of Flow Injection Vapor-generation Inductively Coupled Plasma Mass Spectrometry For The Determination Of Arsenic, Antimony And Mercury In Water And Seawater At Ultra-trace Levels"
J. Anal. At. Spectrom. 1993 Volume 8, Issue 1 Pages 35-40
Andreas Stroh and Uwe Völlkopf

Abstract: An Elan 5000 ICP mass spectrometer and a FIAS-200 equipped with an AS-90 autosampler for online flow injection vapor generation (all from Perkin-Elmer) were used with Ar as plasma and purge gas for the cited analyzes; the optimized operating conditions are specified. The sample solution was injected into 3% HNO3 as carrier rather than HCl (to avoid formation of ArCl, which could interfere with the 75As signal) and the resulting stream was mixed with 0.2% NaBH4 solution The hydrides were entrained in Ar and, after passage through a gas - liquid separator, introduced into the plasma. Bismuth was used as internal standard. Detection limits ranged from 0.5 ng L-1 for Bi to 16 ng L-1 for 78Se; pre-reduction with KI improved the detection limits for As and Sb to 6 and 1.3 ng l-1, but impaired that for Hg. The coefficient of variation (n = 5) ranged from 0.5 to 1.6%. Results obtained for four reference water samples agreed with the certified values.
Arsenic Antimony Mercury Sea Mass spectrometry

"Determination Of Trace And Ultratrace Amounts Of Germanium In Environmental Samples By Preconcentration In A Graphite Furnace Using A Flow Injection Hydride-generation Technique"
J. Anal. At. Spectrom. 1993 Volume 8, Issue 4 Pages 577-584
Guanhong Tao and Zhaolun Fang

Abstract: Trace and ultratrace levels of Ge were determined using flow injection (FI) hydride-generation followed by trapping and electrothermal atomization. Samples of garlic, tap water, ginseng and geochemical reference materials were pre-treated (details given) and diluted with 0.15 M or 3 M HCl then propelled into the FI system and merged with a tetrahydroborate reductant. This generated hydrides together with some H, which were separated in a gas - liquid separator, transferred to a Pd-coated graphite furnace pre-heated to 400°C and atomized by heating to 2500°C. Sensitivities and interference effects using different concentration. of HCl were compared. The use of high acidities and FI rather than batch collection led to reduced interference. Interference studies of 13 metals were performed (results given). Calibration graphs were rectilinear up to 0.5 µg L-1 of Ge for use of 0.15 M HCl and up to 2.5 µg L-1 for use of 3 M HCl with detection limits of 0.004 and 0.03 µg l-1, respectively, using 4.5 mL of sample. Coefficients of variation (n = 11) were 2.0% at 0.3 µg L-1 of Ge in 0.15 M HCl and 2.5% at 1.5 µg L-1 in 3 M HCl.
Germanium Water Vegetable Vegetable Geological Spectrophotometry

"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.
Cadmium Water Fluorescence Spectrophotometry

"Determination Of Technetium-99, Thorium-230 And Uranium-234 In Soils By Inductively Coupled Plasma Mass Spectrometry Using Flow Injection Preconcentration"
J. Anal. At. Spectrom. 1994 Volume 9, Issue 9 Pages 927-933
Mark Hollenbach, James Grohs, Stephen Mamich, Marilyn Kroft and Eric R. Denoyer

Abstract: A new method is described for the determination of 99Tc, 230Th, and 234U at ultratrace levels in soils. The method used flow injection (FI) for online pre-concentration of 99Tc, 230Th and 234U before detection using inductively coupled plasma mass spectrometry (ICP-MS). The FI-ICP-MS method results in greater sensitivity and freedom from interferences compared with direct aspiration into an ICP mass spectrometer. Detection limits are improved by approximately a factor of 10. The FI-ICP-MS method is also faster, less labour intensive and generates less laboratory waste than traditional radiochemical methods. The accuracy of the method was tested for 99Tc by comparison to liquid scintillation limits in the soil for 99Tc, 230Th and 234U were 11 mBq/g, (0.02 ng/g), 3.7 mBq/g (0.005 ng/g) and 0.74 mBq/g (0.003 ng/g), respectively. Sample preparation, analysis protocol, and method validation are described.
Technetium-99 Thorium-230 Uranium-234 Environmental Mass spectrometry Sample preparation

"Determination Of Ultratrace Amounts Of Cobalt In Ocean Water By Laser-excited Atomic Fluorescence Spectrometry In A Graphite Electrothermal Atomizer With Semi Online Flow Injection Preconcentration"
J. Anal. At. Spectrom. 1994 Volume 9, Issue 11 Pages 1195-1202
Alexander I. Yuzefovsky, Robert F. Lonardo, Mohui Wang and Robert G. Michel

