Abstract

A method is presented for the extraction of cadmium as the Cd(Ox) 2 complex with methanol-modified supercritical CO2. In a first step, aliquots of Cd2+ solutions were spiked onto filter paper and air-dried, and the filter paper with cadmium, oxine and methanol was placed in a 10ml stainless steel extraction vessel. A study was made of extraction as a function of pressure (6.9-24.1MPa), oven temperature (40-200°C), restrictor temperature (20-100°C), presence of modifier (1.0-4.0ml), and static extraction time (10-50min). Quantitative extractions of cadmium were achieved when the experiments were carried out at 17.2MPa, 80-120°C oven temperature, 60°C restrictor temperature, 2.0-3.0ml of methanol, 30min static extraction, and 5min in dynamic mode. An aliquot of the extract was placed in an electroanalytical cell that contained a supporting electrolyte, and cadmium was quantified by square wave stripping voltammetry. The calibration graphs using cadmium solutions in the presence of 0.1M of oxine were linear over a 5.0-120.0?gl-1 range. The detection limits using anodic stripping voltammetry or adsorptive stripping voltammetry were 1.5 and 1.4?gl-1 of cadmium, respectively. The efficiency of the extraction was evaluated using certified reference human hair. The procedure was then applied to cigarette samples and to hair of cigarette smokers and non-smokers. Cadmium concentration ranges were 0.06-0.57?gg-1 (average 0.25±0.18?gg-1) for smokers and 0.02-0.26?gg-1 (average 0.11±0.07?gg-1) for non-smokers. © 2003 Elsevier B.V. All rights reserved.