Flow Injection On-line Sorption Preconcentration Research Articles

Determination of Trace Inorganic Mercury in Mineral Water by Flow Injection On-line Sorption Preconcentration-Cold Vapor Atomic Fluorescence Spectrometry

Abstract Flow injection on-line sorption preconcentration and separation in a knotted reactor (KR) was coupled to cold vapor atomic fluorescence spectrometry for the determination of trace mercury in mineral water. Mercury was preconcentrated by on-line formation of mercury diethyldithiocarbamate complex (Hg-DDTC) and absorption of the resulting neutral complex on the inner walls of a knotted reactor. A 20% (v/v) HNO 3 solution heated by Electromagnetic induction heating technique was used as eluent to remove the absorbed Hg-DDTC from the KR, and then the vapor mercury generated by mixing the resulting solution and KBH 4 was determined on-line by cold vapor atomic fluorescence spectrometry. The 20% HNO 3 was used as both the efficient eluent and the required acidic medium for subsequent mercury vapor generation. Using 20% HNO 3 instead of conventional organic solvent as eluent, the proposed method is simple, easy operational and environmental friendly. Under the optimal experimental conditions, the sample throughput was approximately 30 per hour with the enhancement factor of 35. The detection limit of mercury was 2.0 ng l −1 . The precision (RSD, n = 11) was 2.2% at the 0.1 μg l −1 Hg 2+ level.

Determination of arsenic in foods by flow injection on-line sorption pre-concentration with hydride generation atomic fluorescence spectrometry

A method was developed for the determination of total arsenic in foods using flow injection on-line sorption coupled with hydride generation atomic fluorescence spectrometry (HG-AFS) using a cigarette filter as the sorbent material. After reducing As(V) to As(III) by using L-cysteine, the determination of total arsenic was achieved through on-line formation and retention of the pyrrolidine dithiocarbamate arsenic complex (As(III)–PDC) on the cigarette filter, which was packed in the pre-concentration column and total arsenic was determined by HG-AFS. The analytes were eluted with 1.68 mol l−1 HCl from the sorbent material. With consumption of 22 ml of the sample solution, an enrichment factor of 25.6 was obtained at a sample throughput of 11.6 h−1. The detection limits (3 standard deviations) and the precision (relative standard deviation) in foods ranged from 2.5 to 9.9 ng g−1 and from 1.1 to 2.2%, respectively. The method was used to determine arsenic in carrot, mushroom, chicken tissue, cod fish, rice, common carp and shrimp.

Determination of As(III) and As(V) in water samples by flow injection online sorption preconcentration coupled to hydride generation atomic fluorescence spectrometry

A method was developed for the determination of arsenite [As(III)] and arsenate [As(V)] in water samples using flow injection online sorption coupled with hydride generation atomic fluorescence spectrometry (HG-AFS) using a cigarette filter as the sorbent. Selective determination of As(III) was achieved through online formation and retention of the pyrrolidine dithiocarbamate arsenic complex on the cigarette filter, but As(V) which did not form complexes was discarded. After reducing As(V) to As(III) using L-cysteine, total arsenic was determined by HG-AFS. The concentration of As(V) was calculated by the difference between As(III) and total arsenic. The analytes were eluted from the sorbent using 1.68 mol L−1 HCl. With consumption of 22 mL of the sample solution, the enrichment factor of As(III) was 25.6. The detection limits (3σ/k) and the relative standard deviation for 11 replicate determinations of 1.0 ng mL−1 As(III) were found to be 7.4 pg mL−1 and 2.6%, respectively.

Preconcentration of inorganic antimony(III) in environmental samples by PSTH-Dowex microcolumn and determination by FI-ETAAS

A flow injection on-line sorption preconcentration system has been synchronously coupled to an electrothermal atomic absorption spectrometry (ETAAS) system for the selective determination of trace amounts of Sb(III) in water, soil and plant. The determination was achieved by selective complexation and sorption of Sb(III) with [1,5-bis(2-pyridyl)-3-sulphophenyl methylene thiocarbonohydarzide (PSTH) immobilized on an anion-exchange resin (Dowex 1× 8-200)] at a wide range of pH, quantitative elution with 50 μl of 2 M HNO 3 and subsequent ETAAS detection. ETAAS determination of the analyte was performed in parallel with the preconcentration of the next sample. Using a preconcentration time of 60 s and a sample loading flow rate of 2.8 ml min −1, an enhancement factor of 12 was obtained in comparison with direct injection of 50 μl aqueous solution, resulting in a sampling frequency of 31 samples h −1. The detection limit (3 s) was 2 μg l −1 and the precision was 3.1% (R.S.D.) for 11 replicate determinations at 10 μg l −1. The accuracy of the proposed method was demonstrated by analyzing one certified sample and different spiked samples.