Abstract: A flow injection, semi online, microcolumn pre-concentration system consisting of C18 functional groups (schematic given) was used as described previously (cf. Microchem. J., 1993, 48, 326). The microcolumn was integrated with laser-excited AFS in an electrothermal atomizer. Two ocean water reference materials, viz., CASS-2 and NASS-4, NASS-4 and CASS-2 were mixed with sodium diethyldithiocarbamate in pH 9 buffer to pH 2.5 and 2.4, respectively. The solutions were pumped directly onto the column at 0.15 ml/min. Sub-boiled water was passed through the column at the same flow rate and in the same direction. Ethanol was then passed through at the same flow rate but in the reverse direction. The ethanol eluate containing Co was then collected and delivered directly onto the L'vov platform. A 40 µL portion was analyzed. The detection limit based on a 12.5-fold pre-concentration was 1 ng/l of Co. RSD were 9 and 13% for CASS-2 and NASS-4, respectively.
Cobalt Sea Spectrophotometry Fluorescence

"Determination Of Antimony By Continuous Hydride Generation Coupled With Nondispersive Atomic Fluorescence Detection"
J. Anal. At. Spectrom. 1995 Volume 10, Issue 11 Pages 969-974
Alessandro D'ulivo, Leonardo Lampugnani, Giovanna Pellegrini and Roberto Zamboni

Abstract: A sensitive method for the determination of Sb at ultratrace levels was developed by coupling continuous hydride generation with non-dispersive atomic fluorescence detection. A miniature argon-hydrogen diffusion flame was employed as the atomizer and a commercially available electrodeless discharge lamp as the light source, One of the main problems was the scattering signal generated by small droplets of solution which markedly deteriorated the signal-to-noise ratio. A simple way to remove the scattering signal was to operate under mild reaction conditions in order to minimize droplet formation. Under the optimized conditions, a limit of detection of 22 pg cm(-3) of Sb (3s of the blank) was achieved, with a precision of 1.2% at the 5 ng cm(-3) level and the calibration graphs were linear over more than 4 decades of concentration, L-Cysteine was employed both in the pre-reduction step and in the control of the interference effects arising from concomitant elements and acid mixtures, The analytical procedure was applied to the determination of Sb in certified reference materials of sediments, metallic copper and riverine water. (29 References)
Antimony Environmental Metal River Fluorescence

"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. Fernández Sánchez 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.
Cadmium Spectrophotometry

"Flow Injection Of Ultra Trace Level Samples Into Laser-based Detectors"
Anal. Chem. 1982 Volume 54, Issue 13 Pages 2337-2340
J. M. Harris

Abstract: Application of lasers to the detection of ultratrace level species is presently hindered by traditional methods of sample manipulation. Flow Injection analysis (FIA) developed originally to automate routine determinations appears to have several attributes which would be beneficial In presenting samples to laser detectors. These attributes include small volume sampling, low risk of contamination, and large dynamic range for a given expenditure of time and reagents. Laser-induced fluorescence is used in this work to assess the merits of flaw injection for handling ultratrace level samples. The trade-off between sample throughput and dynamic range Is investigated, and the results are treated by using the theory of sample dispersion.
Fluorescence

"Solid-surface Room-temperature Phosphorescence Optosensing In Continuous-flow Systems: An Approach For Ultratrace Metal Ion Determination"
Anal. Chem. 1991 Volume 63, Issue 17 Pages 1759-1763
Rosario Pereiro Garcia, Yi Ming Liu, Marta Elena Diaz Garcia, and Alfredo Sanz-Medel

Abstract: Solid-surface room-temperature phosphorescence (SSRTP) optosensing in an aqueous flow is reported here for the first time, and it has been applied to aluminum control in samples of clinical interest. This technique makes use of flow injection analysis (FIA) and is based on the transient immobilization (on a strongly basic anion-exchanger resin packed in a flow cell) of the complex formed by the phosphorogenic reagent 8-hydroxy-7-iodo-5-quinolinesulfonic acid (ferron) with aluminum in a continuous-flow carrier at pH 5.5. The analytical performance characteristics of the proposed method for semiautomated analysis and control of very low levels of Al were as follows: 2 µg/L detection limit, +- 3.2% precision analyzing 40 µg/L of the metal and most of the common ions in biological samples did not interfere. Only Fe(III) caused serious interference, but it can be masked by 1,10-phenanthroline. The recommended method has been successfully tested for Al determinations at µg/L levels in samples of particular importance today (dialysis fluids and concentrates). Basic experiments on the characteristics of the RTP observed for different media used to secure the necessary rigidity (micelles, vesicles, filter paper, strong anionic resins, etc.) have demonstrated that Dowex 1 times 2-100 resin seems to provides the best sheltering to the excited triplet state. Possible interaction mechanisms between phosphor and supports are suggested. The cited technique was applied in the determination of Al in clinical samples. Sample or standard solution (0.5 ml) were injected into 0.2 M acetic acid - Na acetate buffer solution (pH 5.5) in the flow injection manifold (described with diagram) and mixed in a T-piece with a buffer stream into which 75 µM-8-hydroxy-7-iodoquinoline-5-sulfonic acid solution (0.6 ml) had been injected. The resulting stream was passed through a 3.5-m reaction coil and then to a flow cell (25 µL) containing Dowex IX2-100 resin. The phosphorescence of the complex adsorbed on the resin was measured at 600 nm (excitation at 400 nm). After detection, the adsorbed complex was desorbed with 6 M HCl (2 ml). Calibration graphs were rectilinear up to 100 ng mL-1 of Al. The detection limit was 2 ng mL-1 of Al. The coefficient of variation was ±3.2% at 40 ng mL-1 of Al
Aluminum Biological Phosphorescence

