Analytical Sciences

Optimization of a Flow Injection System with Amperometric Detection for Arsenic Determination

Aleksandar LOLIC, Snezana NIKOLIC, and Jelena MUTIC

Faculty of Chemistry, University of Belgrade, Studentski trg 16, P. O. Box 158, 11000 Belgrade, Serbia

A selective and sensitive analytical procedure for rapid arsenic determination by gas-diffusion flow injection analysis with amperometric detection was developed. The method is based on the arsenite reduction by NaBH₄. Derived arsine diffuses through a PTF membrane into the acceptor flow stream and is amperometrically determined on a platinum working electrode. The limit of detection (3σ) at room temperature was 5 µg/dm³ of As(III). The relative standard deviation for a 1 mg/dm³ As(III) standard was 1.96% for six repetitive injections. Arsenic(V) was determined after its prereduction with potassium iodide. Arsenic determination was not interferred with by 1 mg/dm³ Sb(III), 5 mg/dm³ Sn(II), 10 mg/dm³ Se(IV), 1 mg/dm³ As(V), 1 mg/dm³ hydrasine, 1 mg/dm³ Fe(II) or 0.5 mg/dm³ Fe(III) solution. The throughput of this method was 60 analyses per hour. This method was successfully applied to arsenic determination in some power plant waste water samples.

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