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

  • Publisher:
  • FAD Code: ATSP
  • CODEN: ASPND7
  • ISSN: 0195-5373
  • Abbreviation: Atom. Spectrosc.
  • DOI Prefix: NA
  • Language: English
  • Comments: Not available online - officially

Citations 61

"Use Of Sugar Cane Bagasse As Solid Phase Extractor For Cadmium Determination By FAAS"
Atom. Spectrosc. 2006 Volume 27, Issue 5 Pages 139-145
BORGES, Elisangela Cardoso Lima ; OLIVEIRA, A. P. ; GOMES NETO, José Anchieta ; MORAES, Mercedes de

Abstract: The present paper describes the use of sugar cane bagasse as solid phase extractor for cadmium determination after complexation of the analyte with ammonium diethyldithiophosphate (ADDP) and sorption of the Cd-DDP complexes on the solid support. The concomitants were separated using a flow injection analysis (FIA) system coupled to flame atomic absorption spectrometry (FAAS) for determination. The main parameters such as ADDP concentration, acid medium, flow rate, reaction coil length, and reaction time were investigated. The results obtained with HNO3 showed good accuracy and precision. The enhancement factor was 20.5 times for a 120-second pre-concentration time, and the analytical frequency was 25 determinations per hour. The calibration curve was linear over the concentration range of 1-40 ?g L-1 Cd with a LOD of 0.697 ?g L-1 Cd and a relative standard deviation of 0.96% after 12 sucessive measurements of 30 ?g L-1 Cd. The proposed method was evaluated for the FIA-FAAS analysis of certified reference materials (tomato leaves, spinach leaves, and bovine liver) and Cd-spiked foods (shrimp, sardine, tuna, chicken liver and bovine liver). Good recoveries (80.0-97.1%) for the Cd-spiked samples and certified reference materials were obtained. The results of bagasse-packed minicolumns were compared with Si-C18 packed minicolumns. The F-test was applied between Si-C18/Bagasse minicolumns, Si-C18/certified values, and bagasse/certified values. It was found that the results were in agreement with the certified values at a 95% confidence level.

"Determination Of Mercury Levels In Blood And Urine Of Occupationally Exposed Workers Using Flow Injection With Cold Vapor AAS"
Atom. Spectrosc. 2006 Volume 27, Issue 3 Pages 98-105
LOPEZ-COLON Jose Luis; LOZANO Rafael

Abstract: The high volatility and easy skin absorption of mercury make it a toxic substance that is difficult to control. A flow injection system for the determination of mercury based on a cold vapor atomic absorption spectrometry technique (CVAAS) is used to determine mercury in blood and urine samples. The study was carried out for four groups of workers exposed to elementary mercury: Dentists, dental assistants, laboratory and chloralkali workers and compared to a non-occupationally exposed group. The results show that only the dentist and chloralkali group showed mercury exposure. The safe levels of exposure indicated by ACGIH, Biological Exposure Indices (BEI), are 35 ?g/g creatinine (CR) for urine mercury (UHg) and 15 ?g/L for blood mercury (BHg). However, because of the immunological etiology found in experimental studies on animals, where inorganic mercury may induce autoimmune glomerulonephritis in the absence of dose-response studies for groups of immunologically sensitive individuals, it is not scientifically possible to set a level for mercury below which (in individual cases) mercury-related symptoms will not occur. The most exposed group, chloralkali, has mean levels of UHg and BHg of 19.4 ?g/g CR and 14.4 ?g/L, respectively. The dentist group shows a mean mercury concentration of 9.6 ?g/L in blood and 3.9 ?g/g CR in urine. This is significantly higher than the mercury concentrations found in the control group (7.4 ?g/L in blood and 2.0 ?g/g CR in urine) or in the dental assistant group (7.1 ?g/L in blood and 1.9 ?g/g CR in urine). There is no significantly statistical difference in these two last groups. For the chloralkali group, clearly exposed to vapor mercury, there appears to be a statistically significant correlation between blood and urine mercury (N=42; rho=0.586; p<0.001).

"Characterization Of Tire Bead Wire Coating With Special Emphasis On Tin Estimation Using An Atomic Absorption Spectrometer With A Flow Injection Analysis System (AAS-FIAS)"
Atom. Spectrosc. 2006 Volume 27, Issue 2 Pages 44-47
Mandal, N.

Abstract: Bead wires used by the tire industry are made up of steel and coated with a low level of copper and tin. The coating over steel is required for good adhesion between the rubber and the bead wire. Conventional flame atomic absorption spectrometer (FAAS) instrumentation cannot determine low levels (1-3%) of tin present in bead wire. In this paper, an attempt has been made to estimate the tin content and also to characterize quantitatively the coating pre-sent in bead wire using a flame atomic absorption spectrometer (FAAS) in combination with a flow injection analysis system (FIAS). Repeatability and reproducibility of the measurements were found to be acceptable for this type of analysis and the results are reported here.

"On-line Flow Injection Flame AAS Determination Of Cobalt In Soil And Sediment Samples With 5,7-dichloroquinoline-8-ol-embedded Polymeric Materials"
Atom. Spectrosc. 2006 Volume 27, Issue 2 Pages 35-43
PRAVEEN R. S.; DANIEL Sobhi; PRASADA RAO T.

Abstract: Dichloroquinoline-8-ol-embedded styrene-ethylene-glycol dimethacrylate polymer materials were prepared via the bulk, precipitation, and suspension polymerization methods using similar compositions. The polymerization was carried out by thermal means in the presence of 2,2?- azobisisobutyronitrile as initiator and 2-methoxy ethanol as porogen. The above synthesized polymer materials were characterized physically and morphologically by using the FTIR, TGA, CHN, and SEM techniques. These polymeric materials were packed into homemade µcolumns and used for on-line solid phase extraction (SPE) pre-concentration of trace amounts of cobalt. The pre-concentrated cobalt species were eluted with 0.01 mol L-1 of nitric acid and injected directly into the nebulizer of a flame atomic absorption spectrometer (FAAS) for quantification. The enrichment factors for bulk, precipitation, and suspension polymerization materials, were 12.5, 12.5, and 6.0, respectively, with a 1-min pre-concentration time and a sample throughput of 30 h-1. The detection limits corresponding to 3 times the standard deviation of the blank were found to be 10, 10, and 80 ?g L-1 with a precision of 2.1, 2.5, and 2.6% (RSD) for five successive determinations of 80 ?g L -1 of cobalt. Furthermore, the retention capacities determined by the batch method were 11.46, 11.42, and 8.52 mg of Co(II) per g of bulk, precipitation, and suspension polymerization materials, respectively. Thus, enrichment factor, detection limit, and retention capacities are in the order: precipitation ? bulk > suspension. No significant interference was observed from neutral electrolytes and 100-fold amounts of Fe(III), Ni(II), Mn(II), Cu(II), and Zn(II). In addition to testing the accuracy of the developed procedure for the determination of cobalt in certified reference materials of soil and marine sediments, the method was applied successfully to the determination of cobalt in real soil and sediment samples.

"Inorganic Mercury Determination In Whole Blood Using On-line Microwave Digestion With Flow Injection Mercury System (FIMS)"
Atom. Spectrosc. 2005 Volume 26, Issue 6 Pages 234-240
R Albalak, K Caldwell, R Jones, G Miller

Abstract: The ability to accurately determine inorganic mercury relative to total or organic mercury is essential for studies of human health effects and biomonitoring. This paper describes a flow injection mercury system (FIMS) with on-line microwave digestion for the determination of inorganic mercury in whole blood. Recovery of inorganic mercury in diluted bovine and human whole blood was compared with the results of on-line microwave digestion and without microwave digestion. The results suggest that on-line microwave digestion was necessary for the full recovery of inorganic mercury from human whole blood but was not necessary from bovine whole blood. The limit of detection, based on three standard deviations of a base blood material, was calculated to be 0.35 ?g/L (n=793). The relative standard deviation was 17% at 1 ?g/L of mercury in diluted whole blood (n=20) and 14% at 2 ?g/L (n=20). Throughput was approximately 17 samples per hour for two readings. Calibration was linear up to 150 ?g/L.

"FAAS Determination Of Palladium After FI On-line Micro-column Preconcentration And Separation With Dicyandiamide-formaldehyde Resin Immobilized Silica Gel"
Atom. Spectrosc. 2005 Volume 26, Issue 4 Pages 162-166
PENG LIU ; XIONGZHI WU ; ZHIXING SU ; QIAOSHENG PU

Abstract: A simple and selective method was developed for the routine determination of trace palladium in metallurgical samples using flow injection (FI) on-line pre-concentration and separation with flame atomic absorption spectrometry (FAAS). Pd was selectively pre-concentrated on a micro-column packed with a dicyandiamide-formaldehyde resin immobilized silica gel in a wide range of sample acidity (0.1-5.0 mol L-1). It was then effectively eluted into the FAAS with a thiourea solution. Coexisting anions with a concentration of 20.0 mg mL-1 and common metal ions of 5.0 mg mL-1 did not interfere with the determination of 0.1 ?g mL-1 of Pd at a sample flow rate of 4.8 mL min-1 for 60s. The limit of detection for Pd was 1.1 ng mL-1 with a relative standard deviation of not more than 3.0%. The proposed method was successfully applied for the determination of Pd in metallurgical samples and the results were in good agreement with the certified values.

"Flow Injection Determination Of Cd In Meat Samples Using A Continuous Lixiviation/preconcentration System Coupled To A Flame MS"
Atom. Spectrosc. 2005 Volume 26, Issue 3 Pages 110-116
CANCELA-PEREZ S.; YEBRA-BIURRUN M. C.

