Determination of Trace Amounts of Arsenic(III) and Arsenic(V) in Drinking Water and Arsenic(III) Vapor in Air by Graphite-Furnace Atomic Absorption Spectrophotometry Using 2,3-Dimercaptopropane-1-sulfonate as a Complexing Agent

Abstract

Cumulative excess amounts of arsenic in our body may cause liver, lung, kidney, bladder or skin cancers, and chronic poisoning. [1][2][3] In the southwest coastal region of Taiwan (Tainan and Chia-I county) 1 , a few residents had for more than 30 years been drinking deep groundwater containing high levels (600 -700 µg/l) of arsenic compounds 4,5 , which caused Blackfoot Disease. Based on this phenomenon, the USEPA and Taiwan government have considered decreasing the allowable contamination levels of total arsenic in drinking water to be 2 -20 µg/l 6 and 10 µg/l, respectively.As(III) is considered to be more toxic than As(V), which is in turn more toxic than organic arsenics. The 8-h average permissible exposure limit for As 2 O 3 in air was recommended not to exceed 0.01 mg/m 3 of As by OSHA.7 Several methods commonly used for the determination of the amounts of arsenic species in water are flow-injection with graphite-furnace atomic absorption spectrometry (FI-GFAAS) 8 , or with hydride generation atomic absorption spectrometry (FI-HGAAS); 9,10 chelating extraction and then HGAAS 11 , or neutron activation analysis; 12 HPLC and then HGAAS 4 , or HG-ICPMS; 13 and ion chromatography-HG-ICPMS.14 The As 2 O 3 vapor in air determined by NIOSH 7 was collected on a Na 2 CO 3 -impregnated cellulose ester membrane. After digestion and the addition of Ni 2+ , an aliquot (25 µl) was analyzed by GFAAS. The detection limit was 0.06 µg per sample and the linear range was 0.67 -32 µg/m 3 as As for a 400-l sample.2,3-Dimercaptopropane-1-sulfonate (DMPS) has been used as an antidote for mice 15 and human 16 poisoning with sodium arsenite, and Ni 2+ has been commonly used as a chemical modifier in GFAAS 5,17,18 to form a stable compound of NiAs. 19 In this paper, we used DMPS as a complexing agent for As(III) in ammonium acetate buffer of pH 5.5. The complex of As(III)-DMPS was selectively retained on Sep-Pak C 18 cartridges and then concentrated in methanol; while As(V) could not be retained in this way. The As(V) was pre-reduced to As(III) with L-cysteine 9,13,20,21 and the total amount of As(III)+As(V) was determined. The amount of As(V) was obtained by subtracting As(III) from [As(III)+As(V)]. Hence, trace amounts of As(III) (up to 200 ng) and As(V) (up to 100 ng) in drinking water (25 ml) could be accurately determined by GFAAS. The applicability for the determination of As(III) vapor in air was also attempted. Experimental ApparatusA Hitachi Z-8000 graphite-furnace atomic absorption spectrophotometer, equipped with a Zeeman back- Department of Environmental Science, Tunghai University, Taichung 407, Taiwan, Republic of ChinaAs(III) (12.5 -200 ng) in drinking water (25 ml) reacted with 2,3-dimercaptopropane-1-sulfonate (DMPS, 0.60 mg) in ammonium acetate buffer (2.0 mmol, pH 5.5) and formed a complex of As(III)-DMPS. The complex was selectively retained on two Sep-Pak C18 cartridges in series, while As(V) could not be retained. Each cartridge was eluted with methanol (2.00 ml). After addition of Ni 2+ (2.0 mg), a portion ...

Fluorometric sensing of ultralow As(iii) concentrations using Ag doped hollow CdS/ZnS bi-layer nanoparticles

“…44,45 Due to these reasons, the easy and low level detection of arsenic in water has become a challenge in recent years. Different analytical methods have been used for the detection of arsenic such as atomic absorption spectroscopy (AAS), 46 hydride generation atomic absorption spectrometry (HG-AAS), 47 polarographic techniques, 48 inductively coupled plasma (ICP), 49 ICP atomic emission spectrometry (ICP-AES), ICP mass spectrometry (ICP-MS), 50 high performance liquid chromatography (HPLC) with optical spectrometric detection, 51 and voltammetry studies. 52,53 While considering its low detection limit, the ICP-MS method can detect up to a very low concentration of arsenic (∼0.01 µg L −1 ), but the analysis cost is very high, because the instrument used is very costly and, to date, the sample preparation for this method is tedious and time consuming.…”

Non-chromatographic hydride generation atomic spectrometric techniques for the speciation analysis of arsenic, antimony, selenium, and tellurium in water samples—a review

“…Selective HG from As(III) species and total As after reduction was reported by several authors [120-122, 124, 172]. SPE using APDC [173] and 2,3-dimercaptopropane-1-sulfonate on C 18 cartridge was reported [174]. Co-precipitation of As(III) with Cu-PDC and total arsenic after L-cysteine reduction was reported with a ng L À1 LOD [175].…”

Design of Fluorescence-Enhanced Silver Nanoisland Chips for High-Throughput and Rapid Arsenite Assay

“… 5 − 7 Various approaches including atomic absorption spectroscopy, inductively coupled plasma mass spectrometry, atomic fluorescence spectroscopy, and high-performance liquid chromatography have been utilized for the detection of As(III) with stable analysis, good reproducibility, and excellent sensitivity. 8 − 11 However, these complicated and costly high-end instruments require well-trained technicians for their maintenance and operation. Moreover, the detection of As(III) with these instruments usually involves complex, tedious, and time-consuming sample preparation in a central laboratory.…”