Determination Of Trace Arsenic Research Articles

Ultrasensitive and Simultaneous Determination of Arsenic and Antimony in Clinical Samples by Atomic Fluorescence Spectrometry

The determination of trace elements in human fluids facilitates the identification of metabolic disorders and physiological abnormities in clinical diagnosis. Elemental concentrations in serum, urine, and saliva are often low and highly prone to contamination. Consequently, a simple and ultrasensitive detection technique is required. In this study, a method was developed for the simultaneous determination of trace arsenic and antimony in clinical samples by hydride generation atomic fluorescence spectrometry. The experimental parameters that affect the generation, delivery, and atomization of volatile arsenic and antimony hydrides were investigated. The limits of quantification were calculated to be 0.0037 nanogram per milliliter and 0.0070 nanogram per milliliter for arsenic and antimony, respectively. The method was successfully applied for the analysis of fortified human serum, urine, saliva, and certified reference materials. The results obtained by the reported method were not statistically different from the certified values at the 95 percent confidence level.

A new and sensitive method for the determination of trace arsenic using differential pulse polarography

A new and simple differential pulse polarographic method has been developed for the trace determination of arsenic. When selenite was added into solutions of some ions such as copper, lead, cadmium, zinc, and chromium, their differential pulse polarographic peak decreased. A new reduction peak appeared at a more positive potential than the ion present and it was always higher than the corresponding reduction peak of the ion. Thus, we made use of this interference for the trace determination of As(III). By the addition of selenite onto As(III), a new As−Se intermetallic compound peak was formed at about −0.35 V (pH at about 1.0–2.0). The trace arsenic concentration could be determined simply from this peak by the addition of standard arsenic into a polarographic cell. In the presence of large amounts of selenite, 2 × 10−7 mol/L As(III) could be determined from this peak precisely. With the newly established method, the limit of detection was 1 × 10−8 mol/L (S/N = 3). Among the most common cations and anions, only Cd−Se and Pb−Se intermetallic compound peaks had an overlap with the As−Se peak. This interference could be eliminated simply by the addition of EDTA. This method was applied successfully for the determination of arsenic in a digested beer sample.

ChemInform Abstract: Selective Determination of Trace Arsenic and Antimony Species in Natural Waters by Gas Chromatography with a Photoionization Detector.

Traces amounts of arsenic and antimony in water samples were determined by gas chromatography with a photoionization detector after liquidnitrogen cold trapping of their hydrides. The sample solution was treated with sodium hydroborate (NaBH4) under weak-acid conditions for arsenic(III) and antimony(III) determination, and under strong-acid conditions for arsenic(III+V) and antimony(III+V) determination. Large amounts of carbon dioxide (CO2) and water vapor obscured determination of arsine and stibine. Better separation from interference could be achieved by removing CO2 and water vapor in two tubes containing sodium hydroxide pellets and calcium chloride, respectively. The detection limits of this method were 1.8 ng dm−3 for arsenic and 9.4 ng dm−3 for antimony in the case of 100-cm3 sample volumes. Therefore, it is suitable for determination of trace arsenic and antimony in natural waters.

Catalytic solid substrate-room temperature phosphorimetry for the determination of trace As(V) based on oxidising reaction between hydrogen peroxide and fullerenol using tween-80 as sensitizer

A new catalytic solid substrate-room temperature phosphorimetry (SS-RTP) for the determination of trace arsenic(V) has been established. It is based on the fact that fullerenol (F-ol) emitted strong and stable room temperature phosphorescence (RTP) on nitric acid cellulose membrane (NCM) substrate. H2O2 could oxidise F-ol to cause the quenching of RTP. As(V) could catalyse H2O2 to oxidise F-ol and decrease the RTP signal of F-ol sharply. After adding tween-80 in the system, its ΔI p enhanced 7.7 times compared with the without-tween-80 levels. Under the optimum conditions, the linear dynamic range of this method was 0.016−11.2 ag spot−1 with a detection limit (LD) of 9.3 zg spot−1 (corresponding concentration: 2.3 × 10−17 g mL−1). This sensitive, simple and selective method has been successfully applied to the determination of trace As(V) in human hair and tea samples. The reaction mechanism for SS-RTP is also discussed.

