Electrothermal atomic absorption spectrometry determination of molybdenum in whole blood

Abstract

A method for the determination of molybdenum in whole blood by atomic absorption spectrometry with electrothermal atomization was developed and evaluated. Erbium (25 μg) was chosen from several potential chemical modifiers (Sm, Lu, Ho, Eu and Pd+Mg) as the most appropriate for the sensitive and reliable determination of molybdenum in such sample. The process used was direct dilution of the sample in a ratio 1:2 with a 0.1% (v/v) Triton X-100 solution. The injection of 20 μl of a solution of 15% (w/v) hydrogen peroxide and running the temperature program after 5 firings greatly reduced the effect of build-up of carbonaceous residues within the atomizer. The limit of detection and working ranges, respectively, were 0.6 and 2.0–100.0 μg l −1, and the characteristic mass was 7.2 pg. The relative standard deviation varied from 0.8 to 1.5% for within and between batch determinations, respectively. The determination of molybdenum in Seronorm™ Trace Elements in Whole Blood with known added amounts of the analyte was performed to asses the accuracy. The optimized procedure has been applied to the determination of molybdenum in whole blood specimens of 20 subjects taken before and 10–12 h after receiving an over-supply of 1 mg of molybdenum. The molybdenum concentrations (±S.D.) were 10.9±0.4 μg Mo l −1 (range 9.9–11.6 μg Mo l −1) and 15.4±0.4 μg Mo l −1 (range 13.1–16.9 μg Mo l −1) for the individuals before and after the administration of molybdenum.