Hydrogen selenide evolution-electrothermal atomic absorption method for determining nanogram levels of total selenium.

A hydrogen selenide (H2Se) evolution-electrothermal atomic absorption method is described for determining nanogram concentrations of total selenium (Se) in biological and environmental materials. A mixed acid digestion procedure is used to decompose organic material. Sodium borohydride, a redesigned hydride generator, and an electric-headed absorption tube are used for H2Se evolution and conversion to atomic Se. The method has a detection limit of 4 ng/mL and a sensitivity of 0.6 ng/mL, and is linear from 0 to 90 ng Se/mL. As determined on urine, water, and bovine liver, total and within-run precision had relative and standard deviation values of 5-17.2 and 5.5-12.6% respectively. Accuracy was established with 2 NBS and 3 EPA reference materials, and mean errors of 0 to +0.8 were obtained. Mean recoveries of 109 and 101% were obtained for 10 and 50 ng Se added to human urine.