Determination of trace arsenic(III) by differential-pulse anodic stripping voltammetry with in-situ plated bismuth-film electrode

A sensitive and precise method is presented for the determination of As(III) by differential-pulse anodic stripping voltammery (DPASV). This method is based on the co-deposition of As(III) with Bi(III) onto a basal-plane type of pyrolytic graphite substrate at an accumulation step. DPASV studies indicate that the As was oxidized with anodic scans to give an enhanced anodic peak at about 500 mV vs. Ag/AgCl. Addition of L-cysteine to test solutions was found to be highly effective to obtain reproducible oxidation responses due to As(0) → As(III). A linear relationship between the anodic stripping peak-current ratio (I As/I Bi) and As(III) concentration was observed over the concentration range from 0.0200 µg L−1 to 18.0 µg L−1. The detection limit of As(III) was 0.012 µg L−1 at a deposition time of 180 s. The relative standard deviation was 2.85% (n = 8) at a concentration of 10.0 µg L−1 As(III). Analytical results demonstrate that the determination of As(III) in real water samples is possible by the proposed method.

Determination of trace arsenic(V) by catalytic solid substrate-room temperature phosphorescence quenching method

In the H 2SO 4 medium and in the presence of dodecylbenzene sulfonic acid sodiumsalt (DBS), dimethyl yellow (R) could emit strong and stable solid substrate room temperature phosphorescence (RTP) on filter paper. And NaIO 4 could oxidize R to cause the RTP quenching. Arsenic(V) could catalyze the reaction of NaIO 4 oxidizing R, which caused the RTP sharply quenching. The reducing value of phosphorescence intensity (Δ I p) for the system with DBS is 3.3 times higher than that without DBS. Moreover, the Δ I p is proportional to the concentration of As(V). Based on the facts above, a new RTP quenching method for the determination of trace As(V) has been established.

Determination of trace arsenic on hanging copper amalgam drop electrode

Hanging copper amalgam drop electrode has been applied for trace determination of arsenic by cathodic stripping analysis. Detection limit for As(III) as low as 0.33 nM (0.02 μg/L) at deposition time (240 s) could be obtained. For seven successive determinations of As(III) at concentration of 5 nM relative standard deviation was 2.5% ( n = 7). Interferences from selected metals and surfactant substances were examined. Absence of copper ions in sample solution causes easier optimization and makes method less vulnerable on contamination. The developed method was validated by analysis of certified reference materials (CRMs) and applied to arsenic determinations in natural water samples.

Determination of trace arsenic with DDTC-Na by cathodic stripping voltammetry in presence of copper ions

The cathodic stripping voltammetry is used to determine arsenic in presence of copper and sodium diethyldithiocarbamate (DDTC-Na). The method showed several advantages in comparison to analogous one without DDTC-Na: higher sensitivity, substantially lower detection limit already at short deposition time, better repeatability and reproducibility. Detection limit of As(III) as low as 0.06 nM (0.004 ppb) possible to obtain with deposition time as short as 50 s. The lower detection limit is achievable at longer deposition time. The repeatability measured as relative standard deviation is 2%. Interferences from selected inorganic ions and surfactants were examined. Unique application of DDTC-Na was found as useful modification of the CSV method. The proposed method is successfully applied to arsenic determinations and speciation in drinking water samples.

Determination of Arsenic and Mercury in Chinese Medicinal Herbs by Atomic Fluorescence Spectrometry with Closed‐Vessel Microwave Digestion

A simple method was developed for the determination of trace arsenic and mercury in Chinese medicinal herbs. The samples were digested in closed‐Teflon vessels in a microwave oven, and followed with hydride generation atomic fluorescence spectrometric measurements. The experimental conditions for the digestion were carefully optimized using an orthogonal design. The accuracy of the method was validated by recovery experiments, and the analytical results for arsenic in seven medicinal herbs (Codonopsis pilosula, Radix angelicae sinensis, Aconitum carmichaeli debx, crude aconite root, giant typhonium rhizome, Rhizoma typhonii, and Radix aconiti lateralis preparata) were found to agree well with those by inductively coupled plasma atomic emission spectrometry (ICP‐AES). The linear dynamic range of the calibration curve was in the range of 0.1–400 ng/mL for arsenic, and the correlation coefficient was better than 0.999. The limit of detection was 0.1 ng/mL for arsenic. For mercury, the determination was accomplished through mercury cold vapor generation in the same instrumental system. The linear dynamic range was 0.03–250 ng/mL, with a limit of detection of 0.03 ng/mL for mercury. This was a rapid, convenient, precise, and cost‐effective method.