Non-chromatographic speciation analysis of mercury by flow injection on-line preconcentration in combination with chemical vapor generation atomic fluorescence spectrometry

A novel non-chromatographic approach for direct speciation of mercury, based on the selective retention inorganic mercury and methylmercury on the inner wall of a knotted reactor by using ammonium diethyl dithiophosphate and dithizone as complexing agents respectively, was developed for flow injection on-line sorption preconcentration coupled with chemical vapor generation non-dispersive atomic fluorescence spectrometry. With the sample pH kept at 2.0, the preconcentration of inorganic mercury on the inner walls of the knotted reactor was carried out based on the exclusive retention of Hg–DDP complex in the presence of methylmercury via on-line merging the sample solution with ammonium diethyl dithiophosphate solution, and selective preconcentration methylmercury was achieved with dithizone instead of ammonium diethyl dithiophosphate. A 15% (v/v) HCl was introduced to elute the retained mercury species and merge with KBH 4 solution for atomic fluorescence spectrometry detection. Under the optimal experimental conditions, the sample throughputs of inorganic mercury and methylmercury were 30 and 20 h − 1 with the enhancement factors of 13 and 24. The detection limits were found to be 3.6 ng l − 1 for Hg 2+ and 2.0 ng l − 1 for CH 3Hg +. The precisions (RSD) for the 11 replicate measurements of each 0.2 μg l − 1 of Hg 2+ and CH 3Hg + were 2.2% and 2.8%, respectively. The developed method was validated by the analysis of certified reference materials (simulated natural water, rice flour and pork) and by recovery measurements on spiked samples, and was applied to the determination of inorganic mercury and methylmercury in biological and environmental water samples.

Flow injection on-line sorption preconcentration coupled with hydride generation atomic fluorescence spectrometry using a polytetrafluoroethylene fiber-packed microcolumn for determination of Se(IV) in natural water

Polytetrafluoroethylene (PTFE) fiber was demonstrated as a new sorbent for flow injection on-line sorption preconcentration of trace elements. The on-line PTFE fiber packed microcolumn preconcentration system was coupled with hydride generation atomic fluorescence spectrometry (HG-AFS) for the determination of (ultra)trace selenite (Se(IV)) in natural water. Selective determination of Se(IV) in aqueous solution was achieved by on-line formation of Se(IV)–pyrrolidinedithiocarbamate (PDC) complex over a wide sample acidity range of 0.01–50% v/v HCl, its sorption onto the surface of the PTFE fiber in the microcolumn, elution with 3% m/v KBH4 in 0.5% m/v KOH, hydride generation with 15% v/v HCl solution and determination with atomic fluorescence spectrometry. The alkaline KBH4 solution was employed not only as an efficient eluent but also as the reductant to produce selenide anion for subsequent hydride generation. With a consumption of 12.4 ml of sample solution, a detection limit (3σ) of 4 ng l−1 was achieved at a sample throughput of 26 samples h−1. The retention efficiency was 67%, being five times that obtained with a PTFE knotted reactor (KR). The linear ranges of the diagrams of signal intensity against sample loading flow rate, and sample loading time, were much wider than those achieved with a KR, offering more potential for obtaining high sensitivity by increasing sample loading rates and/or sample loading time. The precision for 11 replicate measurements of 0.5 µg l−1 Se(IV) was 1.5% (RSD). The recoveries of Se(IV) from natural water samples varied from 96 to 108%. The concentration of Se(IV) in a certified reference material (NASS-5, sea-water) determined by the present method with a simple aqueous standard curve calibration was in good agreement with the certified value. The developed method was also successfully applied to the detection of Se(IV) in local river water, lake water and sea-water samples.