Abstract: A simple flow injection method is proposed, which combines continuous acid extraction, pre-concentration, and flame atomic absorption spectrometry for the determination of cadmium in meat samples. The dynamic acid extraction step was carried out by using a continuous ultrasound-assisted extraction system. The acid extract was pre-concentrated on-line on a mini-column packed with a chelating resin (Chelite P, with aminomethylphosphoric acid groups), and elution was carried out with hydrochloric acid. Once eluted, cadmium was continuously monitored by flame atomic absorption spectrometry. These steps were optimized applying an experimental design. The method allowed a total sampling frequency of 16 samples per hour. Good precision of the procedure was obtained [2.9%, expressed as relative standard deviation (RSD)], including a high enrichment factor (20.5), and detection and quantification limits of 0.014 and 0.067 ?g/g for 60 mg of sample, respectively. The accuracy of the proposed method was verified using CRM 183 Pig Kidney standard reference material; the results were in good agreement with the certified values. The analytical procedure was applied to the determination of trace amounts of cadmium in real meat samples.

"Determination Of Trace Copper And Nickel In Environmental And Biological Samples By Flow Injection On-line Microcolumn Preconcentration Flame AAS Using Acrylic Acid-grafted Polytetrafluoroethylene Fiber For Column Packing"
Atom. Spectrosc. 2005 Volume 26, Issue 1 Pages 34-39
WANG Zhao-Hui ; WANG Zhi-Peng ; ZHANG Zheng-Pu ; LIU Li-Wen ; YAN Xiu-Ping

Abstract: A newly prepared acrylic acid-grafted PTFE fiber sorbent (see reference 20) was extended to flow injection (FI) on-line microcolumn pre-concentration - flame atomic absorption spectrometric determination of trace copper and nickel in environmental and biological samples. On-line pre-concentration of trace analytes was achieved on the microcolumn packed with acrylic acid-grafted PTFE fibers, and the retained analytes were eluted with 1.0 mol L-1 HCl for on-line FAAS determination. The optimum pH range of the sample solution for pre-concentration of Cu(II) and Ni(II) was 3.6-5.6 and 4.4-6.4, respectively. The developed sorbent exhibited fairly fast kinetics for the adsorption of Cu(II) and Ni(II), permitting the use of high sample flow rates up to at least 10.8 mL min-1 for the FI on-line microcolumn pre-concentration system without loss of the retention efficiency. With a pre-concentration time of 45 s at a sample loading flow rate of 10 mL min-1, an enhancement factor of 48 for Cu and 23 for Ni, and a detection limit (3?) of 0.20 ?g L -1 for Cu and 0.25 ?g L-1 for Ni were achieved at a sample throughput of 55 h-1. Precision for 11 replicate measurements of 25 ?g L-1 Cu and 30 ?g L-1 Ni was 1.2 and 1.6% (RSD), respectively. The method was successfully applied to the determination of trace copper and nickel in environmental and biological samples.

"On-line Solid Phase Extraction Preconcentration Of Ultratrace Amounts Of Cobalt And Nickel In Soil And Human Hair Samples For Determination By Flow Injection Flame AAS"
Atom. Spectrosc. 2004 Volume 25, Issue 6 Pages 238-244
Starvin, A M; Biju, V M; Rao, T Prasada

Abstract: A flow injection on-line solid phase extraction (SPE) pre-concentration system, coupled to a flame atomic absorption spectrometer (FAAS), was developed for the determination of cobalt and nickel at the ?g/L levels. Cobalt and nickel were complexed with 2,3-dihydroxy naphthalene (DHN) in the pH range of 2.0-8.0 in the flow injection system and adsorbed onto a C18-bonded silica gel microcolumn. The pre-concentrated metal-DHN complexes were eluted with acidified methanol (pH ?2). The eluent was injected directly into the nebulizer of a FAAS for measurement. The enrichment factors were 725 and 600 for cobalt and nickel, respectively, with a 1-min pre-concentration time and a sample throughput of 30/h. The detection limits, corresponding to three times the standard deviation of the blank, were found to be 0.1 ?g/L with a precision of 2.5 and 2.6% (RSD) for five successive determinations of 10 ?g/L of Co and Ni, respectively. No significant interference was observed from neutral electrolytes, Fe, Zn, and Cu. In addition to testing the accuracy of the developed procedure for the analysis of nickel soil reference material (IAEA, Soil-7), the method was also applied successfully to the determination of Ni in soil and Ni and Co in human hair samples.

"Rapid Determination Of Zinc In Foods By Flow Injection Analysis With Flame AAS Using Gradient Calibration Method"
Atom. Spectrosc. 2004 Volume 25, Issue 5 Pages 221-225
ANZANO Jesus M. ; HEINEMANN Riana J. B. ; MIR Jos&eacute; Ma.

Abstract: A calibration method was developed using flow injection analysis (FI) with a Gradient Calibration Method (GCM). The method allows the rapid determination of zinc In foods (approximately 30 min) after treatment with concentrated sulphuric acid and 30% hydrogen peroxide, and analysis with flame atomic absorption spectrometry (FAAS). The method provides analytical results with a relative standard deviation of about 2% and requires less time than by conventional FI calibration. The electronic selection of different segments along the gradient and monitoring of the technique covers wide concentration ranges while maintaining the inherent high precision of flow injection analysis. Concentrations, flow rates, and flow times of the reagents were optimized in order to obtain best accuracy and precision. Flow rates of 10 mL/min were selected for zinc. In addition, the system enables electronic dilution and calibration where a multipoint curve can be constructed using a single sample injection.

"Rapid Determination Of Chemical Oxygen Demand By Flame AAS Based On Flow Injection On-line Ultrasound-assisted Digestion And Manganese Speciation Separation"
Atom. Spectrosc. 2004 Volume 25, Issue 4 Pages 191-196
Zhang, Z-Q; Yan, H-T; Yue, L

Abstract: A rapid flame atomic absorption spectrometty (FAAS) method for the determination of chemical oxygen demand (COD) is proposed. It is based on using ultrasonic wave to advance sample digestion by potassium permanganate and flow injection on-line speciation separation of manganese. In a digestion coil, placed in the ultrasonic and heating water bath, the sample was oxidized by acidic potassium permanganate to produce Mn2+. Passing through a cooling coil, Mn2+ was adsorbed on a cation-exchange micro-column, while the unreduced MnO4- passed through the micro-column to waste. Then the adsorbed Mn2+ was eluted reversely by 3 mol L -1 HCl and determined by FAAS. With a digestion temperature of 80? C and a digestion time of 30 s, the determination range was 3-300 mg L-1 COD and the detection limit was 1 mg L-1 COD, with a sampling frequency of 24 samples per hour. The relative standard deviation of the method was 2.7% (n=9). Chloride did not interfere up to the 1000 mg L -1 level. The proposed method was applied to the determination of COD in well, river, and pool water samples, and the results obtained are in agreement with those given by the standard methods.

"Flow Injection On-line Sorption Preconcentration Coupled With Cold Vapor Atomic Fluorescence Spectrometry And On-line Oxidative Elution For The Determination Of Trace Mercury In Water Samples"
Atom. Spectrosc. 2004 Volume 25, Issue 3 Pages 145-153
Yu, L-P; Yan, X-P

Abstract: A rapid, sensitive, and cost-effective method was developed for the determination of trace mercury in water samples by online coupling of flow injection (FI) sorption pre-concentration with oxidative elution to cold vapor atomic fluorescence spectrometry (CV-AFS). Trace Hg(II) in aqueous solution was pre-concentrated by on-line formation of mercury diethyldithiocarbamate complex (Hg-DDTC) and adsorption of the resulting neutral complex on the inner walls of a PTFE knotted reactor (KR). A mixture of 16% (v/v) HCl and 10% (v/v) H 2O2 was used as the eluent to remove the adsorbed Hg-DDTC from the KR, then convert online the Hg-DDTC into Hg(II) prior to its reduction to elemental mercury by KBH4 for subsequent on-line CV-AFS detection. The tolerable concentrations of Cd(II), Zn(II), AS(III), Se(IV), Fe(III), Co(II), Ni(II), and Cu(II) for the determination of 0.1 ?g L-1 Hg(II) were 0.1, 10, 0.1, 0.1, 0.7, 1, 0.3, and 0.2 mg L-1, respectively. With a sample loading flow rate of 3.1 mL min-1 for a 60-s pre-concentration, a detection limit (3?) of 4.4 ng L-1 was achieved at a sample throughput of 36 samples h-1. The precision (RSD, n = 11) was 1.7% at the 0.1-?g L-1 Hg (II) level. The method was successfully applied to the determination of mercury in a certified reference material, GBW(E) 080392, and a number of local natural water samples.

"Evaluation Of Sample Treatment For Simultaneous Flow Injection Hydride Generation And Determination Of As, Bi, Sb And Se By GFAAS"
Atom. Spectrosc. 2004 Volume 25, Issue 3 Pages 133-139
Freschi, C. D.

Abstract: A new method was developed for the simultaneous determination of As, Bi, Sb, and Se by flow injection hydride generation graphite furnace atomic absorption spectrometry. An alternative two-step sample treatment procedure was used. The sample was heated (80?C) for 10 min in 6 M HCl to reduce Se(VI) to Se(IV), followed by the addition of 1% (m/v) thiourea solution to reduce arsenic and antimony from the pentavalent to the trivalent states. With this procedure, all analytes were converted to their most favorable and sensitive oxidation states to generate the corresponding hydrides. The pre-treated sample solution was then processed in the flow system for in situ trapping and atomization in a graphite tube coated with iridium. The Ir permanent modifier remained stable up to 300 firings and new coatings were possible without significant changes in the analytical performance. The accuracy was checked for As, Bi, Sb, and Se determination in water standard reference materials NIST 1640 and 1643d and the results were in agreement with the certified values at a 95% confidence level. Good recoveries (94-104%) of spiked mineral waters and synthetic mixtures of As(III), As(V), Sb(III), Sb(V), Se(VI), and Se(IV) were also found. Calculated characteristic masses were 32 pg As, 79 pg Bi, 35 pg Sb, and 130 pg Se, and the corresponding limits of detection were 0.06, 0.16, 0.19, and 0.59 ?g L-1, respectively. The repeatability for a typical solution containing 5 ?g L-1 As, Bi, Sb, and Se was in the 1-3% range.

