DETERMINATION OF ARSENIC IN MUSSELS BY SLURRY SAMPLING AND ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY (ETAAS)

A method for the determination of arsenic in slurries of mussel tissue using palladium-magnesium nitrate as modifier was optimized. The slurry was stabilized by a 0.015% (v/v) of Triton X-100. To achieve complete mineralization the slurries were ashed at 480 degrees C for 10s in an air flow (50 ml/min) and at 1200 degrees C for 15s in an argon flow (300 ml/min) in the presence of Pd-Mg(NO3)(2) as modifier. The optimum atomization temperature was 2200 degrees C. The precision and accuracy of the method were studied using the Reference Material BCR no 278 Mussel Tissue (Mytilus edulis). The detection limit (LOD) of the final slurry solution was 1 mu g/l of arsenic corresponding to an arsenic level in the mussel of 1.3 mu g/g, for a 0.5% (m/v) slurry. Results of calibration using aqueous standards and the standard additions method were compared. The method was applied to the determination of arsenic in mussels from the Galician coast. The levels found lie between 2 and 9.3 mu g/g of arsenic.