Slurry sampling electrothermal atomic absorption spectrometry as screening method for chromium in compost

Ultrasonic slurry sample introduction was applied to the determination of total chromium in composted materials by electrothermal atomic absorption spectrometry (ETAAS). The effect of grinding on the heterogeneity of the test samples and on the attainable precision was studied. The repeatability was influenced by the heterogeneity of the test samples at the μg-level, the R.S.D. of the measurements being 15%. The reproducibility depended on the heterogeneity of the test sample at the mg level, and it could be improved from 11 to 7% by increasing the grinding time. The characteristic mass was 2.6 pg and the detection limit for the optimised procedure at the 0.04% (w/v) slurry concentration, 370 ng g−1. Good agreement with a certified reference material and with the conventional microwave assisted digestion method was found by using external calibration with aqueous standards. The performance of the method for screening purposes was evaluated.