Direct Determination Of Arsenic Research Articles

Direct determination of arsenic in soil samples by fast pyrolysis–chemical vapor generation using sodium formate as a reductant followed by nondispersive atomic fluorescence spectrometry

This new study shows for the first time that sodium formate can react with trace arsenic to form volatile species via fast pyrolysis – chemical vapor generation. We found that the presence of thiourea greatly enhanced the generation efficiency and eliminated the interference of copper. We studied the reaction temperature, the volume of sodium formate, the reaction acidity, and the carried argon rate using nondispersive atomic fluorescence spectrometry. Under optimal conditions of T=500°C, the volumes of 30% sodium formate and 10% thiourea were 0.2ml and 0.05ml, respectively. The carrier argon rate was 300mlmin−1 and the detection limit and precision of arsenic were 0.39ng and 3.25%, respectively. The amount of arsenic in soil can be directly determined by adding trace amount of hydrochloric acid as a decomposition reagent without any sample pretreatment. The method was successfully applied to determine trace amount of arsenic in two soil-certified reference materials (GBW07453 and GBW07450), and the results were found to be in agreement with certified reference values.

Direct Determination of Arsenic in Beet Sugar Molasses Using Nickel as Chemical Modifier by Electrothermal Atomic Absorption Spectrommetry

AbstractA simple electrothermal atomic absorption spectrometric (ETAAS) method is described for direct determination of arsenic in sugar beet molasses samples. Pyrolytic graphite tubes were used as atomizers. The compression between modifiers such as nickel nitrate, palladium nitrate and the mixture of palladium and magnesium nitrate were performed and nickel nitrate selected as the best chemical modifier. The effects of pyrolysis and atomization temperature were also studied and the pyrolysis temperature of 900 °C and atomization temperature of 2300 °C have been chosen for temperature program. The detection limit of the method was 1 ng/mL As in sugar beet molasses samples. The relative standard deviation for ten determination of a spiked sample with concentration of 50 ng/mL As was 2.4%. The accuracy of the method was confirmed by the analysis of spiked samples. The linear rang of calibration is in the range of 1‐100 ng/mL of arsenic.

Direct determination of arsenic in petroleum derivatives by graphite furnace atomic absorption spectrometry: A comparison between filter and platform atomizers

In the present work a direct method for the determination of arsenic in petroleum derivatives has been developed, comparing the performance of a commercial transversely heated platform atomizer (THPA) with that of a transversely heated filter atomizer (THFA). The THFA results in a reduction of background absorption and an improved sensitivity as has been reported earlier for this atomizer. The mixture of 0.1% (m/v) Pd + 0.03% (m/v) Mg + 0.05% (v/v) Triton X-100 was used as the chemical modifier for both atomizers. The samples (naphtha, gasoline and petroleum condensate) were stabilized in the form of a three-component solution (detergentless microemulsion) with the sample, propan-1-ol and 0.1% (v/v) HNO 3 in a ratio of 3.0:6.4:0.6. The characteristic mass of 13 pg found in the THFA was about a factor of two better than that of 28 pg obtained with the THPA; however, the limits of detection (LOD) and quantification (LOQ) were essentially the same for both atomizers (1.9 and 6.2 μg L −1, respectively, for THPA, and 1.8 and 5.9 μg L −1, respectively, for THFA) due to the increased noise observed with the THFA. A possible explanation for that is a partial blockage of the radiation from the hollow cathode lamp by the narrow inner diameter of this tube and the associated loss of radiation energy. Due to the lack of an appropriate certified reference material, recovery tests were carried out with inorganic and organic arsenic standards and the results were between 89% and 111%. The only advantage of the THFA found in this work was a reduction of the total analysis time by about 20% due to the ‘hot injection’ that could be realized with this furnace. The arsenic concentrations varied from < LOQ to 43.3 μg L −1 in the samples analyzed in this work.

