Optimization of CE Separation of Roxarsone and Several Arsenic Compounds

Abstract. Capillary electrophoresis with direct UV detection was used for the separation of arsenite As(III), arsenate As(V), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), phenylarsonic acid (PAA), p-arsanilic acid (p-ASA) and roxarsone (3-NHPAA). The separation was achieved in a fused silica capillary using a high sensitivity detection cell with diode array detector. A 15 mM phosphate buffer was used as the background electrolyte. The influence of electrolyte pH, applied voltage and wavelength were investigated in this research where the optimum conditions obtained were at pH 6.0,25 kV voltage and 191 nm detection wavelength. The optimized method provided a limit of detection of 0.193 mg/L for As(III). Reproducibility of the analytes was in the range of 4.6%-10.5% RSD.