Determination of trace elements in carbonaceous samples by graphite furnace atomic absorption spectrometry: Microwave digestion versus slurry sampling

The determination of chromium, copper, manganese, nickel and vanadium in carbonaceous samples by slurry introduction graphite furnace atomic absorption spectrometry and after microwave assisted digestion are compared. Parameters such as atomization and pyrolysis temperatures, and surfactant concentration as well as the homogenization procedure were optimized. The slurries were prepared by mixing adequate amounts of the pulverized samples with 0.05% Triton X-100, sonicating for, at least, 40 seconds during the preparation to separate aggregates and for 20 seconds immediately before being autosampled. It was not necessary to use modifiers and calibration against aqueous standards was possible for all the elements. Coke, graphite and certified coal samples were analyzed, and no significant difference was observed using both procedures. Good agreement between found and certified values was obtained.