In situ preconcentration and determination of trace arsenic in botanical samples by hydride generation-graphite furnace atomic absorption spectrometry with Pd–Zr as chemical modifier

A method has been described for the determination of arsenic by graphite furnace atomic absorption spectrometry (GFAAS) with hydride generation (HG) and in situ preconcentration techniques using Pd–Zr chemical modifier. The experimental conditions studied include acidity, concentration of NaBH 4, adsorption temperature, amounts of modifier, which affect the generation of hydride, adsorption efficiency and the pyrolysis and atomization temperatures. The highest pyrolysis temperature and adsorption efficiency of arsine were obtained when Pd–Zr mixture was used as the adsorption agent and chemical modifier. The characteristic mass of the method (gives an integrated absorbance of 0.0044 s) was found to be 18 pg and the absolute detection limit (3 σ) of 15 pg was obtained. The proposed method was applied to the determination of arsenic in botanical samples with a recovery range of 96–105%.

Determination of Arsenic with Michler's Thioketone

Michler's thioketone is proposed as the reagent for the spectrophotometric determination of trace arsenic(V). The molar absorptivity of the colored product of interaction between Michler's thioketone and molybdoarsenic acid is (1.02 ± 0.04) × 105at 640 nm. A procedure is developed for the extraction–photometric determination of arsenic in tap and mineral waters. The added–found method is used. The determination limit of arsenic is 0.003 mg/L; in the concentration range 0.008–0.12 mg/L, the relative standard deviation varies from 20 to 8 %.

Study of the Simultaneous Determination of Trace Arsenic and Mercury by Flow Injection/Hydride Generation/ICP-AES

ABSTRACT A combined system of flow injection/hydride generation coupled with multichannel plasma spectrometer was put forward and applied to the simultaneous determination of trace arsenic and mercury. The interface between flow injection hydride generation (FI-HG) and ICP-AES, gas/liquid separator and main experimental parameters were described. The detection limits of the proposed method could be achieved to 0.x μg/L level; The RSD 1.4% and 1.3% at 10 ng/mL levels of As and Hg respectively. The frequency of sampling was 150/h with 80μL sampling volume. The proposed method has been applied to the simultaneous determination of As and Hg in some real samples.

Determination of trace arsenic in hydrofluoric acid by hydride generation and atomic absorption spectrometry

Practical procedures are given for determination of arsenic(III) and (V) in hydrofluoric acid by means of hydride generation and atomic absorption spectrometry. Arsenic(III) can be determined by direct generation of arsine with sodium borohydride in hydrochloric/hydrofluoric acid medium, arsenic(V) being only slightly reduced under the conditions used. For its determination, arsenic(V) has to be prereduced with potassium iodide, and even then its reduction to arsenic(III) and then arsine is far from complete. It is possible to determine it in presence of arsenic(III) by a difference method, but this is recommended only if the As(V)/As(III) ratio is greater than 1. Total arsenic can be determined after oxidation of As(III) and evaporation of most of the hydrofluoric acid. The limit of determination is 5 μg/l for arsenic(III) and 0.25 μg/l for total arsenic; the relative standard deviation is about 10%.

Determination of trace arsenic, antimony, selenium and tellurium in various oxidation states in water by hydride generation and atomic-absorption spectrophotometry after enrichment and separation with thiol cotton

A novel procedure for determination of trace As(III) and As(V), Sb(III) and Sb(V), Se(IV) and Se(VI), Te(IV) and Te(VI) in water by atomic-absorption spectrophotometry after separation and enrichment with “thiol cotton” and hydride generation has been established. The sorption behaviour of various oxidation states of arsenic, antimony, selenium and tellurium, and the conditions of quantitative sorption and desorption of these species were studied. The procedures for reducing species from higher oxidation states were optimized. Interferences from other species and their elimination were investigated. The selectivity of the procedure for the determination of species in higher and lower oxidation states was examined. The procedure has been successfully used to determine arsenic, antimony, selenium and tellurium in water, in the range from pg ml to ng ml . The recoveries for added spikes were in the range 90–110%, with coefficients of variation in the range 3–8%