"Nitroprusside And Methylene Blue Methods For Silicone Membrane-differentiated Flow Injection Determination Of Sulfide In Water And Waste Water"
Anal. Chem. 1992 Volume 64, Issue 1 Pages 36-43
Vlastimil Kuban, Purnendu K. Dasgupta, and John N. Marx

Abstract: A membrane gas permeation module using a silicone rubber tube (0.6 mm x 12 cm; Patto Products) was incorporated into a flow injection system (described). Hydrogen sulfide evolved from the acidified sample of water or waste water was pre-concentrated by permeation in a stationary alkali acceptor solution, before being subjected to either the nitroprusside or the methylene blue method to determine the sulfide present. The methylene blue method is ~30x more sensitive, and allows determinations at sub µg L-1 levels. The detection limit for the nitroprusside method was 2 µg L-1 for 12 mL samples pre-concentrated in the membrane system. The membrane is highly resistant to fouling and analysis of untreated waste water samples containing suspended solids, oil and grease is possible. Since the nitroprusside method uses less aggressive reagents than the methylene blue method, its use is recommended unless ultratrace determinations are essential. H2S evolved from an acidified sample is pre-concentrated by permeation in a stationary alkaline acceptor solution enclosed in a silicone rubber sample loop. Depending on the sample volume pre-concentrated, the applicable analysis range spans low µg/L to tens of mg/L for both methods. The methylene blue method is more sensitive by a factor of ~30 and actually permits practical determinations in the sub µg/L levels. The limit of detection (LOD) for the nitroprusside method is 20 µg/L for a 20 µL sample by conventional flow injection determination (no membrane, throughput 30 samples/h) and <2 µg/L for a 12 mL sample pre-concentrated in the membrane system (throughput 5 samples/h). The membrane is highly resistant to fouling and permits anal. of untreated wastewater samples bearing suspended solids, oil, grease, etc., without any pretreatment. No significant interference is observed with either chemical Although the nitroprusside chemical is less sensitive, it does not involve the use of concentrated aggressive reagents and is recommended unless ultratrace determinations are essential. Viable reaction mechanisms are proposed for both of these chemistries.
Sulfide Waste Environmental Spectrophotometry

"Development Of Analytical Methods For The Determination Of Ions And Acidity In Individual Raindrops"
Fresenius J. Anal. Chem. 1991 Volume 340, Issue 9 Pages 548-552
K. B&auml;chmann, I. Haag, U. Sprenger, K.-H. Steeg, K. Steigerwald, B. Bastian and A. R&ouml;der

Abstract: Raindrops are frozen in liquid N and separated by size fractionation with use of mesh sieves. Several analytical procedures are also described for the determination of ions at ultratrace levels and with volume 1 µL; free and total acidity of the drops are determined by the reaction with suitable acid/base indicators in a flow-injected system with gradient mixing and UV - visible spectrophotometric detection. Alkaline- and alkaline-earth-metals are determined on microbore cation-exchange columns of ION-210 metals and Fast Cation 1 with Ce as mobile phase. Formate, Cl-, NO3- and SO42- anions are separated on a column of PRP X-100 with 3 mM Na2CO3 buffer - 6% acetonitrile - 0.17 mM p-cyanophenol as mobile phase and with conductivity detection. Acetate, formate, pyruvate and methane sulfonate are separated on a column of HPIC AS5A with Na2B4O7 as mobile phase. Iron, Pb and Mn are determined from size fractions by graphite-furnace AAS. Detection limits are given.
Acidity Rain Spectrophotometry Spectrophotometry

"Analysis Of Solid Samples By ICP-mass Spectrometry"
Fresenius J. Anal. Chem. 1992 Volume 342, Issue 12 Pages 917-923
Uwe Voellkopf, M. Paul and E. R. Denoyer