"Multielement Determination Using On-line Emulsion Formation And ICP-MS/ FAAS For The Characterization Of Virgin Olive Oils By Principal Component Analysis"
Atom. Spectrosc. 2004 Volume 25, Issue 1 Pages 1-12
Jimenez, M S; Velarte, R; Gomez, M T; Castillo, J R

Abstract: Several virgin olive oil samples from different Spanish origin denominations were analyzed for the multielement determination of Al, Ba, Bi, Ca, Cu, Mg, Mn, Na, Pb, and Sn with on-line emulsion formation by flow injection analysis and determination by ICP-MS and flame atomic spectroscopy. The data obtained from the automated multielement determination were treated with Principal Components Analysis to assess the feasibility of using the concentration of the different elements in the olive oil for classifying the oils according to geographical origin and the type of olive used. The statistical analysis carried out showed that Al, Ba, and Mn have a differentiating ability which permits separation of the olive oils analyzed according to their geographical origin and the type of olive employed, whereas Bi, Cu, Sn, and Pb are related to contamination and do not display differentiating capacity.

"Flow Injection AAS Determination Of Zinc In Milk Powder And Infant Formula Using Continuous Ultrasound-Assisted Dissolution For Soluble Solid Sample Preparation"
Atom. Spectrosc. 2003 Volume 24, Issue 6 Pages 218-221
MC YEBRA, A MORENO-CID, S CANCELA, RM CESPON

Abstract: A flow injection system for the continuous ultrasound-assisted dissolution of solid soluble samples (CUDS) has been developed for the dissolution of milk powder and infant formula samples. This system is connected on-line to a flow injection flame atomic absorption spectrometer for continuous zinc monitoring. This methodology allows the analysis of samples without sample pretreatment, thus avoiding time-consuming traditional sample preparation methods. The proposed methodology was validated by the analysis of a certified reference material (BCR-063R Skim Milk Powder). The results agreed well with the certified values. The method is very sensitive (limit of detection = 0.3 ?g/g) and precise (RSD = 0.4%) and was applied to real samples of milk powder and infant formula. The advantages of this methodology are discussed with respect to improvement in sample throughput, analytical performance, and analytical figures of merit.

"ICP-OES Determination Of Cobalt In Natural Water Using A Flow Injection System After Preconcentration On Activated Carbon"
Atom. Spectrosc. 2003 Volume 24, Issue 6 Pages 213-217
Farias, G.M.; Cerutti, S.; Gasquez, J.A.; Olsina, R.A.; Martinez, L.D.

Abstract: An on-line cobalt pre-concentration system is described for the ICP-OES determination of cobalt in drinking water in a flow injection system. The methodology developed is simple and rapid. Trace amounts of cobalt were pre-concentrated by sorption on a conical mini column packed with activated carbon (AC) at pH 9.5, with retention of 95%. The cobalt was removed from the conical mini column with 20% (v/v) nitric acid. An enrichment factor of 95-fold for a sample volume of 50 mL was obtained. The detection limit for the pre-concentration method proposed was found to be 20 ng L-1. The precision for 10 replicate determinations at the 5-?g L-1 Co level was 2.7% relative standard deviation, calculated from the peak heights obtained. The calibration graph pre-concentration method for cobalt species was linear with a correlation coefficient of 0.9994 at levels near the detection limits up to at least 100 ?g L-1. The method was successfully applied to the determination of cobalt in natural water samples.

"Flow Injection AAS Determination Of Cd, Cu, And Pb At Trace Levels In Wine Using Solid Phase Extraction"
Atom. Spectrosc. 2003 Volume 24, Issue 5 Pages 179-184
AP Fernandes, M De Moraes, J Neto

Abstract: A comparative study is reported between C18 bonded silica gel and powdered polyethylene (PE) as sorbent for Cd, Cu, and Pb determination using ammonium diethyldithiophosphate (ADTP) as the complexing agent in a flow injection system. The complexes were formed in 0.14 mol L-1 HNO 3 and processed in a simple flow system comprising a peristaltic pump, a manual injector-commutator, and a sorbent-packed mini-column. Ethanol was selected as the eluent and analytes in the eluate were determined by flame atomic absorption spectrometry. The optimum concentration of the complexing agent was 0.1% (m/v) ADTP for Cu and Pb determination using either C 18 or PE, and 0.25% (m/v) ADTP for Cd determination using PE. The sample loading flow rates were 5.0, 3.6, and 3.0 mL min-1 for Cu, Pb, and Cd, respectively. The best elution flow rate was 6.5 mL min-1 For a 60-sec pre-concentration time, the sampling rate was 40 h-1 and the enrichment factors of 33, 36, and 11 times (C18) or 18, 22, and 23 times (PE) were obtained for Cu, Pb, and Cd, respectively. The limits of detection (LOD) were 1.6 ?g L-1 Cu, 11 ?g L-1 Pb, and 2.0 ?g L-1 Cd using C18 or 2.9 ?g L -1 Cu, 19 ?g L-1 Pb, and 1.0 ?g L-1 Cd using PE, respectively. The relative standard deviations (n = 12) were typically <2%, <2%, and <6% for Cd, Cu, and Pb, respectively. The recoveries of Cd, Cu, and Pb added to wine samples varied from 96-99%, 97-102%, and 90-99%, respectively, using C18 or PE. Accuracy was checked for Cd, Cu, and Pb determination in six wine samples digested by block digestor and open-vessel microwave-assisted digestion systems. The results revealed that C18 was more efficient for Cu and Pb determination, while PE was the best sorbent for Cd.

"On-line Solid Phase Extraction Preconcentration Of Ultratrace Amounts Of Zinc In Fractionated Soil Samples For Determination By Flow Injection Flame AAS"
Atom. Spectrosc. 2003 Volume 24, Issue 4 Pages 118-124
CR PREETHA, VM BIJU, T PRASADA RAO

Abstract: A flow injection on-line solid phase extraction (SPE) pre-concentration system coupled to a flame atomic absorption spectrometer (FAAS) was developed for the determination of zinc at the ?g L-1 level. Zinc is complexed with 1-(2-thiazolylazo)-2-naphthol (TAN) in the pH range of 9.5-11.0 in the flow injection system and adsorbed onto a C18-bonded silica gel µcolumn. The pre-concentrated Zn-TAN complex was eluted with acidified methanol (pH-2). The eluent was injected directly into the nebulizer of a FAAS for measurement. The enrichment factor was 120 with a 1-min pre-concentration time and a sample throughput of 30 h-1. The detection limit corresponding to three times the standard deviation of the blank was 0.15 ?g L-1 with a precision of 2.5% (RSD) for five successive determinations of 5 ?g L-1 of Zn. No significant interference was observed from neutral electrolytes and cations of soil samples. The method was also applied successfully in the analysis of soils which were fractionated as per BCR (now Standards, Measurements and Testing Program) using both the direct and standard addition (SA) methods.

"Flame AAS Determination Of Total Chromium In Mussel Samples Using A Continuous Ultrasound-assisted Extraction System Connected To An On-line Flow Injection Manifold"
Atom. Spectrosc. 2003 Volume 24, Issue 1 Pages 31-36
MC YEBRA, A MORENO-CID, RM CESPON, S CANCELA

Abstract: Total chromium was extracted on-line from solid mussel samples using a simple, rapid, and continuous ultrasound-assisted extraction system (CUES). CUES is connected to a flow injection manifold, which permits the on-line flame atomic absorption spectrometric determination of chromium. The manifold for total chromium determination is the simplest possible because a volume of 83 µL of acid leachate was injected into a water carrier stream. An experimental design was used for optimization of the continuous leaching procedure. Compared to off-line ultrasonic-assisted extraction methods, the sonication time was reduced by a factor of 4-28. The method allowed a total sampling frequency of 11 samples per hour, with a relative standard deviation for the complete procedure of 1.7% [for a sample containing 2.9 ?g/g chromium (wet mass)]. Accuracy was verified using TORT-1 certified reference material and the procedure applied to the analysis of mussel samples.

"Indirect Determination Of Ciprofloxacin By Flow Injection Flame AAS Based On Forming Complex With Fe(III)"
Atom. Spectrosc. 2003 Volume 24, Issue 1 Pages 27-30
ZQ ZHANG, YC JIANG, HT YAN

Abstract: Based on the complexation reaction of ciprofloxacin with Fe(III) in a weak acid medium, a flame atomic absorption spectrometry (FAAS) method for the indirect determination of ciprofloxacin is proposed. In the flow injection on-line concentration and separation system, the ciprofloxacin solution reacted with Fe(III) to form the cation complex ciprofloxacin-Fe(III). This complex was then adsorbed on a cation-exchange mini column, while the excessive Fe(III) changed into anion (FeF6)3- and passed through the mini column to waste. The adsorbed ciprofloxacin-Fe(III) was eluted reversely with HNO3 to the nebulizer for measurement by FAAS. The absorbance of Fe(III) eluted from the mini column is proportional to the concentration of ciprofloxacin. With a reaction and adsorption time of 60 s and 100 s, respectively, the calibration curve was linear over the range of 5-100 ?g mL-1 and 0.5-80 ?g mL-1. The relative standard deviation was 2.6% and 3.2%, at an analytical throughput of 30 and 22 samples per hour, respectively. The method was found to be suitable for the determination of ciprofloxacin in pharmaceutical preparations and superior to previously reported HPLC methods because of the simple experimental conditions required.

"Selective Determination Of Sb(III) In Drugs By Flow Injection Hydride Generation AAS"
Atom. Spectrosc. 2003 Volume 24, Issue 1 Pages 15-21
De Moraes Flores, E M; Paula, F R; Da Silva, F E B; De Moraes, D P; Paniz, J N G; Dos Santos, E P; Dressler, V L; Bittencourt, C F

Abstract: In this work, a procedure is described for the selective determination of Sb(III) in commercial drugs based on pentavalent antimony. Antimony(III) was determined by flow injection atomic absorption spectrometry (FI-HG-AAS) in drugs injected for leishmaniasis treatment in South America. The following acids were studied: acetic, tartaric, citric, oxalic, and lactic. The optimized conditions for Sb(III) determination without interference from Sb(V) were: 20% (m/v) citric acid, 2.0% (m/v) sodium tetrahydroborate, 125 µL injection volume, and 180 cm for reactor length. Interference of As, Ni, and Pb on the Sb(III) analytical signal was also investigated. The detection limit was 0.95 ng and the characteristic mass 55 pg. The recovery values obtained using the proposed procedure for six commercial samples varied from 97.1-100.8%. The relative standard deviation was 3.8%. The proposed FI-HG-AAS procedure allows more than 60 determinations per hour. The optimized procedure was applied for quality control of pentavalent antimony-based drugs produced commercially in Brazil.