Feasibility of the internal standardization in direct determination of arsenic in wine samples by inductively coupled plasma atomic emission spectrometry

In this study, a fast and simple method is proposed for determination of arsenic in wine employing inductively coupled plasma atomic emission spectroscopy and internal standard technique. First Co, Bi, V and Y were evaluated as internal standards to minimize transport interferences. All samples and reference solutions were automatically spiked by autosampler, eliminating the need for manual dilutions. The result demonstrated that vanadium can be used as an internal standard. The experimental parameters (plasma power and nebulization flow rate) were optimized. The relative standard deviations (R.S.D) of measurements varied from 1.1 to 6.0% and 3.2 to 8.7% (n=12) with and without internal standardization, respectively. Recoveries in the 95–103% range for As spiked samples were obtained.

Direct determination of arsenic in sea-water by reaction cell inductively coupled plasma mass spectrometry

A new procedure for the direct determination of total arsenic in sea-water has been developed. In order to remove the polyatomic interferences arising from the direct analysis of 15-fold diluted sea-water samples, the dynamic reaction cell (DRC) technique was applied. Different analytical strategies, such as reactive removal of the interfering species by ammonia, methane or hydrogen, as well as arsenic oxidation by oxygen or nitrogen protoxide, followed by detection of the AsO+ ion were explored. The use of DRC pressurized with ammonia, methane or hydrogen was not able to reduce the spectral interfering effects at m/z = 75. On the other hand, satisfactory results were obtained by using oxygen at 0.8 cm3 min−1 or nitrogen protoxide at 0.5 cm3 min−1 and detecting the analyte at m/z = 91. The relevant parameters, such as the reactive gas flow rate, the Mathieu stability parameters a and q of the DRC, and the rod offset voltages of both cell and mass analyzer quadrupole, were optimized for maximum ion transmission and selectivity. Following the optimization of the DRC conditions, a new analytical procedure for the direct determination of total arsenic concentration in sea-water was hence developed. The main analytical performance characteristics of the optimized method were evaluated, with special attention to the determination of the “procedural” and “field” blanks. A detection limit as low as 40 ng L−1 and instrumental precision of about 2% were achieved. The accuracy was verified by the analysis of certified reference materials (CRM) of sea-water (NASS-4, CASS-4) and estuarine water (SLEW-3). The analytical precision for replicated analyses of the CRMs ranged from 2.3% to 5.0% (n = 5). Finally, the developed procedure was applied to a number of sea-water samples from the Ross Sea (Southern Ocean, Antarctica). Arsenic concentration ranged from 0.88 to 1.03 μg L−1 (n = 12), which are typical values for the uncontaminated offshore waters.

Direct determination of arsenic in beer by electrothermal atomic absorption spectrometry with deuterium background correction (D 2-ET-AAS)

We describe here a method for the direct determination of As in beer by D 2-ET-AAS, using Pd modifier, the atomization from platform and insertion of a cooling step before atomization. This method results in a 40% increase of sensitivity in peak-height measurements. Pd was found to be the most advantageous chemical modifier for the elimination of phosphate interference compared to Ni or Pt + citric acid. In addition, Pd is able to stabilize As at charring temperatures of 1500 °C and further addition of V, Mg or Sr have no influence. Addition of the modifier to standards and samples made possible the use of matrix-free standard solutions for attaining accurate analysis of diluted samples. The accuracy was checked by the comparison of results of direct analysis of beer samples by the proposed method with those found for microwave-digested samples measured by an inductively coupled plasma orthogonal acceleration time-of-flight mass spectrometer (ICP- oa-TOFMS) method. The accuracy was also confirmed by the analysis of certified reference samples.

Determination of arsenic in peat samples using HG-AFS and l-cysteine as pre-reductant

An accurate, sensitive, and robust analytical procedure for the direct determination of arsenic (As) in nitric acid digests of peat samples using hydride generation-atomic fluorescence spectrometry (HG-AFS) has been developed. Existing HG-AFS procedures developed for other environmental matrices employing potassium iodide (KI) as pre-reductant cannot be applied for the determination of As in peat samples, because they largely underestimate the actual As concentration. Here, the pre-reduction capabilities of KI and L-cysteine in nitric acid digests of peat and plant samples were tested systematically, revealing that only L-cysteine (12.8 g l−1) provided accurate results for peat samples. The newly developed analytical procedure was successfully applied to the determination of As in several peat samples and peat reference materials with concentrations ranging from ∼100 ng g−1 to ∼10000 ng g−1, as well as certified environmental reference materials yielding good agreement between found and certified values. The LOD of 4 ng l−1 and the precision of <3% for peat samples allowed the reliable quantification of As in all investigated peat samples. Results for As in selected peat samples obtained using the new HG-AFS procedure were confirmed in-house using ICP-SF-MS and HG-AAS.

