Slurry sampling for hydride generation atomic absorption spectrometric determination of arsenic in cigarette tobaccos

The development of a slurry sampling hydride generation atomic absorption spectrometric (HGAAS) method for the determination of arsenic in cigarette tobacco samples is described. The method is relatively simple and has been shown to give values of total arsenic close to those obtained using methods requiring total dissolution and decomposition of all vegetable matter before analysis. Pre-treatment of samples slurried in nitric acid by ultrasonication permitted the extraction of about 90% of the total arsenic from tobacco samples. Further improvement in the recovery efficiency (up to 93-94%) was accomplished by the use of an additional step of short microwave-accelerated treatment. L-Cysteine was used as a pre-reduction agent. The accuracy and precision of the slurry sampling HGAAS method were studied using the certified reference material (CRM) CTA-OTL-1 Oriental Tobacco Leaves. Under the optimum conditions, as little as 2.6 ng of arsenic can be detected. The relative standard deviation of the overall procedure was calculated to be below 7.6% at arsenic concentration levels of 0.5-0.9 mg kg-1 and the analytical results obtained for the CRM agreed with the certified value. The main factors that influenced the reliability of the method were sample homogeneity, particle size and slurry concentration.