"Flow Injection Hydride Generation AAS For The Indirect Determination Of 6-mercaptoprine"
Atom. Spectrosc. 2002 Volume 23, Issue 5 Pages 160-164
Song, Y.R.;Wang, S.Z.;Wang, D.F.;Wu, H.;Zhou, X.

Abstract: A new flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS) procedure is presented for the indirect determination of the 6-mercaptoprine(6-MP) content in tablets, based on the precipitation reaction of 6-MP and Pb(II) to form the 6-MP=Pb complex. The influences of the operating conditions were examined. A standard calibration curve was used with a linear working range of 0.000-52.00 ng mL-1 (correlation coefficient R=0.9995). The Pb detection limit was 0.195 ng mL-1. The reliability of the procedure was established by repeated experiments with recovery ranging from 95.93-100.85%. The mechanism for 6-MP reacting with Pb(II) to form a deposit sample is also proposed.

"Determination Of Trace Lead In Water Samples By Flow Injection On-line Filterless Precipitation-dissolution Preconcentration Coupled With Flame AAS"
Atom. Spectrosc. 2002 Volume 23, Issue 5 Pages 154-159
QY YE, YAN LI, YAN JIANG, XP YAN

Abstract: A flow injection on-line filterless precipitation-dissolution system was developed for the FAAS determination of trace lead in water samples. On-line precipitation of trace lead was achieved by merging the sample solution with an ammonia solution. The resultant precipitates were collected onto the inner walls of the knotted reactor without filtration. A flow of 1 mol L-1 HNO3 was introduced to dissolve the precipitates and to deliver the analyte for on-line FAAS detection. With a sample loading flow rate of 3.5 mL min-1 for a 40-second pre-concentration, an enhancement factor of 37 with a sampling frequency of 60 h-1 was obtained. The detection limit (3 ?) was found to be 7.5 ?g L-1. The precision (RSD, n = 11) was 2.9% at the 50 ?g L-1 level. With the proposed method, the concentration of lead in a certified reference material (GBW 08607, River Water) was determined to be 0.96 ± 0.04 ?g g-1 using simple aqueous standards for calibration. These results are in good agreement with the certified value (1.00 ? 0.02 ?g g-1). This method was also successfully applied to the determination of trace lead in a variety of real water samples.

"Implementation Of AAS Methods For The Quantification Of Hg And Hexavalent Cr In Recycled Paper Used For Food Packaging"
Atom. Spectrosc. 2002 Volume 23, Issue 5 Pages 148-153
Soares, M.E.;Carneiro, C.;Bastos, M.L.

Abstract: Total mercury and hexavalent chromium were determined in recycled paper samples and cardboard packages intended to come in contact with food using atomic absorption spectrometry (AAS). For the determination of mercury, the samples were digested with a mixture of concentrated HNO3 and H2O2 and determined by cold vapor generation. Hexavalent chromium was extracted directly from the paper and cardboard with a solution of NaOH and determined by electrothermal atomization AAS. The detection limits were 0.38 and 0.50 µg/L for mercury and hexavalent chromium, respectively. The determinations were performed in the linear range of 0.38-10.0.

"On-line Solid Phase Extraction Of The 5,7-dichloroquinoline-8-ol Complex Onto C18 Bonded Silica Gel And Flame AAS Determination Of Cu In Seawater Samples"
Atom. Spectrosc. 2002 Volume 23, Issue 5 Pages 143-147
MARY GLADIS J, BIJU V M, PRASADA RAO T

Abstract: A flow injection on-line adsorption pre-concentration system coupled to flame atomic absorption spectrometry (FAAS) was developed for the determination of copper at the ?g L-1 level. Copper is complexed with 5,7-dichloroquinoline-8-ol in the pH range of 7.0-9.0 in the flow injection system and adsorbed onto the C18 bonded silica gel column. The pre-concentrated chelate complex was eluted with acidified methanol (pH >2) and injected directly into the nebulizer for atomization in an air- acetylene flame for measurement. With a 1-minute pre-concentration and sample frequency of 30 h-1, the enrichment factor was 100, which can be further improved by increasing the pre-concentration time. The detection limit was 0.05 ?g L-1 and the precision 1.4% at the 2 ?g L-1 Cu level. Validation of the developed method was carried out by analyzing certified seawater reference material (CASS 4) and determining copper at a concentration of 0.60±0.06 compared to a certified value of 0.592±0.05 ?g L-1. The method was also applied successfully to the analysis of seawater samples and the accuracy was tested by recovery measurements on spiked samples. No significant interferences from other substances usually occurring in seawater were found.

"Determination Of Selenium In Dietary Supplements By ETAAS And HG-AAS: A Comparative Study"
Atom. Spectrosc. 2002 Volume 23, Issue 4 Pages 129-134
Valiente, L.;Piccinna, M.;Ale, E.R.;Grillo, A.;Smichowski, P.

Abstract: A study was carried out to establish a reliable procedure for determining Se in dietary supplements. Three different brands of Se food supplements were evaluated. These supplements were digested with HNO3 and H2O2 using a two-cycle microwave procedure. Electrothermal atomic absorption spectrometry (ETAAS) and hydride generation-atomic absorption spectrometry (HG-AAS) techniques were selected for total Se determination. The adverse effects of potentially interfering metals that are normally present in these products were taken into account. In particular, the effect of Cu, Mn, and Zn on the Se signal was investigated. Copper reduces the Se signal significantly when HG-AAS was used for quantification. On the other hand, no interference effects were detected when ETAAS was used and for this reason it was selected as the best alternative to analyze the samples. The overall approach was tested in tablets of vitamins-minerals-amino acids, nutritional supplements and Se-enriched yeast. The selenium content ranged from 15.9±0.7 to 81.1±3.3 µg of Se per tablet. The data obtained demonstrate that the Se content reported on the labels of dietary supplements are often inaccurate. The detection limits were found to be 0.18 µg g-1 Se and 0.06 µg g-1 Se for ETAAS and HG-AAS, respectively. Precision was always better than 6%, while the recovery data ranged between 93 and 105%.

"Simple Method For The Selective Determination Of As(III) And As(V) By ETAAS After Separation With Anion Exchange Mini-column"
Atom. Spectrosc. 2002 Volume 23, Issue 3 Pages 92-97
Smichowski, P.;Valiente, L.;Ledesma, A.

Abstract: A simple approach is described for the separation and determination of inorganic arsenic species using solid phase extraction and electrothermal atomic absorption spectrometry (ETAAS). A Dowex 1-X8 anion exchange mini-column was used to separate As(Ill) and As(V). The chemical (pH, type and concentration of eluent) and physical (flow rate of sample and eluent) parameters affecting the separation were studied. Under optimized conditions, As(V) showed a strong affinity for the mini-column, while As(Ill) was collected in the effluent. As(V) was recovered by elution with 0.8 mol L-1 hydrochloric acid. The influence of other competing ions on the separation of As(III) and As(V) was also evaluated. The detection limit achieved for As(III) was 4 ng mL-1 and for As(V) 4 ng L-1. The relative standard deviation (%RSD) ranged from 0.7 - 1.3% for replicated tap, lake, and well water samples at the 20 ng mL-1 level. A pre-concentration factor of 100 was achieved for As(V) when 300 mL of water was processed. Arsenic recoveries (full procedure) ranged from 92-106%.
Speciation

"Preconcentration And Speciation Of Cr(III) And Cr(VI) In Water Samples Using Amberlite XAD-16 Resin And Determination By Flow Injection-flame AAS"
Atom. Spectrosc. 2002 Volume 23, Issue 2 Pages 44-51
Wuilloud, R. G. Wuilloud, G. M. de Wuilloud, J. C. A. Olsina, R. A.; Martinez, L. D.

Abstract: A method for the pre-concentration and speciation of chromium was developed. On-line pre-concentration and determination were obtained using flame atomic absorption spectrometry (FAAS) coupled with flow injection (FI). To determine the total chromium present in water samples, the chromium species were retained on an Amberlite XAD-16 resin as chromium-4-(2-Thiazolylazo)-resorcinol (Cr-TAR) complex, at pH 5.0. On the other hand, Cr(VI) was determined by selective formation of Cr-TAR complexes with the use of 1,2 cyclohexane-diaminetetracetic acid (CDTA) as masking agent of Cr(III). The Cr-TAR complexes were formed by heating the reagents at 90?C for 50 minutes and then retained on the resin. The Cr-TAR complexes were removed from the micro-column with ethanol. The Cr(III) concentration was determined by the difference between the total chromium concentration and that of Cr(VI). A sensitivity enhancement factor of 250 was obtained with respect to the chromium determination in aqueous medium by FAAS (50 for pre-concentration and 5 due to the use of ethanol as solvent). The detection limit for the pre-concentration of 50 mL of aqueous solution was 20 ng/L. The precision for 10 replicate determinations at the 2.0-?g/L Cr level was 3.8% relative standard deviation (RSD), calculated from the peak heights obtained. The calibration graph using the separation and pre-concentration method for chromium species was linear with a correlation coefficient of 0.9994 at levels near the detection limits up to at least 100 ?g/L. The method was successfully applied to the speciation of chromium in water samples.

"Sequential Preconcentration For The ETAAS Determination Of Pd In Human Urine"
Atom. Spectrosc. 2002 Volume 23, Issue 1 Pages 17-23
Costa, R.C.C.;Almeida, A.A.;Araujo, A.N.;Silva, V.L.

