Selenium determination in biological fluids using Zeeman background correction electrothermal atomic absorption spectrometry

Procedures for the direct determination of total selenium in urine, serum, and blood using electrothermal atomic absorption spectrometry are presented . In the selected experimental conditions, Zeeman correction is mandatory t o compensate for the high background signals. The sample diluted and contai ning 0.1% (w/v) Triton X-100 is introduced directly into the electrothermal atomizer. A solution containing 15% (w/v) hydrogen peroxide, 0.65% (w/v) n itric acid, and 0.5% (w/v) nickel is injected separately into the atomizer. Calibration is carried out using the standard additions method. The detect ion limit is 30 pg selenium. If palladium, instead of nickel, is used as th e chemical modifier, calibration can be carried out against aqueous standar ds, and the detection limit is 46 pg. In this case, three separate injectio ns are required to prevent precipitation problems in the automatic injector . The reliability of the procedures is checked by analyzing three certified reference materials and by recovery studies. Mean recoveries are 99.7% for serum, 99.4% for urine, and 100.8% for blood samples. Relative standard de viation values are +/-4.0% for serum, +/-3.9% for urine, and +/-4.5% for bl ood. (C) 2000 Academic Press.