The Method of Arsenic Speciation

The speciation for arsenious acid (As(Ⅲ)), arsenic acid (As(Ⅴ)), mono-methyl arsenate (MMA) and di-methyl arsenate (DMA) was developed for environmental water samples. The separation of the four arsenic species was achieved by means of a IC-Anion-PW ion-exchange chromatographic system at pH 6.0, and a gradient programe by using phosphate as mobile phase. DMA was converted to As(V) by using 20g/L K2S2O8 solution and UV-irradiation. AFS measurement was accomplished by using 10% hydrochloric acid as carrier solution, 20g/L KBH4+ 5g/L KOH solution as reducing agent. It is found that it is good on linearity for the four arsenic species in the range of 0-20 mg/L, and has low detection limit around 0.1 μg/L, high recovery between 95%-110%, and lower relative standard deviation than 3%.