PALLADIUM(II), MAGNESIUM(II), AND BARIUM(II) NITRATE COMBINATIONS FOR MATRIX MODIFICATION IN ELECTROTHERMAL ATOMIC-ABSORPTION MEASUREMENT OF TOTAL SELENIUM IN HUMAN URINE

Electrothermal atomic absorption spectrometry with a temperature-stabilizing platform and palladium(II) nitrate-magnesium nitrate-barium nitrate matrix modifier combination was used to measure total selenium concentrations in 0.5-ml samples of human urine. The method was validated by analysis of desiccated, standard urine samples (SRM 2670) from NIST. The peak height response was linear from 0 to 150 mu g Se/ liter urine with a sensitivity of 0.001 absorbance unit/ mu g Se/liter and a detection limit of 6 mu g Se/liter (P = 0.05) for a single measurement. Total urinary selenium concentrations and urine volumes of 24-h samples from 28 healthy adult subjects on self-selected diets and living in San Angelo, Texas were measured. Daily total urinary excretions of 16 male and 12 female subjects (mean +/- SD) were 28 +/- 26 and 34 +/- 25 mu g Se/day, respectively. A single subject taking 300 mu g Se/day in the form of aqueous SeO2 as a dietary supplement excreted 232 mu g Se/day. The unsupplemented subjects' daily selenium excretions correspond to a mean dietary intake of approximately 60 mu g/day. (C) 1994 Academic Press, Inc.