Abstract: A sequential injection analysis system for the determination of Pd in human urine by electrothermal atomic absorption spectrometry is described. The system runs fully independent of the autosampler of the equipment. The procedure is based on the retention of the complex formed between Pd and diethyldithiocarbamate on a column of silica C18 and elution with about 43 µL of ethanol directly into the graphite furnace. Using about 8 mL of sample resulted in a detection limit of 9 ng/L and a sampling rate of about 10 samples/h. Accuracy of the proposed methodology was evaluated by recoveries ranging between 91% and 100%. Repeatability assessed as %RSD in three samples with 26, 46, and 61 ng/L Pd concentration yielded 11.3, 5.8, and 4.8%, respectively.
Knotted reactor

"Flow Injection Flame Atomic Absorption Spectrometry For The Indirect Analysis Of Norfloxacin"
Atom. Spectrosc. 2001 Volume 22, Issue 6 Pages 429-432
ZQ ZHANG, YC JIANG

Abstract: A flame atomic absorption spectrometry (FAAS) method is proposed for the indirect analysis of norfloxacin, based on the complexation reaction of norfloxacin with Fe(III). In a flow injection on-line pre-concentration and separation system, a norfloxacin solution was mixed with a stream of Fe(III) solution to produce the cation complex norfloxacin-Fe(III). It was adsorbed on a µcolumn filled with a cation exchange resin, while the excessive Fe(III) reacted with NH4F to form anion (FeF6)3-, which then exited through the µcolumn as waste. The adsorbed norfloxacin-Fe(III) complex compound was eluted reversely with HNO3 to the nebulizer and measured by FAAS. The absorbance of Fe(III) is proportional to the concentration of norfloxacin. When the reaction and adsorption time was 60 s and 100 s, the calibration curve was linear over the range of 8 -180 ?g mL-1 and 3 -150 ?g mL-1, with a relative standard deviation of 1.4% and 2.9%, at an analytical frequency of 30 and 22 samples per hour, respectively. This method was applied to the analysis of norfloxacin in capsules and the results compared well with those provided by perchloric acid titrimetry.

"Use Of Low Temperature Ashing And Microwave Acid Extraction Procedures For As And Hg Determination In Coal, Coal Fly Ash, And Slag Samples By Cold Vapor/hydride Generation AAS"
Atom. Spectrosc. 2001 Volume 22, Issue 6 Pages 422-428
Moreda Pineiro, J.;Beceiro Gonzalez, E.;Alonso Rodriguez, E.;Gonzalez Soto, E.;Lopez Mahia, P.;Muniategui Lorenzo, S.;Prada Rodriguez, D.

Abstract: Methods for the determination of As and Hg in coal, coal fly ash, and slag samples involving microwave acid extraction and cold vapor/hydride generation AAS have been developed. Two microwave acid extraction procedures using aqua regia and aqua regia + hydrofluoric acid were studied. For samples with high organic matter content (coal samples), a low temperature ashing pre-treatment (LTA) (below 150°C) was carried out prior to microwave acid extraction. The results were compared to those obtained without a LTA pre-treatment. Satisfactory analytical recoveries were obtained for As, while around 18% of Hg was removed during the LTA pretreatment. Mercury cold vapor and arsenic hydride were generated from hydrochloric acid medium using sodium tetrahydroborate in a batch hydride generation system coupled to AAS. The LODs obtained were 0.20 and 0.15 µg L-1 for As and Hg, respectively. The accuracy was studied using NIST-1633b coal, NIST-1635 coal, and NIST-1632b coal fly ash reference materials. The methods were applied to several coal, coal fly ash, and slag samples.

"On-line Adsorption/preconcentration Using A Knotted Reactor For Total Hg Determination In Drinking Water By Flow Injection CV-AAS"
Atom. Spectrosc. 2001 Volume 22, Issue 5 Pages 398-404
de Wuilloud, J.C.A.;Wuilloud, R.G.;Gasquez, J.A.;Olsina, R.A.;Martinez, L.D.

Abstract: An on-line mercury pre-concentration and analysis system using atomic absorption spectrometry (AAS) and flow injection (FI) with cold vapor (CV) generation was studied. The mercury was retained as a mercury-2-(5-bromo-2-pyridylazo)-5-diethplaminophenol [Hg(II)-(5-Br-PADAP)] complex, at pH 9.2. The mercury complex was removed from the knotted reactor (KR) with 3 mol/L hydrochloric acid. An enrichment factor of 25 was obtained with respect to CV AAS. The detection limit for the pre concentration of 25 ml, aqueous solution was 5 ng/L. The precision, calculated at peak height for 10 replicate determinations at the 1 µg/L-Hg level, was 2.8% relative standard deviation (RSD): The calibration curve using;. the pre-concentration system for mercury was linear with a correlation coefficient of 0.9995 at levels near the detection limits up to at least 100 µg/L. The method was successfully applied to the determination of mercury in drinking water samples.

"FAAS Determination Of Gold And Palladium Using An On-line Separation And Preconcentration System Based On A High-selective Chelating Adsorbent"
Atom. Spectrosc. 2001 Volume 22, Issue 5 Pages 392-397
Liu, P.;Wu, X.Z.;Sun, Q.Y.;Su, Z.X.;Pu, Q.S.

Abstract: A 2-mercaptothiazoline immobilized silica gel (MTLSG) was: synthesized and used for flow injection (FI) on-line separation and pre-concentration, coupled with flame atomic absorption spectrometry (FAAS). Au(III) and Pd(II) were pre-concentrated onto a µcolumn packed with MTLSG and then directly eluted into the AAS with thiourea/HCl or thiourea solution, respectively. The base metal ions (25.0 mg mL-1) and anions (100.0 mg mL-1) did not interfere in the determination of Au(III) and Pd(II). The detection limits, for Au(III) and Pd(II) were 4.4 ng mL-1 and 7.5 ng mL-1, respectively, with a sample loading flow rate of 5.0 mL min-1 and a pre-concentration time of 60 s. The precision for 11 replicate determinations was 1.2% and 2.6% relative standard deviation (RSD), calculated with peak area measurements: The calibration curves for Au(III) and Pd(11): were linear with a correlation coefficient of 0.9997 and 0.9999 in concentration ranges. of 0.1 similar to 2.0 µg mL-1 and 0.1 similar to 3.5 µg mL-1, respectively. The method was successfully applied to the determination of Au(III) and Pd(II) in geological and metallurgical samples.

"Determination Of As, Sb, And Se In Acid Extracts From Coal, Fly Ash, And Slag Samples By Hydride Generation ETAAS"
Atom. Spectrosc. 2001 Volume 22, Issue 5 Pages 386-391
Moreda Pineiro, J.;Moscoso Perez, C.;Lopez Mahia, P.;Muniategui Lorenzo, S.;Fernandez Fernandez, E.;Prada Rodriguez, D.

Abstract: Methods for the determination of As, Sb, and Se in coal, fly ash, and slag samples involving microwave acid extraction, hydride generation, trapping, and atomization of the hydrides generated in a graphite furnace have been developed. Two microwave acid extraction procedures using aqua regia and aqua regia + hydrofluoric acid were compared. Hydrides were generated from hydrochloric acid medium using sodium tetrahydroborate. Zr-treated graphite tubes were used for the in situ pre-concentration of hydrides. generated. A collection time of 30 s and trapping temperatures of 800, 600, and 500°C were used for As, Sb, and Se, respectively. The atomization temperatures used were 2100, 1600,. and 2300°C, respectively. Characteristic masses of 40, 17, and 90 pg for As, Sb, and Se, respectively,, were achieved. The accuracy was studied using NIST-1633b (coal) and NIST-1632b (coal fly ash) reference materials. The methods were applied to several coal, coke, coal fly ash, and slag samples.

"Optimization And Validation Of Total Mercury Determination In Food Products By Cold Vapor AAS: Comparison Of Digestion Methods And With ICP-MS Analysis"
Atom. Spectrosc. 2001 Volume 22, Issue 5 Pages 371-378
Perring, L.;Andrey, D.

Abstract: The aim of this work was to optimize sample preparation and measurement conditions for the determination of mercury in food products to ensure concentrations below legal guidelines. The samples were prepared with a high-pressure asher or microwave digestion, then measured using cold vapor atomic absorption spectrometry. The reducing reagents tin(II) chloride and sodium borohydride were investigated to test their ruggedness and their influence on mercury measurement. The limits of determination/quantification, repeatabilities, reproducibilities, and recoveries were estimated on different foodstuffs. The results obtained by CV AAS were similar to those obtained by ICP-MS.

"Flow Injection Flame AAS Determination Of Ascorbic Acid Based On Permanganate Reduction"
Atom. Spectrosc. 2001 Volume 22, Issue 4 Pages 346-349
MC YEBRA-BIURRUN, RM CESPON-ROMERO, A MORENO-CID

Abstract: An indirect flow injection method for the determination of ascorbic acid in fruit juices is proposed. Permanganate in an acid medium was injected into an ascorbic acid stream which reduced Mn(VII) to Mn(II). The Mn(II) formed was retained online, proportional to the ascorbic acid concentration in the sample, on a poly(aminophosphonic acid) chelating resin, which is only selective for this oxidation state. The non-reduced Mn(VII) was determined by flame atomic absorption spectrometry. The proposed method allows the determination of ascorbic acid in the 0.2-34.5 ?g/mL range with a relative standard deviation of 2.2%, detection limit of 0.06 ?g/mL, and sample throughput of 90 samples/h. The results were consistent with those obtained by the reference method (AOAC).

"On-line Ion Exchange Preconcentration In A Sequential Injection Lab-on-valve Microsystem Incoporating A Renewable Column With ETAAS For The Trace Level Determination Of Bismuth In Urine And River Sediment"
Atom. Spectrosc. 2001 Volume 22, Issue 3 Pages 312-318
Wang, J.

