Determination of chromium in serum by electrothermal atomisation atomic absorption spectrometry using totally pyrolytic graphite cuvettes

Abstract

Uncoated, pyrolytic graphite coated and totally pyrolytic graphite (TPG) cuvettes were compared as electrothermal atomisers for the determination of chromium by atomic absorption spectrometry. The TPG cuvettes provided superior sensitivity (0.86 pg) and were used for the measurement of chromium in serum. Sample dilution (1 + 1) with 0.1%m/V Triton X-100 in 0.1%V/V nitric acid gave the best combination of sensitivity, reproducibility and low blank compared with other diluents. The absence of non-atomic absorption was shown by measurements at 358.5 nm using a uranium hollow-cathode lamp. No non-specific absorbance was detected and background correction was not used. The reproducibility within batch was 4.8 and 2.8% at 1.1 and 10.0 µg l^–1, respectively, and 9.7 and 8.0% at 0.46 and 4.4 µg l^–1, respectively, between batch. Calibration with matrix-matched standards was used except for anomolous specimens (uraemic sera with high chromium concentrations) where standard additions were found to be essential. Specimens of sera from 20 healthy adults, collected to avoid contamination, contained chromium concentrations of up to 0.45 µg l^–1.