Automated on-line separation–preconcentration system for platinum determination by electrothermal atomic absorption spectrometry

A flow injection on-line sorption preconcentration system for the electrothermal atomic absorption spectrometric determination of platinum has been developed. The method employs on-line preconcentration of platinum on a column packed with silica gel functionalised with 1,5-bis(di-2-pyridyl)methylene thiocarbohydrazide (DPTH-gel) placed in the autosampler arm. The modification of the autosampler in the tubing line and circuit allowed either the flow of the sample through the column or the operation of the autosampler in the normal mode, where microlitres of 2 M HNO 3, which acts as the elution agent, pass through the microcolumn eluting Pt(IV), which is directly deposited in the graphite tube as a drop of a precisely defined volume. An enrichment factor of 41.7 and a 3 σ detection limit of 0.8 ng ml −1 along with a sampling frequency of 29 h −1 are achieved with 60 s preconcentration time at a sample flow rate of 2.4 ml min −1. The relative standard deviation is 1.6% for 4 ng ml −1 Pt ( n=11). The method has been applied to the determination of platinum in catalyst, vegetation, soil and water samples.

Flow injection on-line preconcentration of low levels of Cr(VI) with detection by ETAAS: Comparison of using an open tubular PTFE knotted reactor and a column reactor packed with PTFE beads

A flow injection (FI) on-line sorption preconcentration procedure utilizing a packed column reactor and combined with electrothermal atomic absorption spectrometry (ETAAS) is proposed for the determination of low levels of Cr(VI) in water samples. Polytetrafluoroethylene (PTFE) beads packed in a mini-column is used as sorbent material. The complex formed between Cr(VI) and ammonium pyrrolidine dithiocarbamate (APDC) is sorbed on the PTFE beads, and is subsequently eluted by an air-monosegmented discrete zone of absolute ethanol (35 μl), the analyte being quantified by ETAAS. The preconcentration procedure using the proposed column significantly enhances the preconcentration efficiency as compared with the preconcentration approach incorporating an open tubular PTFE knotted reactor (KR). Comparing the two procedure for equal surface sorption area, the advantages of using a packed column are observed in terms of limit of detection, enrichment factor and retention efficiency. With a preconcentration time of 60 s, and a sample flow rate of 5.0 ml l −1, the enrichment factor (30.1) and the retention efficiency (24.1%) were doubled, yielding a detection limit (3 σ) as low as 8.8 ng l −1. The sample frequency was 16.7 h −1. The concentration efficiency was 8.38 and the precision was 1.05% at 0.5 μg l −1 of Cr(VI). The proposed column has been applied successfully to the analysis of natural water and synthetic seawater. Its performance was verified by the analysis of two certified Cr(VI)-reference materials and by recovery measurements on spiked samples.

Flow injection on-line sorption preconcentration coupled with hydride generation atomic fluorescence spectrometry for determination of (ultra)trace amounts of arsenic(III) and arsenic(V) in natural water samples.

A flow injection on-line sorption preconcentration and separation in a knotted reactor (KR) was coupled to hydride generation atomic fluorescence spectrometry (HG-AFS) for speciation of inorganic arsenic in natural water samples. The method involved on-line formation of the As(III)-pyrrolidinedithiocarbamate (PDC) complex over a sample acidity of 0.001-0.1 mol L(-1) HCl, its adsorption onto the inner walls of the KR made from 150-cm long x 0.5-mm i.d. PTFE tubing, elution withmol L(-1) HCl, and detection by HG-AFS. Total inorganic arsenic was determined after prereduction of As(V) to As(III) with 1% m/v L-cysteine. The concentration of As(V) was calculated by the difference of the total inorganic arsenic and As(III). A 1 mol L(-1) concentration of HCl was employed not only as the efficient eluent but also as the required medium for subsequent hydride generation. Potential factors that affect adsorption, rinsing, elution, and hydride generation were investigated in detail. The low cost, easy operation, and high sensitivity are the obvious advantages of the present system. With consumption of a 6 mL sample solution, an enhancement factor of 11 and a detection limit (3s) of 0.023 microg L(-1) As(III) were obtained at a sample throughput of 32 h(-1). The precision for 14 replicate measurements of 1 microg L(-1) As(III) was 1.3% (RSD). The recoveries from natural water samples varied from 96.7 to 105% for 2 microg L(-1) of As(III) spike and from 97.1 to 107% for 2 microg L(-1) of As(V) spike. The analytical results obtained by the present method for total arsenic in the certified reference materials, SLRS-4 (river water) and NASS-5 (seawater), agreed well with the certified values. The developed method was also successfully applied to the speciation of inorganic arsenic in local natural water samples.

