Determination of organic forms of mercury and arsenic in water and atmospheric samples by gas chromatography-atomic absorption

Abstract

A study of the determination of dimethylmercury, methylmercury, ethylmercury, dimethylarsine and methylarsine in water and in atmospheric samples was carried out. The studied compounds were extracted from water by a benzene-toluene mixture, evaporated if necessary and analyzed by gas chromatography with atomic absorption spectrometry as a detector. A 45 cm column packed with Tenax was used. The detection limits of the procedure were: 4 ng Hg in dimethylmercury and methylmercury, 5 ng Hg in ethylmercury and 25 ng As in dimethyl and methylarsine in 1 l water. Methylmercury and ethylmercury were detected in Ontario natural waters and snow at 12–45 and 7–15 ng Hg l−1 respectively. The level of methylarsine varied from 40 to 90 ng l−1. Dimethylmercury and dimethylarsine were detected only in the Humber River.