Atomic fluorescence spectrometric determination of trace amounts of arsenic and antimony in drinking water by continuous hydride generation

A highly sensitive and simple method has been developed for the determination of As(III), total As, Sb(III) and total Sb in drinking water samples by continuous hydride generation and atomic fluorescence spectrometry (HGAFS). For As determination, water samples aspirated in a carrier of 2 mol l−1 HCl were merged with a reducing NaBH4 3%(m/v) solution, with sample and NaBH4 flow rates of 12.5 and 1.5 ml min−1 respectively. The hydride generated in a 170 cm reaction coil was transported to the detector with an Ar flow of 400 ml min−1, and a limit of detection between 5 and 20 ng l−1 was obtained. For Sb determination, 2.5 mol l−1 HCl and 2%(m/v) NaBH4 were employed, with respective flow rates of 9.7 and 2 ml min−1. The hydride generated in a 50 cm reaction coil was transported to the detector with an Ar flow rate of 300 ml min−1, and a limit of detection between 6 and 14 ng l−1 was obtained. Determination of the total concentration of these elements was obtained after a previous reduction with KI. Recovery studies of different added concentrations of these species in natural water samples were between 93 and 104% for As(III), 96–103% for As(V), 93–101% for Sb(III) and 90–119% for Sb(V).