Electrochemical Hydride Generation-Atomic Absorption Spectrometric Determination of Inorganic Arsenic of Different Valency State

High rates of electrochemical hydride generation (EC-HG) of inorganic arsenic in tri-and penta-valent state were obtained at the glassy carbon cathode in the electrolytic cell.Differences in sensitivity and in slopes of calibration curves for As(Ⅲ) and As(Ⅴ) were also observed.Based on these facts and by selecting different conditions of electrolytic currents at 0.6 A and 1.2 A,EC-HG was hyphenated with AAS for the speciation analysis of inorganic arsenic.Various analytical factors,including the choice of supporting electrolyte,electrolytic current,interfering substances and etc.,were studied in detail.Under the optimized conditions,detection limits of the method for As(Ⅲ) and As(Ⅴ) were found to be 0.2 μg·L-1 and 0.4 μg·L-1 respectively.Precision of the method was tested at the concentration level of 20 μg·L-1,and values of RSD′s (n=6) obtained were 1.9% for As(Ⅲ) and 3.1% for As(Ⅴ).The present method was used in the analysis of a CRM sample of human hair (GBW 09101),the results of total arsenic determined were in consistency with the certified value.