DETERMINATION OF MULTIPLE SELENIUM STABLE ISOTOPE TRACERS BY INDUCTIVELY COUPLED PLASMA MASS-SPECTROMETRY

Inductively coupled plasma mass spectrometry with hydride generation was used for the determination of Se stable isotope tracer enrichment in standard solutions and biological materials. Up to three enriched isotopes, Se-76, Se-77 and Se-82, were determined, while Se-78 served as the reference isotope. Tracer enrichment was linearly determined with or without simultaneous additions of two other Se stable isotope tracers. Multiple additions of enriched Se-77 and enriched Se-82 at the low levels required for in vivo tracers were accurately determined in the presence of a much greater addition of enriched Se-76 (for isotope dilution analysis) in spite of the significant Se-77 and Se-82 impurities introduced with the enriched Se-76. Detection limits for Se stable isotope tracers were sufficient to determine up to a 200-fold dilution of tracer following an initial tracer enrichment equivalent to 10% of the mass of the natural Se pool.