Determination of selenium in blood serum by hydride generation inductively coupled plasma mass spectrometry

Continuous flow hydride generation inductively coupled plasma mass spectrometry (ICP-MS) was used for the determination of selenium:in blood-serum, The connector between the- spray chamber and the ICP torch was replaced by a Y-piece, which allowed the hydride gases to be mixed with argon (fed through the nebulizer and spray chamber) before arriving at the plasma. The performance of the system was optimized with and without introduction of water to the nebulizer (wet and dry plasma), The dry plasma offered high short-term signal stability with the relative standard deviation approaching statistical limits. This was not the case for the wet plasma, but the latter demonstrated higher sensitivity, and when combined with internal standard correction, good long and short-term stability, The influence of iron and copper on the selenium signal as evaluated and showed no significant effect at the levels expected in serum, In order to achieve acceptable accuracy, special attention was paid to the choice of digestion procedure. Good precision (2.27% relative standard deviation) was obtained on nine separate analyses of a quality control blood serum, Analysis of second- generation human blood: serum reference material and of three different quality control blood serum samples gave results within two standard deviations of the means, a negative bias being observed in all cases. Possible explanations of this bias are discussed.