Abstract: ICP-mass spectrometry is typically used as a technique for very rapid multielement analysis at trace and ultratrace levels of solutions by continuous sample aspiration and nebulization. However, ICP-MS is well suited to be used as a detector for other sample introduction devices. For the analysis of solid samples laser sampling and electrothermal vaporization accessories may be used as sample introduction devices for ICP-MS. Laser sampling permits the analysis of many different types of solid materials. For solid sampling ETV-ICP-MS analysis it is of advantage to reduce the sample to a fine powder prior to analysis. For automated analysis powders may be introduced as slurries into the graphite furnace by means of a slurry sampling device. Since appropriate certified solid reference materials are not always available for calibration, or since they are not certified for all analyte elements of interest, the analyzes discussed in this contribution were performed semi-quantitatively. The instrument response function was established using reference materials which were similar in their composition to the samples. The results of semi-quantitative bulk analyzes of glass (NIST 612) and geological material (USGS GXR-3) by laser sampling ICP-MS are in good agreement with the certified values. The concentrations. of the analytes determined in the glass sample were in the range of 10 µg/g to 80 µg/g. The lowest analyte concentration in the geological sample was 0.4 µg/g (Eu) and the highest was approximately 186 mg/g (Fe). The precision achieved was in the order of 5% to 15%. Laser sampling ICP-MS is not only suitable to bulk analysis but also to analyzes where spatial information is required. As an example for such an application the determination of Pb in a wine bottle cork stopper is discussed. The slurry sampling technique was used for the semi-quantitative analysis of NIST coal reference samples by electrothermal vaporization ICP-MS. The accuracy achieved with this approach was within a factor of ±2 of the reference values.
Iron Europium Lead NIST 612 USGS GXR-3 Geological Commercial product Mass spectrometry

"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.
Cadmium Cobalt Copper Lead Nickel Sea Water Spectrophotometry Sample preparation

"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%.
Copper Cadmium Sea Spectrophotometry

"Hyphenated Techniques Combined With Atomic Spectrometry For Environmental Studies"
Microchem. J. 1995 Volume 51, Issue 1-2 Pages 88-98
Wang X. O., Zhuang Z. X., Yang P. Y. and Huang B. L.

Abstract: The development and application of hyphenated techniques combined with atomic spectrometries for environmental analysis at Xiamen University, China, are described. The techniques include: flow injection online microcolumns combined with AAS, GFAAS, ICP AFS and ICP-AES for trace and ultratrace analysis of water; flow injection online solvent extraction combined with AAS and ICP-AES; flow injection online hydride generation for the elemental analysis of Chinese herbs and rain by AAS and ICP-AES; flow injection online coprecipitation-dissolution for the determination of trace heavy metals in seawater and rain by GFAAS and ICP-AES; and HPLC combined with ICP-AES for multielement speciation analysis of Chinese tea.
Metals, trace Metals, heavy Plant Plant Rain Sea HPLC Fluorescence Spectrophotometry Spectrophotometry Spectrophotometry Spectrophotometry Spectrophotometry Sample preparation

"New Developments In Flow Injection Vapor Generation Atomic Absorption Spectrometry"
Microchem. J. 1996 Volume 53, Issue 1 Pages 42-53
Fang Zhaolun a, Tao Guanhonga, Xu Shukuna, Liu Xuezhua and Wang Jingb

Abstract: A review is presented of the enhancements in sensitivity and selectivity brought about by new developments in flow injection techniques for combined FI-vapor generation AAS. In particular, selectivity enhancements by (i) optimization of FI parameters and reaction conditions, (ii) online separation of interferents and (iii) online sample matrix modification as well as sensitivity enhancements by (i) reagent addition, (ii) online coprecipitation pre-concentration and (iii) in situ pre-concentration of hydrides in a graphite furnace are discussed in detail. The enhancements are illustrated by applications in the trace or ultratrace determination of Ge, Se, As, Sb, Bi, Sn and Pb in environmental materials and Chinese herbal medicines. (28 references).
Trace elements Environmental Pharmaceutical Spectrophotometry

"Optimization Of Flow Injection Online Microcolumn Preconcentration Of Ultratrace Elements In Environmental Samples Prior To Their Spectrochemical Determination"
Microchem. J. 1996 Volume 54, Issue 4 Pages 391-401
Zs. Horv&aacute;th, A. L&aacute;sztity, K. Zih-Per&eacute;nyi and &Aacute;. L&eacute;vai

Abstract: Multi-element pre-concentration of elements in water was performed by online flow injection on an iminodiacetic acid/ethyl cellulose (IDAEC) microcolumn. The eluent was 2 M HNO3 (2.5 ml/min). The pre-concentration of the elements was modelled in the presence of complexing agents such as citrate and oxalate at high Ca, Mg and sulfate concentrations. Elements were determined by ICP-MS or AAS. The effect of the species present in the solution was studied after construction of the species distribution curves using critical, estimated and measured stability constants. The stability constants of the IDAEC chelates were determined potentiometrically, and the constants were estimated using computer programs.
Trace elements Environmental Environmental Mass spectrometry

"Micellar Enhanced Chemiluminescence Of 1,10-phenanthroline For The Determination Of Ultratraces Of Copper(II) By Flow Injection Method"
Anal. Lett. 1984 Volume 17, Issue 4 Pages 251-263
Masaaki Yamada; Shigetaka Suzuki