Determination of sub-parts-per-trillion levels of rare earth elements in natural waters by inductively coupled plasma time-of-flight mass spectrometry after flow injection on-line sorption preconcentration in a knotted reactor

A flow injection (FI) on-line sorption system, for the preconcentration and separation in a knotted reactor (KR), is coupled with inductively coupled plasma time-of-flight mass spectrometry (ICP-TOFMS) for the fast, selective and sensitive determination of ultra-trace concentrations of rare earth elements (REEs) in environmental waters. The on-line preconcentration and separation of the REEs is achieved by sorption of the REE complexes formed in the pH range 3.7–4.6 on the inner walls of a (300 cm × 0.5 mm) PTFE KR pre-coated with the chelating reagent 1-phenyl-3-methyl-4-benzoylpyrazol-5-one (PMBP) at a pH of 9.6. The analytes are eluted and transported to the ICP-TOFMS system with 2% (v/v) HNO3 containing 0.5 µg l−1 of Rh and In as internal standards, using ultrasonic nebulisation. The REEs are effectively preconcentrated and separated from the major matrix constituents—alkali and alkaline earth elements. Of particular significance is their separation from barium, which produces considerable isobaric interferences on some of the analytes. Using a preconcentration time of 30 s and a sample flow rate of 4.4 ml min−1, enhancement factors of 15 to 22 for the different REES are achieved. The detection limits (3σ) range from 3 to 40 pg l−1. The precision for 9 replicate determinations of 0.1 µg l−1 of each analyte is better than 5% (RSD). The accuracy of the method is demonstrated by the analysis of environmental waters and by recovery measurements on spiked samples.

Ultratrace determination of cobalt in natural waters by electrothermal atomic absorption spectrometry using flow-injection on-line sorption preconcentration in a knotted reactor precoated with 1-phenyl-3-methyl-benzoylpyrazol-5-one

A fully automated procedure was developed for the ultratrace determination of cobalt in natural waters by on-line flow injection (FI) sorption preconcentration of metal chelate complexes on the walls of a PTFE knotted reactor precoated with a chelating reagent, coupled with electrothermal atomic absorption spectrometry (ETAAS). Ammonium pyrrolidinedithiocarbamate (APDC), 8-hydroxyquinoline (HQ), 1-phenyl-3-methyl-4-benzoylpyrazol-5-one (PMBP) and 2-nitroso-1-naphthol-4-sulfonic acid (NNA) were compared as chelating reagents for this system. PMBP offered the best performance characteristics for the preconcentration of Co. An enhancement factor of 28 and a detection limit (3σ) of 8.1 ng l−1 are achieved with 120 s preconcentration time at a sample flow rate of 1.2 ml min−1. The precision (RSD) is 2.1% for 0.2 µg l−1 Co. The interference caused by Al(III) was overcome by the use of fluoride as a masking agent while the interferences from Cu, Fe(II) and Fe(III) were masked by thiourea. The accuracy of the method was demonstrated by the analysis of certified reference materials and recovery measurements on spiked samples.

Flow injection on-line sorption preconcentration of trace amounts of copper and manganese in a knotted reactor precoated with 1-phenyl-3-methyl-4-benzoylpyrazol-5-one coupled with electrothermal atomic absorption spectrometry

K. Benkhedda, E. Ivanova and F. Adams, J. Anal. At. Spectrom., 1999, 14, 957 DOI: 10.1039/A900630C

Determination of (ultra)trace amounts of arsenic(III) and arsenic(V) in water by inductively coupled plasma mass spectrometry coupled with flow injection on-line sorption preconcentration and separation in a knotted reactor.

