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Journal of the Brazilian Chemical Society
versión On-line ISSN 1678-4790
BORGES, Daniel L. G.; DIAS, Lúcia F.; VEIGA, Márcia A. M. S. da y CURTIUS, Adilson J.. Determination of cadmium in sediments and in sewage sludge by slurry sampling electrothermal atomic absorption spectrometry using iridium as permanent modifier. J. Braz. Chem. Soc. [online]. 2003, vol.14, n.2, pp. 291-296. ISSN 1678-4790. http://dx.doi.org/10.1590/S0103-50532003000200017.
A procedure for the determination of Cd in sediment and sewage sludge as slurries by electrothermal atomic absorption spectrometry is proposed. The slurry, 1 mg mL-1, was prepared by mixing sample ground to a particle size £ 50 mm with 5% v/v nitric acid in an ultrasonic bath. The homogeneity of the slurries was assured by passing a constant flow of argon into the autosampler cup, just before transferring an aliquot to the graphite furnace. Two permanent modifiers deposited on the platform were tested: Ru and Ir. Modifiers in solution were also tested: Pd plus Mg and phosphate alone or plus Mg. The Ir-treated tube was adopted due to its good performance as modifier and also for practical reasons. About 80% of Cd is extracted to the water phase of the slurry. To test the accuracy of the method, three certified materials were analyzed: a marine sediment, a river sediment and a domestic sewage sludge. The concentrations obtained, using calibration against aqueous standards prepared in the same medium as the slurries, are in agreement with the certified values, at a confidence level of 95%, according to the Student-t test. The limit of detection (3s) was 43 ng g-1 in the solid sample and the relative standard deviation for the sediment MESS-2 was 2.3% (n = 10).
Palabras clave : cadmium, slurry; ET AAS; modifier; sediment; sewage sludge.