Abstract: Equal volume of 0.06 mM 1,10-phenanthroline, aqueous 5% H2O2, 0.1 M NaOH and 0.01 M ethylhexadecyldimethylammonium bromide were blended, and 20 µL of solution containing 15 pg mL-1 of Cu(II) was injected; the chemiluminescence produced was measured at 445 to 450 nm. A 2-m mixing coil was used. The detection limit (signal-to-noise ratio 3:1) was 0.3 pg of Cu(II). Interference tests were carried out with eleven surfactants and nine metal species; a 0.01 M solution of Pb(II) gave a signal 25% of that from 10 nM-Cu(II)
Copper(II) Chemiluminescence

"Ultratrace Determination Of Phosphate Ion Based On Filtration-dissolution And Flow-through Spectrophotometric Measurement"
Anal. Sci. 1995 Volume 11, Issue 1 Pages 155-160
S. MOTOMIZU, J. P. SUSANTO, M. OSHIMA, H. MIKASA and Y. HORI

Abstract: A 10^-40 mL portion of standard 3 mM phosphate solution was treated with 1 mL mixed reagent solution (containing 60 µM-Malachite Green, 0.12 M molybdate and 2.75 M HCl) for 5 mL phosphate standard solution. The mixture was left for 5 min and was filtered, under suction through a membrane filter. The filter was washed with 10 mL water, the filter and its contents were dissolved in 1 mL Methyl Cellosolve and the absorbance of the solution was measured at 627 nm by the flow injection technique (details given). The calibration graph was linear from 18 pg/ml to 1 ng/ml of P in 40 mL sample and the detection limit was 3 pg/ml. As(V) severely interfered with the determination. The method was applied to the determination of phosphate in purified water.
Phosphate Water Spectrophotometry

"Tandem Online Separations: An Alternative Sample Presentation In Atomic Spectrometry For Ultra-trace Analysis"
Acta Chim. Hung. 1991 Volume 128, Issue 4-5 Pages 551-558
Sanz Medel, A.;Menendez Garcia, A.;Fernandez, M.L.;Sanchez Uria, J.E.

Abstract: The coupling of continuous-separation - pre-concentration. devices with atomic spectrometers for ultra-trace elementary analysis is discussed. Simple systems are first outlined, including solid - liquid and liquid - liquid online flow injection extraction coupled with AAS or ICP-AES for Al determination in biological fluids, and continuous gas - liquid separation coupled with ICP-AES for As determination in steel and as an introduction device for S2- determination in a microwave plasma. Examples are then given of tandem configurations in which two different continuous separation units are combined in a single online configuration. A tandem online device based on continuous extraction combined with hydride generation and coupled with ICP-AES for direct As, Sb and I- determinations is described, as well as a continuous liquid - liquid extraction device coupled with ICP-AES or AAS for indirect I- determination. Results show that many sensitivity and selectivity limitations of ultra-trace analysis can be overcome by the use of tandem online separation techniques.
Aluminum Arsenic Alloy Biological fluid Spectrophotometry Spectrophotometry Sample preparation

"Determination Of Ultratraces Of Cyanide Ion By Flow Injection Analysis With Surfactant Bilayer Vesicle-catalyzed And Uranine Sensitized Chemiluminescence"
Bunseki Kagaku 1986 Volume 35, Issue 12 Pages 955-960
Ishii, M.;Yamada, M.;Suzuki, S.

Abstract: Cyanide was determined in a flow injection system in which the sample was injected into a flow of 0.05 M NaOH - 7.5 mM didodecyldimethylammonium bromide and a 1 mM solution of uranin (C. I. Acid Yellow 73) was added subsequently. Measurement of the chemiluminescence produced provided a limit of detection of 2 nM for a 20 µL sample injection or 0.3 nM in a continuous sample flow, with a rectilinear range of two orders of magnitude, a coefficient of variation of 2.1% for 0.05 ng of CN- (n = 10) and a sampling rate of up to 360 h-1. The method was applied to determination of CN- in river water.
Cyanide River Chemiluminescence

"Sensitive Determination Of Hydrogen Peroxide By FIA Using An Enhanced Luminol Chemiluminescence System With A Mixed Dye-sensitizer"
Bunseki Kagaku 1992 Volume 41, Issue 3 Pages 125-133
Ishii, M.;Shirai, M.