Abstract: A sequential injection system for on-line ion exchange separation and pre-concentration of trace level amounts of metal ions with ensuing detection by electrothermal atomic absorption spectrometry (ETAAS) is described. Based on the use of a renewable microcolumn incorporated within an integrated lab-on-valve microsystem, the column is initially loaded with a defined volume of beads of an SP Sephadex C-25 cation exchange resin. After having been exposed to a metered amount of sample solution, the loaded bead suspension is precisely manipulated within the valve to allow reproducible elution of the retained analyte by 30 µL nitric acid (1:16,v/v) which, via air segmentation, are then transported into the graphite tube for quantification. The content of the used column is afterwards discarded and new column material is aspirated for the next run. The ETAAS determination is performed in parallel with the pre-concentration process of the ensuing sample. The performance of the system is demonstrated for the determination of bismuth. With 2.4 mL sample loading, an enrichment factor of 33.4, a detection limit of 27 ng L-1, along with a sampling frequency of 10 h-1 was obtained. The relative standard deviation was 2.3% for the determination of 2.0 mg L-1 Bi (n = 7). The procedure was validated by determination of bismuth in a certified reference material CRM 320 (river sediment) and by bismuth spike recoveries in two human urine samples.

"Determination Of Mercury In Blood By Cold Vapor Atomic Spectrometry"
Atom. Spectrosc. 2001 Volume 22, Issue 2 Pages 284-289
Lopez Colon, J.L.;Veiga, D.;Montel, A.;De Pradena, J.M.;Lozano, R.

Abstract: The determination of mercury in biological matrices, such as blood, urine, and hair, is an important indicator in the assessment of mercury contamination in the environment and at the work place. Non-reactive alkyl compounds with stannous salts have been used by some authors for the differential determination of inorganic and organic mercury in cold vapor atomic spectrometry (CVAAS). However, this procedure does not allow for complete digestion of blood, which is an essential condition for flow injection systems in order to avoid the generation of foam that would block the flow of the carrier gas. Thus, a suitable and easy-to-use routine method for the determination of mercury based on appropriate sample digestion, followed by automated flow injection cold vapor reduction with NaBH4, has been developed. The method was optimized by varying the carrier gas flow rate and the concentration of the diluent solution. A carrier now rate of 75 mL/min provides a high enough absorbance peak with adequate resolution in peak shape. Best results were obtained by diluting the digested samples and aqueous standards with 10% nitric acid and 20% sulfuric acid. The limit of detection for whole blood was 0.95 nmol/L, with a linear range up to 600 nmol/L. To determine the precision and accuracy of the method, three levels of Seronorm trace elements whole blood were analyzed. The precision had a mean value of 3.7%. The accuracy was confirmed with the analysis of 24 samples of unknown concentration from the Quebec Interlaboratory Quality Control Program.
Amalgamation

"Determination Of Wear Metals In Lubricating Oils Using Flow Injection AAS"
Atom. Spectrosc. 2001 Volume 22, Issue 1 Pages 250-257
Pignalosa, G.;Knochen, M.

Abstract: The feasibility of flow injection analysis (FIA) was explored for the determination of wear metals in used lubricating oil by atomic absorption spectrometry. The difficulty presented by the viscosity of the samples was overcome by injecting the oil sample with a lab-made motorized syringe into a stream of kerosene. In order to achieve a thorough mixing of the two streams, three specially packed reactor was designed. The stream carrying the diluted sample was then carried to an AA spectrometer. A computer-controlled system was developed for injection and data acquisition allowing partial automation of the process. The influence of several parameters (sample and carrier flow rates, reactor length) was studied. Copper and iron were chosen as model analytes. Calibration was performed with Conostan standards diluted with unused oil. The accuracy was evaluated by analyzing real oil samples for copper and iron in the range of 1 to 40 ppm. The results were compared with those obtained by AAS measurement with manual dilution, using the joint-confidence ellipse F-test for the regression straight-line. No significant differences were found at the 95% confidence level. Precision of the results was 2.6% (RSD). The analytical frequency attained was 30 hr-1, which could be doubled with some software modifications. The stability of the proposed system was demonstrated during a 60 minute test, finding no evidence of drift in either baseline or sensitivity.

"Chemometric Approach For The Optimization Of A Flow Injection Manifold Applied To The Determination Of Total Hg In Seafood By Cold Vapor AAS"
Atom. Spectrosc. 2000 Volume 21, Issue 6 Pages 229-233
JL CAPELO, I LAVILLA, C BENDICHO

Abstract: A flow injection manifold was optimized using factorial design for the determination of mercury in seafood after microwave- assisted digestion by cold vapor atomic absorption spectrometry. The 2v5?1 fractional factorial allowed to estimate main factor and two-factor interactions with only 16 experiments. The HCl flow rate displayed the highest influence on sensitivity, the effect being positive and independent of other factors. The sodium borohydride concentration showed a significant negative effect, which could not be individually interpreted as there was interaction between the reducing agent concentration and the reducing agent flow rate. This interaction arose from the different influence of the reducing agent concentration depending on the reducing agent flow rate. Low reducing agent concentration together with high reducing agent flow rate is recommended. The HCl concentration and carrier gas flow rate did not show any significant effect. With a sample loop of 500 µL, a LOD of 0.4 ?g L-1 could be reached, the precision expressed as the relative standard deviation for 20 ?g L-1 Hg solution being 1.5%. The manifold was applied to the determination of total Hg in five seafood samples, using microwave-assisted decomposition with the HNO3 + H2O2 mixture. The method was validated against two certified reference materials.

"Trace Level Determination Of Lead By Flame AAS Using On-line Separation And Preconcentration"
Atom. Spectrosc. 2000 Volume 21, Issue 6 Pages 225-228
Yebra-Biurrun, M C; Enriquez-Dominguez, M F; Garcia-Garrido, A; Moreno-Cid, A

Abstract: A flow injection (FI) on-line pre-concentration method was developed for the flame atomic absorption spectrometry (FAAS) determination of trace amounts of lead in alloy samples. Lead was pre-concentrated on a mini-column packed with a poly(aminophosphonic acid) chelating resin (PAPhA), and subsequently eluted using a small volume of hydrochloric acid (2 mol/L) directly into the nebulizer burner system of the spectrometer. The procedure resulted in an enhancement factor of 14. A detection limit of 6.3 ?g/L (3 ?) was obtained using a time-based technique with 30 s pre-concentration; a 2.1% RSD was readily achieved for 11 measurements of 50 ?g/L Pb. The sample throughput was about 80/h. The procedure was applied to the determination of lead in alloy samples with high tolerance to interferences, and the results obtained for standard reference materials were in good agreement with the certified values.

"Flame AAS Determination Of Copper In Urine Using A Flow Injection On-line Preconcentration System Based On A Polyamine Chelating Ion Exchange Column"
Atom. Spectrosc. 2000 Volume 21, Issue 5 Pages 187-193
Almeida, A.A.;Jun, X.;Lima, J.L.F.C.

Abstract: A flow injection system incorporating a polyamine chelating ion exchange column for the flame atomic absorption determination of copper in urine is proposed. At a 5 mL sample volume, the procedure yielded a detection limit of I µg/L and a sample frequency of 20/h. Repeatability (%RSD, n=10) was 0.9% at a 100-mug/L level and 1.4% at a 20-mug/L level. Reproducibility (%RSD; n=3) was 5% for a mean sample concentration of about 33.8 µg/L. For maximum accuracy, a rapid wet sample digestion with H2O2 had to be performed. Results obtained by the proposed methodology (n=20) were in good agreement with those provided by graphite furnace atomic absorption spectrometry.
Sensitivity Extraction

"ICP-OES Determination Of Rare Earth Elements In Silicate Rocks Using Ultrasonic Nebulization And On-line Ion-exchange Iron Separation"
Atom. Spectrosc. 2000 Volume 21, Issue 5 Pages 172-178
Lara, R. Olsina, R. A. Marchevsky, E. Gasquez, J. A. Martinez, I. D.

Abstract: Rare earth elements (REEs) were determined in geological samples by inductively coupled plasma optical emission spectrometry (ICP-OES) with on-line iron separation using flow injection (FI) with an ultrasonic nebulization system. The anion-exchange separation method of a hydrochloric system was applied to the separation of REEs from iron. The iron-chlorocomplexes were retained on an anion-exchange (Dowex 1X-8) micro-column (3.0 mm i.d. ? 50.0 mm bed length), while the analytes were introduced into the ultrasonic nebulization system. After iron removal, a 700-?L sample was injected into a water carrier stream. The system was found to have a detection limit of La 0.30 ?g/L; Ce 0.93 ?g/L; Nd 0.51 ?g/L; Sm 0.25 ?g/L; Eu 0.045 ?g/L; Gd 0.72 ?g/L; Er 0.12 ?g/L; Yb 0.01 ?g/L; Lu 0.006 ?g/L. The application of the method on Reference Materials GS-N (ANRT); AC-E (IGW), G-2, RGM-1, AGV-1 and SDC-1 (USGS) demonstrated that results were statistically indistinguishable from published values.

"Influence Of Additives On The Carryover Effects Of Hg During ICP-OES Analysis Of Immunoglobulines Samples"
Atom. Spectrosc. 2000 Volume 21, Issue 5 Pages 165-171
Benzo, Z.;Quintal, M.;Marcano, E.;Salas, J.;Gomez, C.;Garaboto, A.;Murillo, M.

Abstract: A method for the determination of mercury in immunoglobulins samples by inductively coupled plasma optical emission spectrometry (ICP-OES) is described, in which sample dilution with some additives was the only pretreatment prior to analysis. Different chemical reagents, such as deproteinization agents, and other additives, such as surfactants, were proven as potentially useful. Residual mercury signal after samples analysis was one of our main concern. Among the diluents studied, EDTA and Triton(R) X-100 showed more accurate results. The Hg concentration in the samples, using the proposed method, are in good agreement with those obtained of samples analyzed by the official method using Cold Vapor Atomic Absorption Spectrometry (CV-AAS) with partial and total destruction of the sample.

"New Approaches To The Direct Analysis Of Highly Saline Samples By FIA-ICP-MS"
Atom. Spectrosc. 2000 Volume 21, Issue 5 Pages 156-164
Jimenez, M.S.;Velarte, R.;Castillo, J.R.

