Rapid acid leaching and slurry sampling procedures for the determination of methyl-mercury and total mercury in human hair by electrothermal atomic absorption spectrometry

The use of the slurry sampling technique was applied for the determination of total mercury in human hair by electrothermal atomic absorption spectrometry (ETAAS). In addition, an acid leaching procedure with hydrochloric acid was developed in order to determine Me-Hg+ in human hair with ETAAS. Palladium reduced by ascorbic acid was found to be adequate as a chemical modifier for both total mercury determination in hair slurries and methyl-mercury determination in hydrochloric acid solutions, at concentrations of 20 and 50 mg l(-1) for palladium and ascorbic acid, respectively. The acid leaching procedure was carried out by mechanical stirring with hydrochloric acid at 4%, and a leaching time of 2 min was selected. The limits of detection were 0.04 and 0.10 mu g g(-1) for methyl-mercury and total mercury determination, respectively. The within-batch precision was between 1.8 and 8.8% for total mercury determination, and between 1.5 and 6.5% for methyl-mercury. The method was applied to 20 human hair samples from healthy people, and it was also applied to the CRM 397 human hair reference material, finding results that agree with the certified ones. (C) 1999 Elsevier Science B.V. All rights reserved.