Abstract: The method is based on the enhancement of the chemiluminescence of the luminol - H2O2 system that occurs in the presence of eosin Y (C.I. Acid Red 87) and uranin (C.I. Acid Yellow 73). The luminol - NaOH - eosin Y - uranin solution is injected into the aqueous carrier stream (8 mL min-1) from a 0.1 mL sample injector mounted 50 cm from the detector, and the sample solution is injected from a 20 µL injector mounted 20 cm from the detector. The detection limit was 10 pM-H2O2, and the coefficient of variation (n = 10) at 10 nM-H2O was 1.7%. Weak interference was caused by µM concentration. of heavy-metal ions. The method was used to determine H2O2 in tap water; recoveries were almost quantitative. A mixed dye-sensitizer (eosin Y/uranine) was applied to H2O2 determination at ultratrace levels using luminol chemiluminescence system. The proposed single line FIA system was equipped with 2 sample injectors (Rheodyne, 7125 type) placed on the flow line at a distance of 30 cm from each other; the large one (100 µL) at a distance of 10 cm from the pump was employed for the CL reagent solution and the small one (20 µL) at a distance of 20 cm to the detector for the H2O2 solution (sample). The lower detection limit: 1 x 10^-11 M in 20 µL injection volume, relative standard deviation: 1.7% in 10 repeated runs involving a 20 µL injection of the 1 x 10^-8 M H2O2 solution, anal. time: ~5 s.
Hydrogen peroxide Water Chemiluminescence

"Plasma Spectrometry In The Earth Sciences: Techniques, Applications, And Future Trends"
Chem. Geol. 1992 Volume 95, Issue 1-2 Pages 1-33
Ian Jarvis and Kym E. Jarvis

Abstract: A review with many references. Plasma spectrometry is one of the most popular and versatile techniques for the analysis of geological and environmental samples, including rocks and minerals, waters, dust, vegetation, soils, sewage sludges and sediments. Inductively coupled or DC argon plasmas are used as emission sources in ICP- and DCP-atomic emission spectrometry (ICP-AES, DCP-AES); an ICP provides an ion source in ICP-mass spectrometry (ICP-MS). Reviews of the two plasma sources sample introduction systems, and the instrumental and analytical performances of emission and mass spectrometers, demonstrates the superiority of higher-temperature, ICP-based systems. ICP-AES and ICP-MS are characterized by wide linear responses of more than five orders of magnitude. They are rapid and highly cost-effective multi-element techniques which can theoretical determine over 70 elements in <2 mL of sample solution in less than 2 min. In practice such performance is rarely possible because detection limits, and particularly in the case of ICP-AES, spectral interferences, limit the range of elements which may be quantified. Plasma spectrometry is primarily a solution-based technique, and the dissolution step ultimately controls both the range of elements quantifiable and the limits of determination which may be achieved. Limits of quantitative analysis for solid samples are typically in the order of a few µg g-1 for ICP-AES and a few hundred ng g-1 for ICP-MS. However, chemical separation and pre-concentration procedures are described for the rare-earth elements, precious metals and several other elemental groups, which enable determinations to be made at sub ng g-1 levels. The better precision of ICP-AES and the greater sensitivity, near-complete freedom from interferences, and isotopic capabilities of ICP-MS, mean that ICP-AES is best used for major- and minor-element determinations, while ICP-MS is reserved for trace- and ultratrace-element work. Comparisons with atomic absorption x-ray fluorescence and instrumental neutron activation demonstrate that plasma-based techniques compete well with more established instrumental methods. Further developments in sample preparation and presentation procedures, particularly in the area of solid sample analysis, will increase further the potential applications of plasma spectrometry in the earth sciences.
Metals, precious Metals, rare earth Mass spectrometry Spectrophotometry Spectrophotometry

"Comparison Of The Limits Of Detection Obtained By Means Of A H.f. Plasma (ICP) Used As A Source Of Photons Or Ions In Elementary Analysis"
Chimia 1990 Volume 44, Issue 4 Pages 93-96
Poussel, Emmanuelle; Michel Mermet, Jean

Abstract: A discussion is presented of the fundamental principles, including instrumental design, which determine the limits of detection in ICP-AES and ICP-MS. The better sensitivity of ICP-MS for analysis of solution is less of an advantage in analysis of solids because of the greater dilution factor that may be required. Alternative methods of sample introduction, including flow injection, electrothermal vaporization and laser ablation, are considered. These developments and those in instrumental design will make ICP-MS a very powerful method for ultratrace analysis.
Spectrophotometry Mass spectrometry

"Determination Of Ultratrace Amounts Of Selenium(IV) In Water And Soil Extracts By Flow Injection Online Ion-exchange Preconcentration Hydride Generation Atomic Absorption Spectrometry"
Kexue Tongbao 1990 Volume 35, Issue 6 Pages 526-527
XU SHU-KUN, ZHANG SU-CHUN, FANG ZHAO-LUN

Abstract: Sample solution (9 mL min-1) was merged with 0.2 M acetate buffer (pH 5; 0.5 mL min-1) before passing through a column (4.5 cm x 3 mm) of D201 macroporous anion exchanger (50 mesh). Selenium was eluted with 1 M HCl (6 mL min-1) and the eluate was mixed with 0.5% of NaBH4 in 0.1% NaOH solution (2 mL min-1). The SeH4 was separated in a gas - liquid separator and carried by Ar (150 mL min-1) to a silica atomizer heated at 700°C for determination by AAS at 196.0 nm. The detection limit was 2 ng l-1, and the sampling rate was 50 h-1. The coefficient of variation were 1.1% (n = 11) for 0.5 µg L-1 and 6.4% (n = 10) for 0.01 µg l-1. Recoveries from tap, well and mineral waters were 96 to 100% and from soil extracts were 92 to 102%.
Selenium(IV) Environmental Mineral Well Water Ion exchange Spectrophotometry Clinical analysis Sample preparation

"Determination Of Ultratrace Amounts Of Metal Ions By Graphite-furnace Atomic Absorption Spectrophotometry With Online Flow Injection Preconcentration. 1. Determination Of Copper In Snow, Rain And Other Water Samples"
Henliang Fenxi 1993 Volume 9, Issue 1-2 Pages 32-36
Yang, C.L.;Zhuang, Z.X.;Yang, P.Y.;Wang, X.R.

