SIMULTANEOUS DETERMINATION OF ARSENIC(V) AND ARSENIC(III) IN WATER BY INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRY USING REDUCTION OF ARSENIC(V) BY L-CYSTEINE AND A SMALL CO-CENTRIC HYDRIDE GENERATOR WITHOUT A GAS-LIQUID SEPARATOR

A small co-centric hydride generator can be used to determine arsenic by inductively coupled plasma atomic emission spectrometry with a minitorch of 0.65 kW power. Because the reaction of arsenic(V) with L-cysteine is linearly dependent on time up to 9 min, the determination of arsenic(V) based on reduction kinetics is possible. Interferences from transition elements are low. The detection limit for arsenic(V) is 3.4 ng ml(-1) and for arsenic(III) 0.7 ng ml(-1). The relative standard deviation for ten determinations of solutions containing 100 ng ml(-1) As(V) was 1.45% and for a solution containing 100 ng ml(-1) As(III) it is 1.21%. A major advantage of this system is the simultaneous determination of arsenic(V) and arsenic(III) under conditions of low acid and low power using a normal spray chamber.