Determination of selenium in urine by hydride generation atomic absorption spectrometry

A procedure has been developed for determination of total selenium in urine by hydride generation atomic absorption spectrometry. Mineralization was performed with a nitric acid-perchloric acid mixture on a thermostated digestion block. The method was validated by comparison with the method involving mineralization in a microwave acid digestion bomb containing nitric acid and small amounts of vanadium pentoxide. Se(VI) was reduced to Se(IV) by dissolution in 7N HCl. Sample recoveries, precision studies, and analyses of a certified reference material demonstrated the reliability and accuracy of this technique. Urine samples had selenium concentrations ranging from 4.6 to 50.3 micrograms/L. These values correspond to an average of 54.9 micrograms per person per day total ingested and bioavailable Se in the daily diet.