Biological monitoring of arsenic in semiconductor workers

In the manufacture of integrated circuits involving semiconductors, various hazardous materials including arsenic compounds are used. This paper present an evaluation of the biological monitoring of arsenic in the urine, blood and hair of semiconductor workers. Eighty-two blood samples were obtained from research and development workers in a semiconductor factory. Thirty-one samples of urine were obtained from the same group of worker before and after a work period (one shift). Seventy-three hair samples were similarly obtained from the workers. The concentration of arsenic in each sample was determined by arsine (AsH₃) generation flame atomic absorption spectrometry after wet ashing of the sample. The mean concentration of arsenic in hair in these semiconductor workers was significantly higher than that of controls. The mean concentration of arsenic in hair from workers with a longer employment duration was higher than from those with a shorter employment duration. The mean concentration of arsenic in hair from workers engaged in epitaxial growth processes was higher than from workers engaged in other processes. The concentrations of arsenic in hair from semiconductor workers correlated with the duration of their employment. The mean concentration of arsenic in urine before a work a period (shift) was not significantly different from that of controls. The mean concentration of arsenic in urine after a work period was in fact lower than that of controls. The mean concentration of arsenic in blood was not significantly different from that of controls. The determination of arsenic in hair is therefore considered useful for the evaluation of relatively long-term exposure to arsenic in semiconductor workers.     

Arsenic determination in certifiable color additives by dry ashing followed by hydride generation atomic absorption spectrometry

The preparations of digested samples of certifiable color additives by dry ashing and wet digestion for arsenic analysis by hydride generation atomic absorption spectrometry (AAS) were compared. The dry ashing technique was based on the preparation used in ASTM D4606-86 for determination of As and Se in coal. The acid digestion method used nitric and sulfuric acids heated by microwaves in sealed vessels. The digested color additives were analyzed for As by using hydride generated from sodium borohydride mixed with the acidified solution on a flow injection system leading to an atomic absorption spectrometer. Dry ashing was preferable to wet digestion because wet digestion yielded poor recoveries of added As. Dry ashing followed by hydride generation AAS gave determination limits of 0.5 ppm As in the color additives. At a specification level of 3 ppm As, the precision of the method using dry ashing was +/- 0.4 ppm (95% confidence interval).     

Bestimmung von Arsen in biologischem Material mittels Atomabsorptionsspektralphotometrie

A modified determination of arsenic by means of AAS is described. AsH₃ generation is carried out in a reaction vessel by addition of NaBH₄. The gas evolved is swept into a nitrogen entrained air flame. The detection limit amounts to 10 ng of arsenic.In the dry ashing step used for biological materials Mg(NO₃)₂ is used as an ashing aid. It was found, that an excess of four times of Mg(NO₃)₂ is necessary for finding all arsenic present. An ashing temperature of 500° C is suitable. 2 h of ashing time is enough if the samples are carefully preashed. Various foods have been analysed, mainly all higher burdened species. Arsenic contents in drinking water and some detergents have also been investigated.     

A Study of Two Atomic Absorption Methods for the Determination of Sub-Microgram Amounts of Arsenic and Selenium

Abstract

Two atomic absorption accessory units were studied for the determination of arsenic and selenium in waters. One involves a flame mode while the other a flameless mode. Each was analyzed for requirements in speed per analyses, sample sizes required, potential interferences, coefficients of variation, and in overall ease in use.

Although the flameless mode could determine lower levels of arsenic and selenium than the flame mode, it was hampered by some severe interferences. Advantages of these accessories in their use over conventional wet chemical methods included: speed per analysis, elimination of time-consuming concentration steps, and elimination of using fragile equipment and noxious solvents.     

Dosage des Traces d'Arsenic par Voltametrie et Redissolution Cathodique dans les Solutions Industrielles de ZnSO4

Abstract

A method is described for the determination of traces of arsenic in industrial ZnSO₄ solutions for electrolysis by cathodic stripping voltammetry. The limit of detection is of the order of 1 ppb.     

