Highly Sensitive Voltammetric Speciation and Determination of Inorganic Arsenic in Water and Alloy Samples Using Ammonium 2-Amino-1-Cyclopentene-1-Dithiocarboxylate

A simple, fast, reproducible (2.5% RSD at 3.0 mu g/L), and sensitive method is described for quantifying As(III) (0.3 mu g/L detection limit, 0.5-440 mu g/L dynamic range). Anodic stripping voltammetry (ASV) is performed after accumulating arsenic at a mercury film electrode at -0.350 V vs. Ag/AgCl (saturated KCl) for 20 s in 0.2 M HCl containing 8 mu M ammonium 2-amino-1-cyclopentene-1-dithiocarboxylate (AACD), without oxygen removal. This is the first report of using AACD in ASV and in electrochemical quantification of As(III). Total arsenic is determined after sodium-sulfite-reduction of As(V) to As(III). Interferences are minimal. Method validation involved water and metal alloy samples.