Analytica Chimica Acta 554 (2005) 25–30 A sensitive procedure for the rapid determination of arsenic(III) by flow injection analysis and chemiluminescence detection Sakchai Satienperakul a , Terence J. Cardwell a,∗ , Spas D. Kolev b , Claire E. Lenehan c,1 , Neil W. Barnett c a Analytical Chemistry Laboratories, Department of Chemistry, La Trobe University, Bundoora, Vic. 3086, Australia b School of Chemistry, The University of Melbourne, Melbourne, Vic. 3010, Australia c School of Biological and Chemical Sciences, Deakin University, Geelong, Vic. 3217, Australia Received 14 June 2005; received in revised form 11 August 2005; accepted 12 August 2005 Available online 5 October 2005 Abstract A novel chemiluminescence flow injection procedure for the determination of As(III) in aqueous samples is described. The method involves injection of As(III) samples into a 1% (m/v) sodium hexametaphosphate in 0.02 M H 2 SO 4 carrier stream, which then merges at a Y-piece with a reagent stream consisting of potassium permanganate (5.0 × 10 -5 M) made up in the acidic sodium hexametaphosphate carrier solution. The chemiluminescence intensity of the resulting reaction mixture was measured at a photomultiplier tube operated at a voltage of 0.93kV. Under optimized conditions, the method is characterised by a linear range from 0.5 to 5.0 gl -1 , a detection limit of 0.3 gl -1 and a sampling frequency of 150 h -1 . The effects of common anionic and cationic interferences were investigated, and it was found that the only ions to cause serious interference were those which react with potassium permanganate, namely sulphide, iodide and ferrous. © 2005 Elsevier B.V. All rights reserved. Keywords: Flow injection; Chemiluminescence; Arsenic; Acidic potassium permanganate 1. Introduction Arsenic occurs in the environment in many and varied organic and inorganic forms. In ground and surface waters, arsenic is generally found in the inorganic forms of arsenite (As(III)) and arsenate (As(V)), both of which are acutely toxic if swallowed. Ingestion of large doses leads to gastrointestinal, cardiovascular and nervous system disfunction and eventually death. Long-term exposure to low concentrations of arsenic has been linked to increased risks of cancer. With the exception of occupational exposure by inhalation, arsenic is generally introduced to the body through the ingestion of food and water [1]. Concentrations of arsenic in surface and ground waters generally range from 1 to 10 gl -1 , but elevated levels (100–5000 gl -1 ) have been reported in groundwaters in China [2], and India and Bangladesh [3]. Consequently the World Health Organisation has identified ∗ Corresponding author. Tel.: +61 3 9479 2536; fax: +61 3 9479 1399. E-mail address: t.cardwell@latrobe.edu.au (T.J. Cardwell). 1 Present address: School of Chemistry, Physics and Earth Sciences, Flinders University, Adelaide, SA 5001, Australia. an urgent requirement for the development of simple, low-cost equipment for field measurement of arsenic [4]. The maximum contaminant level (MCL) of arsenic in drinking water recom- mended for implementation in 2006 in the USA is 10 gl -1 [5] and the MCL for Australia is 7 gl -1 [6]. There are several accepted analytical methods currently avail- able for the measurement of arsenic in environmental samples. These include atomic fluorescence spectrometry (AFS) [7], graphite furnace atomic absorption spectrometry (GFAAS) [8], hydride generation atomic absorption spectrometry (HGAAS) [9], inductively coupled plasma atomic emission spectrometry (ICP-AES) [10] and inductively coupled plasma mass spectrom- etry (ICP-MS) [11]. However, these methods require compara- tively expensive equipment and they are not readily amenable to portable instrumentation. Flow injection (FI) analysis has proved to be suitable for on-line analysis because of its low reagent and sample consump- tion, high sampling frequency and ease of automation [12,13]. Spectrophotometric determination based on the formation of molybdenum blue has been used by several workers for the detection of arsenate in FI [14–16]. Linares et al. described 0003-2670/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.aca.2005.08.025