Methylation of inorganic arsenic by arsenic-tolerant freshwater algae

Five arsenic-resistant freshwater algae which had been isolated from an arsenic-polluted environment were studied for the biotransformation of arsenic compounds accumulated by them from the aqueous phase. The algal cells bioaccumulating arsenic were digested by 2 mol dm^?3 NaOH at 95°C, the As? C bonds except for As? CH₃ were cleaved by the treatment and the methylated arsenic compounds were reduced to the corresponding arsines by sodium borohydride (hydride generation). The arsines were chromatographically separated on the basis of their boiling-point difference and determined by atomic absorption spectrophotometry. Methylated arsenic compounds were found in all algal cells. The predominant arsenic species in the cells, however, were non-methylated arsenic compounds which were mainly present in the residue of a chloroform–methanol extract. The non-methylated arsenic compounds were found to be not present in the free inorganic arsenic substrate and to be bound strongly with proteins or polysaccharides in the cells. Methylated arsenic compounds were found mainly in the lipid-soluble fractions and the major form was a dimethylarsenic compound. Trimethyl- and monomethyl-arsenic compounds were detected but at very low level. The dimethylarsinic acid was not present in the free form in the lipid-soluble fraction and should be bound with a lipid molecule. It was also found that the accumulation of arsenic by Nostoc occurred only in living cells.     

Determination of arsenic by inductively-coupled plasma atomic emission spectrometry enhanced by hydride generation from organized media

A method is described for the determination of arsenic, which combines a continuous flow hydride generation technique with an inductively coupled plasma atomic emission detection system. Some atomic absorption preliminary studies are described as well. Arsine is generated with NaBH(4) from a didodecyldimethylammonium bromide (DDBA) vesicular medium. The analytical performance of this vesicles-enhanced method is superior to the generation of the hydride from aqueous media: the detection limit (0.6 ppb) is improved by a factor of 2 and greater tolerance to interferences is observed for arsine generation from DDBA vesicles. Precision of As determinations is also improved. The proposed method has been validated for low As levels determinations in two Certified Reference Materials (CRM) sediments with satisfactory results. The potential of organized media to improve hydride generation is addressed.     

Determination of Inorganic and Total Arsenic in Wines by Hydride Generation Atomic Absorption Spectrometry

A method is described for the determination of inorganic arsenic species and total arsenic in wines by means of hydride generation atomic absorption spectrometry (HGAAS). Simple ethanol evaporation is the only pretreatment procedure proposed for wine samples prior to direct measurement of inorganic arsenic (AsIII) and As(V) species by HGAAS. The total arsenic content is determined after microwave digestion of the wine samples. The optimal parameters for the microwave digestion procedure and the next HGAAS measurement of arsenic are established. The detection limits achieved are 0.1µgL^–1 for inorganic and total arsenic determination. The relative standard deviation for both procedures and for ten independent determinations varied between 8 and 15% for arsenic species in the range of 1–30µgL^–1. The accuracy of the procedure for total arsenic determination was proved by comparative analysis using electrothermal atomic absorption spectrometry.     

Speciation of arsenic using capillary gas chromatography with atomic emission detection

A gas chromatography method with atomic emission detection (GC-AED) for the determination of dimethylarsinic acid (DMA), monomethylarsonic acid (MMA) and inorganic arsenic was optimized. The analytes were derivatized in the sample solutions with methyl thioglycolate (TGM) and the products were extracted into cyclohexane before an aliquot of this organic phase was directly injected into the chromatograph. The procedure was applied to the analysis of seawaters, wines, beers and infant foods, the last requiring an additional enzymatic reaction prior to analyte derivatization. Detection limits in seawaters and beverages were 0.05, 0.15 and 0.8 ng mL⁻¹ for DMA, MMA and inorganic arsenic, respectively. In infant foods the detection limits were 1, 10 and 25 ng g⁻¹ for DMA, MMA and inorganic arsenic, respectively. Inorganic arsenic was detected in some of the seawater samples and three of the wines analyzed at concentration levels in the range 1-40 ng mL⁻¹, and DMA in several of the infant foods in the range 20-80 ng g⁻¹. The method was validated by analyzing a certified reference material and by recovery studies. All the samples were also analyzed by hydride generation and atomic fluorescence spectrometry (HG-AFS), which provided data for the total arsenic content.     

INDIRECT ATOMIC ABSORPTION SPECTROMETRIC METHOD FOR THE DETERMINATION OF ARSENIC

Abstract

An indirect atomic absorption spectrometric method for arsenic has been developed on the basis of heteropoly chemistry. Molybdoarsenic acid is formed, extracted and stripped by a basic buffer solution. The resulting molybdate, which is equivalent to a specific amount of arsenic, is determined by atomic absorption spectrometry.     