Direct determination of arsenic in acid digests of plant and peat samples using HG-AAS and ICP-SF-MS

A new analytical procedure for the reliable and direct determination of arsenic (As) in nitric acid digests of ombrotrophic peat samples in the low ng l −1 range has been developed based on hydride generation-atomic absorption spectrometry (HG-AAS). The pre-reduction capabilities of KI/ascorbic acid and of l-cysteine in nitric acid digests of peat and plant samples for the conversion of As(V) to As(III) were tested systematically. Samples were digested with high purity nitric acid in a high-pressure microwave autoclave at 240 °C and subsequently measured using HG-AAS or ICP-SF-MS (inductively coupled plasma-sector field-mass spectrometry). Using KI/ascorbic acid as pre-reductant, the accuracy and precision were poor when digests of complex matrices, such as peat were analyzed for As by HG-AAS. However, 10 g l −1 l-cysteine was successfully employed as pre-reductant in diluted nitric acid digests (∼3%, v/v) of peat samples prior to hydride generation of As with 0.5% (m/v) of NaBH 4 and 7 mol l −1 HCl. The analytical procedure was critically evaluated by analyzing several certified plant reference materials, two in-house peat reference materials and by the determination of As in diluted digests of peat samples with ICP-SF-MS. The results for the determination of As in various peat and plant materials showed excellent agreement with the reference values. The method detection limits for the determination of As by the optimized HG-AAS procedure and by ICP-SF-MS were 23 ng g −1 and 1.4 ng g −1 in solid peat, respectively. The newly developed analytical procedure was applied to the determination of As in selected peat samples. Results for As in these peat samples obtained by the developed HG-AAS procedure and the optimized procedure for the determination of As with ICP-SF-MS were highly correlated ( R 2 = 0.993, n = 12).

Direct determination of arsenic in sea water by electrothermal atomization atomic absorption spectrometry using D2 and Zeeman background correction

Arsenic in sea water was determined directly by graphite furnace atomic absorption spectrometry (GFAAS) using palladium nitrate as chemical modifier, at an optimum concentration of 15 mg l−1. Deuterium and Zeeman effect background correction were compared and gave detection limits of 0.6 and 0.8 μg l−1, respectively. Precisions between 8 and 2%, for both correctors, were obtained with an injection volume of 40 μl. The accuracy obtained with different reference materials: CRM-403 (1.461 μg kg−1), NASS-4 (1.26 ±0.09 μgl−1) and IAEA/W-4 (24–31 μg l−1) was studied for large injection volumes for both background correction systems. Interferences by chloride, sodium, potassium, calcium and silicon were removed by Zeeman correction, whereas deuterium correction was much less effective and was insufficiently accurate for sea water samples.

Minimization of phosphate interference in the direct determination of arsenic in urine by electrothermal atomic absorption spectrometry

A direct method for the determination of arsenic in urine by Zeeman atomic absorption spectrometry has been proposed by graphite furnace atomization with (NH 4) 3RhCl 6 + citric acid as a mixed matrix modifier. Different matrix modifiers including palladium, nickel and rhodium, were used for the elimination of phosphate interference, which was most troublesome in the arsenic determination in urine. Rhodium was preferred to palladium and nickel; in its presence the determination of arsenic in urine can tolerate a char temperature of 1600 °C, a temperature high enough to drive off the urine matrix including calcium phosphate without losing arsenic. The citric acid in the furnace evolved active gases and carbon upon decomposition thus facilitating the creation of a favorable reducing environment for the formation of a Rh-As alloy or intermetallic compounds which stabilized arsenic to a high temperature. In the determination of 1 ng of arsenic, 1.0 mg ml −1 phosphate in the form of calcium phosphate can be tolerated. Analytical results obtained for standard urine sample compared (>92% recovery) well with the certified value. The lowest concentration of arsenic that could be determined was 20 ng ml −1 in the undiluted urine.