Abstract: Sample was pre-concentration 32-fold on a PTFE cartridge (1.5 cm x 2.4 mm) of CPPI (not defined) resin (self-made; 60 mesh) washed with 2 M HNO3, then transferred to a graphite-furnace by automated sample introduction. The heating cycle involved drying at 110°C for 50 s, ashing at 700°C for 10 s, atomization at 2000°C for 3 s and cleaning at 2300°C for 3 s. The calibration graph was rectilinear from 1 (detection limit) to 900 pg/g of Cu, and the RSD was 4%.
Metals Copper Rain Spectrophotometry

"Ultratrace-level Detection Of Arsenic And Selenium Using A Commercially Available Hydride Generator With Atomic Absorption Detection"
J. Autom. Methods Manag. Chem. 1983 Volume 5, Issue 4 Pages 193-196
R. W. WARD and P. B. STOCKWELL

Abstract: The Plasma-Therm continuous-flow hydride generator (illustrated) is based on the NaBH4 system. The apparatus has been applied in generation of the hydrides of, e.g., As and Se for determination by AAS or ICP-AES Detection limits by AAS are 0.04 and 0.07 ng mL-1 for As and Se, respectively, and response is rectilinear for up to 80 or 120 ng mL-1 of As or Se, respectively. The apparatus requires comparatively little operator expertise; it can accept and relay signals to an external computer, so facilitating control and data handling.
Arsenic Selenium Spectrophotometry Spectrophotometry

"Catalytic Determination Of Ultratrace Amounts Of Cobalt By Flow Injection Analysis"
J. Flow Injection Anal. 1985 Volume 2, Issue 1 Pages 40-49
Takuji KAWASHIMA, Takao MINAMI*,Masahumi ATA, Masaakira KAMADA* and Shigenori Nakano

Abstract: A new sensitive catalytic method has been developed for the determination of cobalt by flow injection analysis (FIA). N-Phenyl-p-phenylenediamine is oxidized to a yellow compound at pH 11 by hydrogen peroxide, and this compound is then converted to a blue-green compound(lambda max = 745 nm) with higher absorbance than the yellow compound in an acid solution of pH 0.5. The formation of the yellow compound is catalyzed by cobalt(II) and is extremely accelerated by Tiron(1,2-dihydroxybenzene-3,5-disulfonic acid) as an activator. By this catalytic effect, ultratrace amounts of cobalt can be determined. Sample volume, sampling rate, reaction coil length and reaction variables were examined by FIA. In this FIA method, a linear calibration curve for cobalt(II) was obtained in the range 0.04-0.20 ng/mL and the reproducibility was satisfactory with c.v.(%) of 3.2 and 4.0 for ten determinations of 0.08 and 0.16 ng/mL cobalt(II), respectively. The sampling rate was 30 samples/h. The method was applied to the determination of cobalt in seawater.
Cobalt Sea Spectrophotometry

"Flow Injection Analysis Of Ultratrace Sulfide In Water By Membrane Separation-chemiluminescence Detection"
J. Flow Injection Anal. 1987 Volume 4, Issue 1 Pages 15-19
Toyoaki Aoki, Toshi kazu Nosaka, Makoto Munemori

Abstract: A 2 mL sample is injected into a carrier stream of water (7.7 mL min-1) to which is then added 9 M H2SO4 (0.7 mL min-1). The stream then passes through the sleeve of a micro-porous membrane separator through the centre of which a stream (0.4 mL min-1) of luminol solution flows to a chemiluminescence cell with a photomultiplier tube. The calibration graph is rectilinear for 0.2 to 10 µM-S2- and the limit of detection is 80 nM; the coefficient of variation (n = 4) for 5 µM was 0.7%. In the determination of 0.16 ppm of S2-, 50 ppm of CO32- or NO2- depressed the signal by 9 or 7%, respectively. There was no interference from Co(II), Cr(III) or Cu(II).
Sulfide Environmental Chemiluminescence

"Flow Injection Analysis Of Ultratrace Free Chlorine In Water By Fluorimetric Detection"
J. Flow Injection Anal. 1987 Volume 4, Issue 2 Pages 98-102
Aoki, T.;Kato, K.;Munemori, M.

