Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Methods were determined for lead and tin determinations in river, marine and lake sediments by slurry sampling and graphite furnace atomic absorption spectrometry. The optimizations were carried out using River Sediment BCR 320 and Marine Sediment PACS-2 for Pb and Sn, respectively. For Pb determination, the parameters studied included inorganic acid mixture, stabilizing agent, sample mass and sonication time. The influence of diluents and the extraction to the liquid phase for two different matrices was evaluated for Sn. The Pb content in the slurry liquid phase was ca. 56%, and ranged from 75% to 100% for Sn. Representative masses of 34 and 45 mg, and effective masses of 12 and 48 mu g for Pb and Sn, respectively, were obtained under optimized conditions. Detection and quantification limits of 0.2 and 0.7 mu g g(-1) for Pb, and 1.5-2.6 and 4.5-7.6 mu g g(-1) for Sn were obtained.16441732445451Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Financiadora de Estudos e Projetos (FINEP, Rio de Janeiro, Brazil)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [05/52975-9]