Abstract: The direct FIA-ICP-MS determination of Al, As, Cr, Mn, Mo, Ni, Ph, Rh, Sb, Te, and V in saline matrixes with different total dissolved solids content (TDS) (0.03-30%) was studied. Sample introduction by FIA permits the nebulization of matrixes with higher TDS in the ICP-MS. In this way, the direct determination of Mo and Mn in a certified seawater sample (CASS-3) was successfully carried out and the results obtained were in good agreement with the certified values. The other elements studied were either available in very low concentrations or do not have certified values for the CASS-S sample. The study of the influence of the instrumental parameters, such as nebulizer gas flow and plasma power, showed that the intensity obtained for the different elements studied decreases with matrix concentrations of 3% TDS or more. The higher the saline concentration, the smaller a flow is needed to minimize the interferences caused by the matrix. With regard to plasma power, it was observed that an increase in power reduces both spectroscopic and non-spectroscopic interferences. A study of the recoveries showed that Al, As, Cr, bin, Mo, Ni, Pb, Rh, Sb, Te, and V can be determined directly by FIA-ICP-MS depending on the dissolved solids content. Mn and Mo can be determined directly in matrixes with 30% TDS or less; Sb and Pb with 15% TDS or less; Rh and Te with 3% TDS or less; ill and Cr with 0.3% TDS or less; and all elements cited can be determined directly in matrixes with 0.03% TDS.

"Determination Of Selenium In Biological Samples Using ICP-QMS"
Atom. Spectrosc. 2000 Volume 21, Issue 5 Pages 149-155
Boulyga, S.;Dombovari, J.;Becker, J.S.;Dietze, H.J.

Abstract: A method for the determination of selenium traces in plant tissue samples is described. Freeze-dried and homogenized biological samples mere decomposed with HNO3, HF and H2O2 by using closed-vessel microwave digestion under temperature and pressure control. NIST SRM 1577b Bovine Liver and NIST SRM 1547 Peach Leaves reference materials were investigated to optimize the analytical procedure. Selenium concentrations were measured with quadrupole-based inductively coupled plasma mass spectrometry (ICP-QMS) using external calibration and the isotope dilution method. A special solution introduction device combining pneumatic nebulization with hydride generation in the thin liquid film on the walls of the minicyclonic spray chamber was employed for sample introduction into the ICP-MS, which allowed the sensitivity for Se to be increased by up to one order of magnitude without increasing the memory effects. SRMs were doped with different amounts (0, 0.1, 0.2, 0.5 and 1.0 µg/g) of enriched Se-78 spike (98.58% of Se-78) before digestion to study the method performance and selenium losses during sample preparation. For a given matrix selenium losses were reproducible as follows: 9.9±1.6% for Bovine Liver SRM, 15.8±3.6% for Peach Leaves SRM and 20.0±4.5% for the real plant tissue samples. The detection limit for selenium calculated for solid plant tissue was 0.2 µg/g (3s -criteria, m/z=82, digestion 1:1000) using conventional pneumatic nebulization for solution introduction and 0.03 µg/g for a combination of pneumatic nebulization with hydride generation. Applying the method developed, a large number of plant tissue samples were analyzed to study selenium behavior and accumulation in the environment.
Selenium NIST 1577 NIST 1547 Mass spectrometry Reference material Volatile generation

"Determination Of As Species In Extracts Of The Chinese Medicines Realgar And Orpiment By Ion Chromatography And Hydride Generation GFAAS"
Atom. Spectrosc. 2000 Volume 21, Issue 4 Pages 143-148
He, B.;Jiang, G.B.;Zhang, M.;Xu, X.B.

Abstract: A comprehensive method for the determination of arsenic speciation using ion chromatography (IC) and hydride generation graphite furnace atomic absorption spectrometry (HG-GFAAS) is proposed. Arsenic species including arsenite As(III), arsenate As(V), monomethylarsenate acid (MMA), and dimethylarsenate acid (DMA) were separated on a column system which consisted of an AG11 guard column and an AS11 separation column connected in series with 5 mmol L-1 NaH2PO4 as the mobile phase. Fractions eluted from IC were collected and determined by HG-GFAAS. For a 20 µL injection, the detection limits (3s) were 0.25, 1.76, 0.28, and 9.78 ng mL-1 as As for As(III), As(V), MMA, and DMA, respectively. Bg application of this method, the presence of As(III), As(V), and DMA in various extracts of the Chinese medicines realgar and orpiment were determined.

"Enhancement Of Thallium Response By Flow Injection Hydride Generation AAS Using Palladium And Rhodamine B"
Atom. Spectrosc. 2000 Volume 21, Issue 4 Pages 136-142
Zhu, D.;Xu, S.K.

Abstract: A flow injection hydride generation atomic absorption spectrometric (FI-HGAAS) method was developed for the determination of thallium at the ng mL-1 levels. Palladium, an effective enhancement reagent, was added to the acidified sample solution. The presence of µamounts of Rhodamine B increased the hydride generation efficiency further. The acidified sample solution containing palladium and Rhodamine B merged with the aqueous sodium tetrahydroborate solution at room temperature. The generated gaseous phase was separated in a gas-expanded gas-liquid separator and was led directly into a quartz tube atomizer at 1000°C via the Ar carrier gas for detection by AAS. Chemical and flow injection (FI) parameters for the hydride generation of thallium were optimized, including the concentration of the enhancement reagents, acidity of sample solution and carrier solution, NaBH4 concentration. reaction coil length, sample volume, carrier gas flow rate, and flow rate of the carrier as well as the reagent stream. With the optimized conditions, the precision was 0.9% RSD (200 ng/mL, n=11), with a sampling frequency of 120/h. A detection limit of 3.4 ng/mL T1 (3s) was obtained with a sample volume of 500 µL. The interferences from coexisting elements were studied. The recoveries of thallium in water samples by spiking the samples with 100 ng/mL of thalium were in the 101-109% range.

"Determination Of Antimony(III) By Flame AAS After Microcolumn Preconcentration On DETA Sorbent"
Atom. Spectrosc. 2000 Volume 21, Issue 4 Pages 128-131
Garbos, S.;Bulska, E.;Hulanicki, A.

Abstract: Selective sorption of Sb(III) on a microcolumn packed with DETA sorbent with grafted diethylenetriamine groups in a flow injection (FT) system was used for the determination of Sb(III) by flame atomic absorption spectrometry (FAAS). The sorbed antimony was directly eluted with HNO3 and determined on-line by FAAS. The detection limit of FI-FAAS procedure for antimony was 0.9 µg/L (3s) and was comparable to 0.8 µg/L for the direct injection GFAAS. The precision of the Sb determination (relative standard deviation, n=5) at the concentration level of 10 µg/L was 5.2%. Since total antimony was directly determined by graphite furnace atomic absorption spectrometry (GFAAS), the Sb(V) concentration could be calculated by the difference. The FI-FAAS procedure and GFAAS technique were applied for speciation determination of inorganic antimony in spiked oligocene water sampled from a well, which reaches the layer of rocks formed during the oligocene period.

"Flame Atomic Absorption Spectrometry For The Automatic Indirect Determination Of Ascorbic Acid Based On Flow Injection And Reduction Of Chromate"
Atom. Spectrosc. 2000 Volume 21, Issue 3 Pages 100-104
Zhiqi Zhang, Yucheng Jiang

Abstract: A very simple flame atomic absorption spectrometry method has been developed for the indirect determination of ascorbic acid using a flow injection system based on the redox reaction between chromate and ascorbic acid in acid medium. The Cr(III), produced by Cr(VI) bring reduced with ascorbic acid, is adsorbed on a cation exchange resin micro-column, then eluted by 3 mol L-1 nitric acid to the nebulizer and measured by name atomic absorption spectrometry. The absorbance of Cr(III) is proportional to the concentration of ascorbic acid in the sample. When the reaction and adsorption time reached two minutes, a calibration graph ranging from 0.3 to 60 µg mL-1 of ascorbic acid was obtained, with a relative standard deviation of 2.5% at 20 samples per hour. This method has been applied to the determination of ascorbic acid in Vitamin C tablets, Vitamin C injections, and vegetables. The results obtained in the analysis compare well with those provided by lodimetry.

"The Determination Of Phosphorus And Other Elements In Plant Leaves By ICP-MS After Low-volume Microwave Digestion With Nitric Acid"
Atom. Spectrosc. 2000 Volume 21, Issue 2 Pages 42-45
Esslemont, G.;Maher, W.A.;Ford, P.;Krikowa, F.

Abstract: A procedure for measuring phosphorous in plant leaves is described. Dry-leaf homogenates (<0.1g) were placed in 7 mL Teflon vessels with nitric acid (1 mL), microwave digested using the following program: 600 W, 2 min; 0 W, 2 min; 450 W, 45 min, then analyzed by inductively coupled plasma mass spectrometery (ICP-MS). Recoveries were verified by analyzing four plant certified reference materials (CRMs) in parallel with two established procedures for measuring phosphorus: (a) flow injection analysis (FIA) after catalyzed block digestion with sulphuric acid, and (b) FIA after digestion with sulphuric acid and hydrogen peroxide. The ICP-MS procedure allowed relatively simple, rapid analysis of phosphorus that was accurate to within±15% of certified values, with detection limits (5 µg/g) and precision (relative standard deviation = 4-9%) equivalent to or better than the other procedures. Furthermore the ICP-MS procedure allowed the accurate determination simultaneously with phoshorus.

"Speciation Of Sb(III) And Sb(V) By Hydride Generation High-resolution ICP-MS Combined With Prereduction Of Sb(V) With L-cysteine"
Atom. Spectrosc. 2000 Volume 21, Issue 1 Pages 30-36
Feng, Y.L.;Narasaki, H.;Tian, L.C.;Chen, H.Y.

