Improved determination of vanadium in biological fluids by electrothermal atomic absorption spectrometry.

We made sensitive and accurate electrothermal atomic absorption spectrometric measurements of vanadium in small volumes of serum. The wet-digested sample was extracted into an organic solvent, with N-benzoyl-N-(o-tolyl)hydroxylamine (BTA) as the chelating reagent. After evaporating the solvent, we dissolved the residue in acetic acid, and injected a 60-microL aliquot into a graphite furnace. In this way we could measure vanadium concentrations as low as 80 ng/L in 4 mL of serum. The within-run CV was 3.3% for serum, 7.7% for urine. Analytical recoveries of vanadium added to serum and urine were 90.3% and 90.8%, respectively. We measured vanadium concentrations in sera from 64 healthy persons (group 1), 15 nondialyzed uremic patients (group 2), and 11 hemodialyzed patients (group 3). The highest concentration of vanadium in group 1 was 240 ng/L; about 60% of the values for this group were less than 80 ng/L. In group 3, the vanadium concentrations were extremely high (15 +/- 14.2 micrograms/L, mean +/- SD), less so (but still above normal) in group 2 (1.58 +/- 3.16 micrograms/L).