DETERMINATION OF ARSENIC AND SELENIUM IN RIVER WATER BY HYDRIDE GENERATION INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY WITH HIGH-RESOLUTION

Hydride generated in a mixing coil was separated in a gas-liquid separ ator which was closed with an electromagnetic pinch valve and then swe pt continuously into the torch of a high-resolution inductively couple d plasma-mass spectrometer. The system was operated with variable spee d-peristaltic pumps by manipulating electromagnetic relays and a timer . Water vapor in the hydride gas was removed by inserting a glass trap immersed in an ice bath. Interference with transition matals was elim inated by using Chelex 100 resin. The detection limits (3 times the si gnal-to-noise ratio) of arsenic and selenium are 0.03 and 0.06 ng/ml, respectively, at a resolution of 10000. The accuracies checked with bi ological standard reference materials obtained from the National Insti tute of Science and Technology (NIST), USA, and the National Research Council(NRC), Canada, were within the certified values. The arsenic an d selenium contents in river water were determined by the present meth od.