Determination of selenium in human urine by electrothermal atomic absorption spectrometry

A GFAAS method for the direct determination of selenium in humane urine has been presented. Mixed Pd, Rh and Ir were thermally reduced and electrodeposited as modifiers. Also an alternating air stream was used during the pyrolysis. The influence of modifiers (Pd, Rh and Ir) on the maximum pyrolysis temperature, sensitivity, background absorption and atomization signal shape were studied. Optimum performance of the method was achieved in the presence of thermally reduced Rh. Under optimum experimental conditions (pyrolysis in air at 300 degrees C, pyrolysis in argon at 1300 degrees C, and atomisation at 2200 degrees C) detection limit (expressed as three times the standard deviation of 1.0% (v/v) HNO3 solution) was 7.5 +/- 1.2 mu g L-1 for the 20 mu L-in-volume sample. Characteristic mass was found to be 4.3 pg and 6.8 pg for aqueous standards and urine solutions, respectively.