Methods for the determination of manganese and nickel in lake and marine sediment slurries by graphite furnace atomic absorption spectrometry using permanent modifiers are proposed. The slurries were maintained homogeneous with air bubbling with an aquarium pump. For manganese, the best modifier was ruthenium permanent with mo of 0.9 pg and of 1.0, 1.2, 1.5, and 1.8 pg, for Rh, without modifier, Ir, and Zr, respectively. For nickel, the best modifier was rhodium permanent with mo of 33 pg, followed by 85, 120, 132, and 240 pg, without modifier, Zr, Ir, and Ru, respectively. After determining manganese and nickel in two certified marine sediment samples (n = 10) from NRCC, PACS-2, and MESS-2, and in the San Joaquin 2079 soil, the results agreed at the confidence level of 95% with the certified value for all analytes studied using aqueous calibration. Calibration curves of all analytes had correlation coefficients R2 higher than 0.99. Recovery studies made in four levels for each analyte in sediments from Lake Pampulha showed acceptable values. The limits of detection (LODs) were 4.0 and 0.9 µg L-1 for manganese and nickel, respectively.Key words: manganse, nickel, sediments, GF AAS.