Abstract: Free Cl in water was determined by flow injection analysis with fluorimetric detection, by using nicotinamide(I) and Na2SO3 as reagents. The apparatus used is illustrated. The effects of I concentration, Na2SO3 concentration, temperature and injection volume were investigated. Response was rectilinear for 30 ppb to 80 ppm of free Cl, the detection limit was 0.8 ppb and the coefficient of variation (n = 7) was 2.0% at the 1.1 ppm level. Analysis of 30 samples h-1 was achieved. Various inorganic salts, Cr(VI), Mn(VII) and H2O2 did not interfere.
Chlorine Environmental Fluorescence

"Flow Injection Inductively Coupled Plasma Spectrometry. A New Strategy For Ultratrace Analysis"
J. Res. Natl. Bur. Stand. 1988 Volume 93, Issue 3 Pages 462-464
C. W. McLeod, Y. Zhang, I. Cook, and A. Cox, A. R. Date and Y. Y. Cheung

Abstract: Two methods of online trace enrichment by using activated alumina are studied. Chromate, PO43- and SO42- are determined by ICP-AES following enrichment on a column of acidic alumina and elution with aqueous NH3 or KOH. Results for determination of Cr(VI) and Cr(III) (not retained) in a reference water sample are tabulated. Cationic species, e.g., alkaline-earth-metal ions, are pre-concentrated on columns of basic alumina and eluted with 2 M HNO3 in a flow system with a carrier stream of aqueous 0.02 M NH3 and with samples buffered at pH 6 and containing 0.5 M tartaric acid as complexing agent. Results for determination of eight elements in a reference water sample agreed with certified values.
Anions Cations Chromate Phosphate Sulfate Metals, alkaline earth Trace elements Environmental Spectrophotometry

"Flow Injection Online Sorption Preconcentration In A Knotted Reactor For Electrothermal Atomic Absorption Spectrometric Determination Of Ultratrace Amounts Of Cobalt In Natural Waters"
Lab. Rob. Autom. 1997 Volume 9, Issue 4 Pages 191-199
Xiu-Ping Yan, Willy Van Mol, Freddy Adams

Abstract: A flow-injection on-line sorption pre-concentration-electrothermal atomic absorption spectrometric (ETAAS) method has been developed for the determination of ultratrace amounts of cobalt in natural waters. The pre-concentration was achieved by on-line complexation of cobalt with ammonium pyrrolidine dithiocarbamate and subsequent sorption of the complex onto the inner walls of a knotted reactor, made of a 0.5 mm i.d. and 100 cm long PTFE tubing. In order to reduce the eluate volume and to minimize dispersion, an air flow was used to drive the eluent for the elution of the adsorbed analyte and to dispel the eluate into the graphite tube. The adsorbed analyte complex was quantitatively eluted with 45 L of ethanol, and all the ethanolic eluate was successfully introduced at a relatively high flow rate (2.7 mL min-1) into an uncoated polycrystalline graphite tube without need of a platform nor a preheating step. ETAAS determination was performed in parallel with the pre-concentration of the next sample. With a sample consumption of 6.7 mL, an enhancement factor of 47 in comparison with direct injection of 45 L aqueous solution was obtained at a sampling frequency of 31 h-1. The detection limit (3 ) was found to be 2.8 ng L-1. The precision was 3% relative standard deviation (RSD) at the 0.2 g L-1 level (n = 11). The results obtained by the proposed method for a number of water standard reference materials are in good agreement with the certified values.
Cobalt Sea Spectrophotometry

"Determination Of Hydride-forming Elements At Ultratrace Levels By Flow Injection Hydride-generation Atomic Absorption Spectrometry With Online Ion-exchange Column Preconcentration"
Quim. Anal. 1989 Volume 8, Issue 2 Pages 191-199
Zhang, S.;Xu, S.K.;Fang, Z.L.

Abstract: Soil samples, prepared by refluxing for 2 h, and acidified, filtered water samples were merged with ammonium acetate buffer solution (0.2 M at pH 5 or 1 M at pH 7 for Se or Bi, respectively) and pre-concentrated on dual ion-exchange columns of D-201 (60 to 100 mesh) for Se(IV) or CPG-8Q (60 to 100 mesh) for Bi(III), and eluted with 1 M HCl. The eluates were mixed with 0.5% NaBH4 solution in 0.1% NaOH as reductant and carried by Ar carrier gas into a heated silica atomizer for AAS analysis. The limits of detection were 0.002 and 0.001 µg L-1 for Se(IV) and Bi(III), respectively, and the corresponding coefficient of variation were 1.1 and 1.0% (n = 11). Effects of co-existing ions are tabulated; interference from Cu(II) was overcome by the addition of 0.5% thiourea to the HCl eluent. Overall recoveries from water and soil water extracts were 90 to 108%, except for Bi(III) in waste water (78 to 90%).
Selenium Bismuth Waste Environmental Environmental Ion exchange Sample preparation Spectrophotometry