A simple manifold flow injection analysis for determining phosphorus in the presence of arsenate

A simple manifold flow injection analysis (FIA) for determining phosphorus in the presence of arsenate in water, by the on-line reduction of As(V) to As(III) using sodium sulfite. The FIA method is applicable for the determination of phosphorus in water samples containing less than 0.37 mu g center dot mL(-1) of AsO4 (3-). A solution obtained by mixing 6.30 g of Na-2 SO3 (1 M), 5.0 ml H2SO4 18 M completed up to 50 ml with deionized distilled water was used to reduce on line As(V) to As(III), using a reactor of 0.30 m. The limit of detection is 0.05584 +/- 0.00167 mu g center dot mL(-1) P-PO4 (3-) and sampling frequency is 45 samples per hour. It is a simple and low cost methodology, easily applicable in the determination of phosphorus in samples of water contaminated with arsenate.