A method has been developed for determination of (ultra)trace amounts of As(III) and As(V) in water by flow injection on-line sorption preconcentration and separation coupled with inductively coupled plasma mass spectrometry (ICPMS) using a knotted reactor (KR). The determination of As(III) was achieved by selective formation of the As(III)-pyrrolidine dithiocarbamate complex over a sample acidity range of 0.01-0.7 mol L-1 HNO3, its adsorption onto the inner walls of the KR made from 150-cm-long, 0.5-mm-i.d. PTFE tubing, elution with 1 mol L-1 HNO3, and detection by ICPMS. Total inorganic arsenic was determined after prereduction of As(V) to As(III) in a 1% (m/v) L-cysteine-0.03 mol L-1 HNO3 media. The concentration of As(V) was calculated by difference (the total inorganic arsenic and As(III)). Owing to the group-specific character of the chelating agent, and the use of an efficient rinsing step before elution, the interferences encountered in conventional ICPMS from common major matrix, alkali and alkaline earth metals, and chlorides were eliminated. The presence of organoarsenic species such as monomethylarsonate and dimethylarsinate in water samples had no effect on the results of As(III) and As(V). Thus, the method can be applied to the speciation analysis of inorganic arsenic at submicrogram per liter levels in aqueous solutions with high total content of dissolved solid and/or high content of chlorides. Using a preconcentration time of 60 s and a sample flow rate of 5 mL min-1, an enhancement factor of 22 was achieved in comparison with conventional ICPMS. The time required for a single determination was 200 s. The detection limits (3s) was evaluated to be 0.021 microgram L-1 for As(III) and 0.029 microgram L-1 for total inorganic arsenic. The precision for 14 replicate determinations of 1 microgram L-1 As(III) was 2.8% (RSD) with drift correction and 3.9% (RSD) without drift correction. The concentrations of As(III) and As(V) in synthetic mixtures obtained by the present method were in good agreement with expected values. Results obtained by the proposed method for total arsenic in a river water reference material agreed well with certified and recently reevaluated values. The method was also applied to the speciation analysis of inorganic arsenic in porewaters.

Flow injection on-line sorption preconcentration of platinum in a knotted reactor coupled with electrothermal atomic absorption spectrometry

A flow injection on-line sorption preconcentration method for the electrothermal AAS determination of platinum has been developed. The pyrrolidine dithiocarbamate complexes of either Pt4+ or Pt2+, formed in 0.7 mol L–1 HNO3, are on-line adsorbed on the inner walls of a PTFE knotted reactor and subsequently eluted with methanol. An enhancement factor of 112 and a detection limit (3 σ) of 10 ng L–1 along with a sampling frequency of 21 h–1 are achieved with a 90 s preconcentration time at a sample flow rate of 8.8 mL min–1. The relative standard deviation is 2.5% for 0.4 μg L–1 Pt. The method has been applied to the determination of platinum in blood samples.

Electrothermal atomic absorption spectrometric determination of cadmium and lead in blood using flow injection on-line sorption preconcentration in a knotted reactor

A flow injection on-line sorption separation system combining a knotted reactor (KR) and two sorbent extraction columns was developed for the electrothermal atomic absorption spectrometric determination of (ultra) trace amounts of cadmium and lead in freeze-dried blood samples. The diethyldithiophosphate complexes of the analytes were selectively adsorbed on the inner walls of the PTFE KR. The chelating reagent was on-line purified using conical sorbent extraction columns packed with 20 mg of C 18 bonded silica gel. The collected analyte complexes were quantitatively eluted from the 100 cm KR with 35 μl of methanol and the eluate was directly introduced into a pyrolytically coated graphite tube pre-treated with iridium modifier. Enhancement factors of 26 and 99 and detection limits of 0.2 and 1.6 ng l −1 were obtained for cadmium and lead, respectively. The relative standard deviation was 2.1% for 0.02 μg l −1 cadmium and 2.7% for 0.2 μg l −1 lead. The spike recovery was between 90 and 100%. The results from the analysis of biological reference materials agreed with the certified or indicated values.

