DETERMINATION OF ARSENIC, ANTIMONY, BISMUTH, SELENIUM AND TIN IN BIOLOGICAL AND ENVIRONMENTAL-SAMPLES BY CONTINUOUS-FLOW HYDRIDE GENERATION ICP-AES WITHOUT GAS-LIQUID SEPARATOR

A simple continuous flow hydride generation system without conventional gas-liquid phase separator was developed for the determination of As, Se, Sb, Bi and Sn in biological and environmental samples by sequential ICP-AES with 1.5 kW power. The interchange of operating mode from normal solution nebulization to hydride generation or vice versa can easily be done without interrupting the plasma in this system. Two digestion methods were compared, i.e. the pressurized digestion with HNO3 in a closed vessel and HNO3/HClO4/H2SO4 acid digestion in an open system. It was found that further treatment is necessary after normal pressurized digestion for As determination in marine samples, e.g. mussel. Interferences, especially by copper and nickel were examined and completely eliminated up to 10-mu-g/ml by using a mixed reductant (3% NaBH4 and 2% KI) with lower flow rate as well as the sample solution media of 30% HCl (v/v) and 20% HNO3 (v/v). The effect of KI on the elemental oxidation states of As, Se and Sb is discussed. The accuracy of the method was validated by the analysis of a number of biological and environmental SRM's of NIST, BCR and NIES. Most results were in agreement with the certified values or reference values. The detection limits for these elements were in the range of 0.x ng/ml.