Current Analytical Chemistry, 2009, 5, 29-34 29 1573-4110/09 $55.00+.00 © 2009 Bentham Science Publishers Ltd. Direct Quantitative Determination of Total Arsenic in Natural Hotwaters by Anodic Stripping Voltammetry at the Rotating Lateral Gold Electrode Selehattin Yilmaz a,* , Baris Baba a , Alper Baba b , Sultan Yagmur a and Meryem Citak a a Canakkale Onsekiz Mart University, Faculty of Arts and Sciences, Department of Analytical Chemistry, 17020 Canak- kale, Turkey; b Canakkale Onsekiz Mart University, Faculty of Engineering and Architecture, Department of Geological Engineering, 17020 Canakkale, Turkey Abstract: A simple, rapid, selective and sensitive differential pulse anodic stripping voltammetric (DPASV) technique for the direct quantitative determination of inorganic total arsenic in natural hotwater was developed. The electrochemical de- termination of total arsenic has been carried out at the novel rotating lateral gold electrode in hydrochloric acid solution (37 % w/w). The analysis was performed with a special gold electrode whose active surface was located on the side. Re- productivity of measurement was achieved by the conditioning of the gold electrode. This was done every day before the measurements as well as when the background current varied strongly from measurement to measurement. The determina- tion limit of 0.5 g L -1 was achieved with 10 mL sample solution. The total arsenic concentration was made by appropri- ate selection of the deposition potential. During the deposition step, the total arsenic content was reduced at -1200 mV by nascent hydogen to As o . During the subsequent voltammetric determination, the preconcentration As o was again oxidized to determine the level. The method was applied successfully to the direct quantitative determination of total inorganic ar- senic in hotwater. In order to show the accuracy of the results developed from voltammetric technique, the values obtained were compared with those obtained from inductively coupled plasma mass spectrometry (ICP-MS). Keywords: Total arsenic, Determination, Natural hotwater, Anodic stripping voltammetry, Rotating lateral gold electrode. 1. INTRODUCTION Arsenic (As) is a common contaminant of natural waters. The toxicological, physiological and geochemical behaviour depends on its oxidation state, toxicity being especially due to inorganic arsenite. Living organisms are exposed to the toxic As primarily from food and water. Exposure to As can cause a variety of adverse health effects, including dermal changes, respiratory, cardiovascular, gastrointestinal, geno- toxic, mutagenic and carcinogenic effects [1]. As occurs in the natural environment in four oxidation states: As (V), As (III), As (0) and As (-III). The mobility and toxicity of arse- nic are determined by its oxidation state [2], thus the behav- iour of arsenic species will change depending on the biotic and abiotic conditions in water. The contamination of groundwater with arsenic has al- ready been reported in 20 countries, out of which four major instances are from Asia [3-11]. These include Bangladesh, India, Inner Mongolia and Taiwan. Fifty districts of Bangla- desh and nine in West Bengal (India) have arsenic levels in drinking water above the World Health Organization's (WHO) arsenic guideline value of 10 g L -1 [12]. The area and population of these districts with contaminated drinking water are 118 848 km 2 and 104.9 million in Bangladesh and 38 865 km 2 and 42.7 million in West Bengal [11]. Several contamination has also been reported in Vietnam, where *Adress correspondence to this author at the Canakkale Onsekiz Mart Uni- versity, Faculty of Arts and Sciences, Department of Analytical Chemistry, 17020 Canakkale, Turkey; Tel: +90 286 2180018/1857; Fax: +90 286 2180533; E-mail: seletyilmaz@hotmail.com several million habitants are at considerable risk of chronic arsenic poisoning, with contamination levels reach up to 3050 g L -1 in rural groundwater samples [13]. In groundwater, arsenic is predominantly present as As (III) and As (V), with a minor amount of methyl and di- methyl arsenic compounds being detected (Scheme 1) [14]. HO As OH O III O As OH OH O V O As OH CH 3 O V O As CH 3 CH 3 O V HO As CH 3 O III Arsenite Arsenate Methylarsenite Dimethylarsenite Dimethylarsenate Methylarsenate H 3 C As CH 3 O III Scheme 1. Arsenic species found in water. Genereally, atomic absorption spectrometry (AAS), atomic fluorescence spectrometry (AFS), atomic emission spectrometry (AES), differential pulse polarography (DPP), electrothermal atomic absorption spectrometry ( ETAAS) electrothermal vaporization (ETV), flow injection (FI), graphite furnace atomic absorption spectrometry (GFAAS), hydride generation (HG), hanging mercury drop electrode (HMDE), high pressure liquid chromatography (HPLC),