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 separator which was closed with an electromagnetic pinch valve and then swept continuously into the torch of a high-resolution inductively coupled plasma-mass spectrometer. The system was operated with variable speed-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 eliminated by using Chelex 100 resin. The detection limits (3 times the signal-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 biological standard reference materials obtained from the National Institute of Science and Technology (NIST), USA, and the National Research Council(NRC), Canada, were within the certified values. The arsenic and selenium contents in river water were determined by the present method.