Direct determination of arsenic, cadmium, lead and zinc in soils and sediments by electrothermal vaporization and inductively coupled plasma excitation spectrometry

The direct determination of volatile heavy metals (As, Cd, Pb and Zn) in soil and sediment samples by electrothermal vaporization and inductively coupled plasma excitation atomic emission spectrometry (ETV-ICP-AES) has been demonstrated. By addition of toluene vapour to the internal furnace gas and sodium selenite to both solution standards and solid samples the transport losses of analytes were considerably reduced. Three calibration methods, based on solution standards, addition of standard solutions to powder sample and variable mass of solid certified reference material have been investigated, and no characteristic difference was found in their performance. The relative deviations from the certified concentrations range between −13 and +15% (most often less than 7%), depending on the analyte. The background equivalent concentration data were about 20-fold better for the solid sampling ETV than for the dissolution based pneumatic nebulization sample introduction method.

Direct determination of arsenic in shale oil and its products by furnace atomic absorption spectrometry with a tetrahydrofuran solvent system

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDirect determination of arsenic in shale oil and its products by furnace atomic absorption spectrometry with a tetrahydrofuran solvent systemJoseph L. FabecCite this: Anal. Chem. 1982, 54, 13, 2170–2174Publication Date (Print):November 1, 1982Publication History Published online1 May 2002Published inissue 1 November 1982https://doi.org/10.1021/ac00250a009RIGHTS & PERMISSIONSArticle Views60Altmetric-Citations6LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (627 KB) Get e-Alerts Get e-Alerts

Application de la SAA électrothermique a Panalyse des matrices complexes: cas de l'arsenic dans les végétaux

This work shows the possibilities and the analytical limitations of ETA-SAA for arsenic determination in plants. Wet oxidation of these media is quantitative, but the direct determination of arsenic is strongly interferred with the presence of sulphuric acid and, principally, phosphorus, which is contained in plant matrix. In this case, only arsenic concentrations around 100 ng ml −1 in solution (5 μg g −1 in dry matter) can be directly determined. Because lower concentrations must be determined in unpolluted samples, two extraction procedures have been developed, both based on a preliminary reduction of As 5+ to As 3+ and a further extraction in toluene. NH 4I turns out as a better reducing agent than KI. In routine analysis, arsenic concentrations in the vicinity of 20ng g −1 in dry matter can be easily determined under the adopted conditions.

Direct determination of arsenic in coal by atomic-absorption spectroscopy using solid sampling and electrothermal atomisation

A method using graphite furnace atomic-absorption spectroscopy for the determination of arsenic in coal is described. The analysis may be performed on either a solution of coal or, preferably, by direct atomisation of a slurry of powdered coal. Dissolution of coal is brought about using a mixture of nitric acid, hydrofluoric acid and hydrogen peroxide. Both procedures require matrices of nickel nitrate (volatilisation suppressant) and magnesium nitrate (ashing aid). The arsenic contents of a selection of coals determined by the solution method were in good agreement with certified values and results obtained by other analytical procedures. The solid-sampling technique gave the best results when powdered coal standards of known arsenic content were used for calibration. The analytical characteristics of the method compare favourably with the existing British Standard method, which was shown to give low recoveries for certain coals. The over-all analysis time for the proposed slurry technique is 10 min and the detection limit is less than 0.1 µg g–1.

Direct determination of arsenic in urine by differential pulse anodic stripping voltammetry

Various parameters affecting the behaviour of arsenic in differential pulse anodic stripping voltammetry (Dpasv) have been studied, such as the electrodeposition potential, working electrode, electrolysis time and the nature of the electrolyte solution. It was found that under suitable conditions arsenic(III) can be determined directly in diluted urine byDpasv. For the quantitative determination of arsenic(III) in urine calibration curves were recorded and recovery experiments have been carried out. A detection limit of 20Μg As/l has been found and in the concentration range of 0.3–1.0 mg/l the coefficient of variation was better than 5%.

The determination of arsenic by electrothermal atomic absorption spectrometry with a graphite furnace : Part 1. Difficulties in the direct determination

The direct determination of arsenic by graphite-furnace atomic absorption spectrometry is critically examined. Matrix stabilization by nickel salts is effective for preventing charring losses of arsenic, but cannot eliminate strong interferences. Direct analysis of environmental and biological samples is impossible because of the presence of aluminium, sodium, potassium and sulphates.