Abstract: A method of hydride generation inductively coupled plasma mass spectrometry combined with the pre-reduction of antimony(V) with L-cysteine was established for the simultaneous speciation of inorganic antimony(III) and antimony(V) species in water. It was proved that ppt levels of antimony(V) can be reduced linearly to antimony(III) with L-cysteine within 6 minutes. Antimony(III) in solution was determined twice after 2 and 6 minutes reaction time, respectively. The concentrations of antimony(III) and antimony(V) were obtained, respectively, by a relationship between the antimony(V) concentration and the antimony(III) concentration, determined after 6 minutes, as well as the difference of two antimony(III) concentrations, determined after 2 and 6 minutes, respectively. Detection limits of the method for Sb(III) and Sb(V) were 4.2 ng/L and 17 ng/L, respectively. The relative standard deviation for ten determinations of a solution containing 100 ng/L Sb(V) was 11.0% and for a solution containing 100 ng/L Sb(III) it was 9.04%. The method nas finally applied to determine antimony(III) and antimony(V) in Aragawa river water samples taken near Tokyo Bay. Recoveries of the method were between 94-113% for Sb(III) and 91-111% for Sb(V), respectively.

"A Sequential Injection On-line Column Preconcentration System For Electrothermal AAS Determination Of Thallium In Geochemical Samples"
Atom. Spectrosc. 2000 Volume 21, Issue 1 Pages 17-22
Xu, Z.R.;Xu, S.K.;Fang, Z.L.

Abstract: A sequential injection system for on-line sorbent extraction pre-concentration in electrothermal atomic absorption spectroscopy was developed for the determination of trace thallium in geochemical samples. The TlBr4-1 complex was adsorbed on a 20 µL micro-column (located at the tip of the furnace sampling probe) packed with XAD-8 resin. After sequentially aspirating separate zones of acetone, rinsing acid, and sample (pretreated with bromine) into a 2.5-m long, 1-mm i.d. holding coil, the flow was reversed and directed to the column. Sample loading, analyte adsorption, column rinsing and analyte elution were achieved within a single reversed syringe stroke. The adsorbed analyte was eluted into the furnace with 50 µL acetone. Mutual mixing between sample, rinsing acid, and eluent were prevented by separating the zones with small air segments during metering. Tightening of column packing was avoided by a slight back-suction through the column after each operational cycle. With 1 mL sample loading, an enrichment factor of 15 was obtained with a detection limit of 18 ng/L thallium (3s). A precision of 2.4% RSD (n=11, 4 µg/L) and a sampling frequency of 11/hour were achieved. The method was applied to the analysis of geochemical samples. The results were in good agreement with the certified values of standard reference geochemical materials.

"Determination Of Total Mercury In Natural Gas Liquid And Condensate By Carbon Adsorption And Slurry Sampling ETAAS"
Atom. Spectrosc. 1999 Volume 20, Issue 6 Pages 224-229
Shiowatana, J.;Siripinyanond, A.;Waiyawat, W.;Nilmanee, S.

Abstract: A method for the determination of total mercury in natural gas liquid (NGL) and condensate (NGC) was delveloped. The trace amount of mercury was concentrated by adsorption on activated carbon powder, which was subsequently filtered and determined using the slurry sampling electrothermal atomic absorption technique. A concentration factor of up to 1000-fold was obtained in the pre-concentration step. Triton X-100 at 5000 µg/m L was necessary to disperse the adsorbed carbon powder in order to obtain a homogeneous slurry. Palladium was used as the chemical modifier in the ETAAS determination. Activated carbon could play the same role as ascorbic acid to facilitate palladium to stabilize the mercury and to enhance the sensitivity. The recovery of spiked mercury was found to be better than 90%. The repeatability and detection limit for NGL were found to be 8.4% and 2.0 ng/mL, respectively.

"ICP-OES Determination Of Trace Elements In Salinated Water Samples"
Atom. Spectrosc. 1999 Volume 20, Issue 6 Pages 217-223
Mitko, K.;Bebek, M.

Abstract: The analysis of highly salinated waters is a difficult process due to their complexity and wide range of chemical composition. A procedure for the fast, effective, and simultaneous determination of a wide range of elements varying in concentrations from trace levels Up to hundreds of grams per liter was succesfully performed. An ICP-OES instrument, equipped with a dual-view plasma torch, Echelle grating, and semiconductor detector, was used. The procedure concerning the determination of trace elements in the presence of at least several hundreds of mill-equivalents per liter of sodium and chlorides, and at least meq/L of calcium and magnesium as well as others ions is described.

"Optimization Of Parameters For Trace Inorganic Mercury Determination In Urine By Flow Injection Cold Vapor AAS"
Atom. Spectrosc. 1999 Volume 20, Issue 5 Pages 186-190
Sakuma, A.M.;de Maio, F.D.;Utishiro, R.Q.;Kira, C.S.;Carvalho, M.D.H.;Lichtig, J.

Abstract: The parameters of a flow injection mercury cold vapor atomic absorption spectroscopy system were optimized with respect to reagent concentration, carrier gas flow rate, acid carrier rate, and reaction coil length. Urine samples from workers exposed to mercury vapor as well as a urine reference standard were analyzed. It was shown that urine from workers exposed to elementary mercury vapor contains only inorganic mercury(II). The best conditions for the determination of inorganic mercury in urine included the following parameters: 500 µL sample volume, 300 mm reaction coil length, 80 mL/min carrier gas flow rate, 120 rpm pump speed, SnC2 5% (w/v) reductant solution in 5% (V/V) HCl, and HCl 3% (w/v) acid carrier.

"A Protocol For The Multielemental Analysis Of Trace Metals In Food Samples By Flow Injection Coupled To ICP-MS"
Atom. Spectrosc. 1999 Volume 20, Issue 5 Pages 174-179
Harrington, C.F.;Elahi, S.;Ponnampalavanar, P.;DSilva, T.M.

Abstract: A protocol, based on microwave digestion, followed by flow injection coupled to inductively coupled mass spectrometry (FI-ICP-MS) was developed for the simultaneous determination of up to 17 metals present In food digests. A number of different signal acquisition methods were evaluated in terms of precision, accuracy, and detection limit. Studies were also carried out to assess the maximum number of isotopes that could be determined without degradation of the detection limits. The method, which involved a combined nitric acid-hydrogen peroxide microwave digestion step, was validated using an oyster tissue certified reference material (NIST 1566a). The results were in good agreement with the certified values. The applicability of the method to the determination of trace metals in foodstuffs was tested by the multielemental analysis of mackerel, pig liver, and digestive biscuit digestates. The developed procedure gave detection limits (defined as 3 times the standard deviation of the blank concentration) of: Al = 1.46, B = 1.97, V = 0.11, Cr = 1.36, Co = 0.15, Ni = 0.59, As = 0.83, Sr = 0.08, Mo = 0.44, Cd = 0.16, Sn = 0.39, Ba = 0.07 and Pb = 0.27 (all ng g-1): These detection limits are comparable with a more time-consuming method using off-line dilution.

"Tin Determination In Seawater By Flow Injection Hydride Generation Atomic Absorption Spectroscopy"
Atom. Spectrosc. 1999 Volume 20, Issue 3 Pages 120-125
Bermejo Barrera, P.;Ferron Novais, M.;Gonzalez Campos, G.;Bermejo Barrera, A.

Abstract: A method for the trace determination of tin in seawater samples by a hydride generation technique using a flow injection system coupled with AAS was investigated. Tin hydride was generated using 0.4% NaBH4 in 0.2% NaOH as the reductant. The carrier solution was 5.6 * 10^-2 M HCl. The tin hydride generated was carried to the quartz cell by an :argon stream flow of 100 mL/min, where it was atomized at 900°C. Peak height was used for measurement of the analytical signal. a detection limit of 130 ng/L was obtained for a 500 µL sample volume. The precision was between 2.0 and 9.0%, and analytical recovery was close to 100%.
Preconcentration

"Determination Of Arsenic And Selenium In Seawater By Flow Injection Vapor Generation ETV-ICP-MS"
Atom. Spectrosc. 1999 Volume 20, Issue 3 Pages 79-85
Lam, J.W.;Sturgeon, R.E.

Abstract: Arsenic and selenium (IV) were determined in seawater following hydride generation (HG) by reaction with NaBH4 in an automated flow injection system. The hydrides were trapped on reduced palladium in a graphite furnace (ETV) and subsequently vaporized into an ICP for MS detection. This HG-ETV-ICP-MS approach afforded blank-limited absolute detection limits of 7 pg for As and 70 pg for Se, using 0.5 and 10 mL sample volumes, respectively, permitting their determination in samples of NASS-4 and NASS-5 seawater reference material. Precision of determination was 2.5% RSD for As at 1 µg/L and 10% for Se at 20 ng/L. Sample throughput was 8/h for As and 5/h for Se with interference-free quantitation of samples with the use of a standard calibration curve.

"Automatic Determination Of Metals In Parenteral Solutions By FIA-AS"
Atom. Spectrosc. 1999 Volume 20, Issue 1 Pages 39-43
Dol, I.;Espinola, G.;Knochen, M.

Abstract: An automatic lab-made system involving the use of flow injection analysis (FIA) was designed and constructed for the determination of sodium, potassium, calcium, and magnesium in parenteral solutions by flame atomic absorption and emission spectrometry. The system carries out the necessary dilutions and addition of spectroscopic buffers as well as data acquisition under software control from a personal computer. Good recoveries, precision and stability were found, suggesting its use for the automation of quality control of parenteral solutions in the pharmaceutical industry.

"Improved Sample Throughput Using Flow Injection Rapid Microsampling For ICP-MS"
Atom. Spectrosc. 1999 Volume 20, Issue 1 Pages 1-5
Ebenezer Debrah and Jean-Fran&ccedil;ois Alary

Abstract: The sample throughput capability for a commercial Inductively Coupled Plasma Mass Spectrometer (ICP-MS) Flow Injection (FI) system is improved by a newly developed flow injection control software. Taking advantage of the relative addressing mode recently implemented in the software, the autosampler probe can be moved to the next sample position while the previous sample is being measured by the ICP-MS. Combining this approach with a slightly modified flow injection rapid microsampling manifold, a throughput of better than 160 samples per hour is achieved with good precision. With a sample volume of 200 µL, the detection limits for selected elements meet or exceed the detection limit requirements of the United States EPA Method 200.8. The sample washout time is better than 10 s. Very good agreement between the certified values and the experimental values using this approach were obtained for both the semiquantitative and quantitative modes of analysis.