Bioaccumulation and excretion of arsenic compounds by a marine unicellular alga,polyphysa peniculus

Polyphysa peniculus was grown in artificial seawater in the presence of arsenate, arsenite, monomethylarsonate and dimethylarsinic acid. The separation and identification of some of the arsenic species produced in the cells as well as in the growth medium were achieved by using hydride generation–gas chromatography–atomic absorption spectrometry methodology. Arsenite and dimethylarsinate were detected following incubation with arsenate. When the alga was treated with arsenite, dimethylarsinate was the major metabolite in the cells and in the growth medium; trace amounts of monomethylarsonate were also detected in the cells. With monomethylarsonate as a substrate, the metabolite is dimethylarsinate. Polyphysa peniculus did not metabolize dimethylarsinic acid when it was used as a substrate. Significant amounts of more complex arsenic species, such as arsenosungars, were not observed in the cells or medium on the evidence of flow injection–microwave digestion–hydride generation–atomic absorption spectrometry methodology. Transfer of the exposed cells to fresh medium caused release of most cell–associated arsenicals to the surrounding environment.     

Non-chromatographic screening procedure for arsenic speciation analysis in fish-based baby foods by using electrothermal atomic absorption spectrometry

A procedure for the speciation analysis of arsenic in fish-based baby foods is presented. Inorganic arsenic, methylarsonic acid (MA), dimethylarsinic acid (DMA) and arsenobetaine (AB) were determined by electrothermal atomic absorption spectrometry (ETAAS) using suspensions prepared in a 0.01 mol L⁻¹ tetramethylammonium hydroxide (TMAH) solution. Speciation is based on the use of three different chemically modified ETAAS atomizers to obtain the analytical signals. Using a palladium salt as the chemical modifier, the signal corresponding to the total arsenic concentration is obtained. When palladium is replaced by Ce(IV), the signal is solely due to inorganic arsenic (III and V) + MA. If no signal is obtained in this latter case, it is possible to distinguish between DMA and AB using a zirconium coated atomizer. The signal obtained in this way is due solely to DMA, and the concentration of AB can be obtained by the difference with the total arsenic content. Determinations by ETAAS require the use of the standard additions method. The limits of detection for the determination of AB, DMA and inorganic arsenic (+MA) are 15, 25 and 50 ng g⁻¹ expressed as arsenic, respectively. These detection limits are good enough for the procedure to be appropriate for the rapid determination of these compounds, avoiding extraction processes and/or chromatographic separations. Data for commercial samples, as well as for four standard reference materials, are given.     

虾粉中总砷测定方法的探讨

用氢化物原子荧光光度法测定虾粉中总砷含量时,对干法灰化、湿法消解、微波消解3种样品处理方法对虾粉中砷元素测定结果的影响进行了比较。通过试验确定了最佳消解条件。砷元素浓度在0~10μg/L的范围内与荧光强度呈线性关系,线性相关系数r=0.999 6,检出限为0.2μg/L。比对结果表明,干法灰化适合于测定虾粉中总砷的含量,湿法消解测定总砷的含量偏低,微波消解不适合测定虾粉中总砷的含量。采用干法灰化-氢化物原子荧光光度法测定虾粉中总砷含量,加标回收率为76.2%~106.0%。     

Decomposition of organoarsenic compounds by using a microwave oven and subsequent determination by flow injection-hydride generation-atomic absorption spectrometry

Environmentally important organoarsenicals such as arsenobetaine, arsenocholine and tetramethylarsonium ion do not form volatile hydrides under the commonly used analytical conditions on treatment with borohydride and it has been difficult to determine their concentrations without further derivatization. This paper describes a rapid method which completely decomposes and oxidizes these arsenicals to arsenate by using potassium persulphate and sodium hydroxide with the aid of microwave energy. The quantitative decomposition of these species permits their determination at low nanogram levels, by hydride generation atomic absorption spectromety (HG AA). A new hydride generator which has high efficiency and minimum dead volume and therefore is suitable for flow injection analysis (FIA) is also described. A system combining flow injection analysis, online microwave oven digestion, and hydride generation followed by atomic absorption measurement, is developed. This system is capable of performing analysis at a sample throughput of 100-120 per hour. Calibration curves were linear from 10 to 200 ng cm^?3 of arsenic and the detection limit was 5 ng cm^?3 for a 100-μ injection or 0.5 ng of arsenic. All ten organoarsenic compounds studied gave arsenate as the decomposition product, which was confirmed by using molybdenum blue photometric measurement.     

