Determination of cobalt in plasma and urine by electrothermal atomisation atomic absorption spectrometry using palladium matrix modification

Abstract

The determination of cobalt in plasma and urine samples by ETA-AAS is reviewed and a modified assay described. The use of ammonium phosphate and Pd as matrix modifiers is compared; Pd is preferred because it permits the use of higher ashing temperatures. The sample is pre-mixed with a concentrated modifier solution containing Pd, Triton and antifoam. Deuterium arc background correction is used. The limit of detection of the assay is 0.15 µg l^–1 of Co. Sample collection procedures for plasma were investigated and the use of stainless-steel needles and standard Li-heparin containers was found to be adequate for the detection of elevated concentrations in the patients studied. The normal range of Co concentrations in plasma was found to be 0.35 ± 0.15 µg l^–1. In patients with chronic renal failure on maintenance haemodialysis the concentrations found were 1.46 ± 0.57 µg l^–1.