Determination of copper, manganese and nickel in biological samples and sea-water by flow injection on-line sorption preconcentration in a knotted reactor coupled with electrothermal atomic absorption spectrometry

A flow injection system with on-line sorption preconcentration of copper, nickel and manganese with ammonium pyrrolidinedithiocarbamate (APDC) or 8-hydroxyquinoline (HQ) in a knotted reactor (KR) coupled with electrothermal atomic absorption spectrometry was developed. APDC offered better performance characteristics than HQ for the preconcentration of copper and nickel but could not be employed for manganese. The performance characteristics of the determination of copper and nickel with APDC were: detection limits (3σ), 6.0 and 7.6 ng l–1, precision (RSD) 2.5% for 0.2 µg l–1 and 1.5% for 0.2 µg l–1 and enhancement factors 44 and 21 using a 30 s preconcentration time. The corresponding parameters for the determination of manganese with HQ were detection limit 29.0 ng l–1, precision (RSD) 2.9% for 0.4 µg–1 manganese and enhancement factor 8 with a 30 s preconcentration time. The sampling frequency was 26 h–1. The accuracy of the method was demonstrated by the analysis of certified reference materials and by recovery measurements on spiked samples.

Determination of bismuth in cod muscle, lake and river sediment by flow injection on-line sorption preconcentration in a knotted reactor coupled with electrothermal atomic absorption spectrometry

A selective and robust flow injection (FI) on-line sorption separation and preconcentration procedure was developed for the determination of bismuth in cod muscle, lake and river sediment samples by electrothermal atomic absorption spectrometry (ETAAS). The diethyldithiophosphate complex of bismuth is formed in 0.5–4% (v/v) HNO 3 and adsorbed onto the inner walls of a PTFE knotted reactor. The complex is eluted with 30% (v/v) HCl and the eluate is directly introduced into a pyrolytically coated graphite tube without a preheating step. The ETAAS determination of the concentrated analyte is carried out in parallel with the next preconcentration cycle. An enhancement factor of 74 and a detection limit (3 σ) of 3 ng l −1 along with a sampling frequency of 28 h −1 were achieved with a 60 s loading time at a sample flow rate of 5.2 ml min −1. The relative standard deviation was 3.4% for 0.1 μg l −1 ( n=9). The analytical results for the Community Bureau of Reference (BCR) CRMs 280 (lake sediment) and 320 (river sediment) were in good agreement with the indicative values for the bismuth content. For the BCR CRM 422 (cod muscle) a value of 14 ng g −1 was found.

Determination of Thallium in River Sediment by Flow Injection On-line Sorption Preconcentration in a Knotted Reactor Coupled With Electrothermal Atomic Absorption Spectrometry

Download options Please wait... Article information DOI https://doi.org/10.1039/A608539C Article type Paper Download Citation Analyst, 1997,122, 667-671 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Determination of Thallium in River Sediment by Flow Injection On-line Sorption Preconcentration in a Knotted Reactor Coupled With Electrothermal Atomic Absorption Spectrometry E. Ivanova, X. Yan, W. van Mol and F. Adams, Analyst, 1997, 122, 667 DOI: 10.1039/A608539C To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author Elissaveta Ivanova Xiu-Ping Yan Willy van Mol Freddy Adams

Flow Injection On-line Sorption Separation and Preconcentration With a Knotted Reactor for Electrothermal Atomic Absorption Spectrometric Determination of Lead in Biological and Environmental Samples

X. YAN and F. ADAMS, J. Anal. At. Spectrom., 1997, 12, 459 DOI: 10.1039/A607430H

Flow-injection on-line sorption preconcentration in a knotted reactor for electrothermal atomic absorption spectrometric determination of ultratrace amounts of cobalt in natural waters

A flow-injection on-line sorption preconcentration–electrothermal atomic absorption spectrometric (ETAAS) method has been developed for the determination of ultratrace amounts of cobalt in natural waters. The preconcentration 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 μL 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 preconcentration of the next sample. With a sample consumption of 6.7 mL, an enhancement factor of 47 in comparison with direct injection of 45 μL aqueous solution was obtained at a sampling frequency of 31 h−1. The detection limit (3 σ) was found to be 2.8 ng L−1. The precision was 3% relative standard deviation (RSD) at the 0.2 μg 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. © 1997 John Wiley & Sons, Inc. Lab Robotics and Automation 9: 191–199, 1997.