Determination of cobalt in urine by flameless atomic absorption spectroscopy. Comparison of direct analysis using Zeeman background correction and indirect analysis using extraction in organic solution.

Urinary cobalt was determined by flameless atomic absorption spectroscopy. Three methods were compared: direct analysis with deuterium background correction after 11-fold dilution with distilled water (method D), analysis with deuterium background correction after extraction of cobalt from the urinary matrix in organic solution (method E), and direct analysis with Zeeman background correction (method Z). The detection limit of the direct analysis of urinary cobalt with deuterium background correction was 6 micrograms/L, this appeared to be insufficient for the determination of reference values and moderate enlarged cobalt values. Comparison of the extraction method and the Zeeman method revealed that these methods have similar reference values, detection limits, precision and recovery.