Inorganic and Organic Arsenic Speciation in Seawaters by IEC-HG-AAS

Abstract

Arsenic (III), arsenic (V), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) were separated by ion-exchange chromatography. The elution sequence was as follows: 1.5 M ammonia followed by 0.12 M hydrochloric acid yielding As(III) 1 M hydrochloric acid followed by water yielding first As(V) and then MMA. Detection was by hydride generation-atomic absorption spectrometry. No interference was noted from 13 metallic ions.

The method provides a good linearity, precision, accuracy, and sensitivity. It has been applied to the speciation of arsenic in seawaters from the North West coast of Spain (1200 Km).     

Determination of Bismuth in Geological Materials by Flow Injection Hydride Generation Atomic Absorption Spectrometry

Abstract

Flow injection analysis (FIA) has been applied to sample introduction in conjunction with automated hydride generation and AAS techniques for the determination of Bi in rock samples. The powdered rock sample is digested with a mixture of hydrofluoric, perchloric, and nitric acids. The evolved hydride is carried through to a heated quartz tube by a stream of argon, and the atomic absorption of Bi is measured at 223.2 nm.

Thiosemicarbazide and 1,10 - phenanthroline are used as masking agents to control interferences from Cu and Ni. The method permits the accurate determination of Bi in geological materials at levels as low as 10 ppb with an analysis rate of more than 50 digested samples per hour. Bi values on 13 international geological reference samples are reported.     

Ion-Exchange Method for Analysis of Four Arsenic Species and its Application to Tap Water Analysis

Abstract

Arsenic (III), arsenic (V), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) were separated by ion-exchange chromatography. The elution sequence was as follows: 1.5 M ammonia followed by 0.12 M hydrochloric acid yielding As(III); 1 M hydrochloric acid followed by water yielding first As(V) and then MMA. Detection was performed by hydride generation-atomic absorption spectrometry.

The possible interferences of 13 metallic ions have been studied and none of them was found to interfere.

The method provides good linearity, precision, accuracy, and sensitivity. It has been applied to the speciation of arsenic in tap water samples from North West of Spain (a region about 29500 Km²).     

Determination of Vanadium in Foods by Atomic Absorption Spectrophotometry

ABSTRACT

A simple and sensitive method for the determination of vanadium in foods was established by using atomic absorption spectrophotometry with graphite furnace atomization. The proposed method includes formation of a chelate-complex by reacting vanadium with pyrrolidine dithiocarbamate (PDCA), extracting the chelate with xylene and measurement of the extract by atomic absorption. The recoveries of added vanadium to various foods were 91.3 and 109.1%, within 7.9% of the coefficient variation. The sensitivity of this method is 10 - 50 times higher than previous methods with a detection limit of 0.01 μg/g.     

Analysis of Refuse. A Comparison of Sample Digestion Methods

Abstract

The sample is prepared by grinding, blending, and ashing. Dissolution of the ash is accomplished by a multistep acid digestion. The sample solution is analyzed by atomic absorption for eleven elements. A spectrophotometric analysis is used to determine titanium. The relative standard deviation (RSD) for all twelve elements ranged from 2.44 to 122%. Aluminum, copper, and lead analysis produced the high RSD values.     

Determination of total arsenic and arsenic (III) in phosphate fertilizers and phosphate rocks by HG-AAS after multivariate optimization based on Box-Behnken design

In the present paper, a procedure for the determination of total arsenic and arsenic (III) in phosphate fertilizers and phosphate rocks by slurry sampling (SS) with hydride generation atomic absorption spectrometry (HG-AAS) is proposed. Arsenic (III) is determinated directly and total arsenic is determinated after reduction reaction. The procedure was optimized for the flow rate of NaBH₄, NaBH₄ and hydrochloric acid concentrations using a full two-level factorial and also a Box-Behnken design. Slurry preparation with hydrochloric acid in an ultrasonic bath allowed the determination of arsenic (III) with limits of detection and quantification of 0.1 and 0.3 μg L⁻¹, respectively. The precision of results, expressed as relative standard deviation (RSD), was always lower than 3%. The accuracy of this method was confirmed by analysis of certified sediment reference materials, while the procedure also allows for calibration using aqueous external standards. This method (SS/HG-AAS) was used to determine total arsenic and arsenic (III) in two phosphate rock samples and two phosphate fertilizer samples. In these samples, total arsenic concentrations varied from 5.2 to 20.0 mg kg⁻¹, while As (III) concentrations varied from 2.1 to 5.5 mg kg⁻¹, in agreement with published values. All samples were also analyzed using acid digestion/HG-AAS. Both, a paired t-test and a linear regression model demonstrated no significant difference (95% CL) between the results obtained using these two sample preparation procedures.