ISOTOPE-DILUTION ANALYSIS OF SE IN HUMAN BLOOD-SERUM BY USING HIGH-POWER NITROGEN MICROWAVE-INDUCED PLASMA-MASS SPECTROMETRY COUPLED WITH AHYDRIDE GENERATION TECHNIQUE

To establish a method for sensitive, accurate, and precise determinati on of Se in real samples, isotope dilution analysis using high-power n itrogen microwave-induced plasma mass spectrometry (N-2 MIP-IDMS) was conducted. In this study, freeze-dried human blood serum (Standard Ref erence Material, NIES No. 4) provided by NIES (National Institute for Environmental Studies) was used as a real sample. The measured isotope s of Se were Se-78 and Se-80 which are the major isotopes of Se. The a ppropriate amount of a Se spike solution was theoretically calculated by using an error multiplication factor (F) and was confirmed experime ntally for the isotope dilution analysis. The mass discrimination effe ct was corrected for by using a standard Se solution for the measureme nt of Se isotope ratios in the spiked sample. However, the sensitivity for the detection of Se was not so good and the precision of the dete rmination was not improved (2-3%) by N-2 MIP-IDMS with use of the conv entional nebulizer. Therefore, a hydride generation system was connect ed to N2MIP-IDMS as a sample introduction system (HG-N-2 MIP-IDMS) in order to establish a more sensitive detection and a more precise deter mination of Se. A detection limit (3rho) of 10pg mL(-1) could be achie ved, and the RSD was less than 1% at the concentration level of 5.0-10 .0 ng mL(-1) by HG-N-2 MIP-IDMS. The analytical results were found to be in a good agreement with those obtained by the standard addition me thod using conventional Ar ICPMS.