Determination of cadmium, copper and lead in mineral coal using solid sampling graphite furnace atomic absorption spectrometry

Solid sampling graphite furnace atomic absorption spectrometry (SS-GF AAS) was investigated as a potential technique for the routine determination of trace elements in mineral coal and cadmium, copper and lead were chosen as the model elements. Cadmium and lead could be determined at their main reso nance lines at 228.8 nm and 283.3 nm, respectively, but an alternate, less sensitive line had to be used for the determination of copper because of th e high copper content in coal. No modifier was necessary for the determinat ion of copper and calibration against aqueous standards provided sufficient accuracy of the results. For the determination of cadmium and lead two dif ferent modifiers were investigated, palladium and magnesium nitrates in sol ution, added on top of each sample aliquot before introduction into the ato mizer tube, and ruthenium as a 'permanent' modifier. Both approaches gave c omparable results, and it is believed that this is the first report about t he successful use of a permanent chemical modifier in SS-GF AAS. Calibratio n against solid standards had to be used for the determination of cadmium a nd lead in order to obtain accurate values. The agreement between the value s found by the proposed procedure and the certificate values for a number o f coal reference materials was more than acceptable for routine purposes, T he detection limits calculated for 1 mg of coal sample using the 'zero mass response' were 0.003 and 0.007 mug g(-1) for cadmium with the permanent mo difier and the modifier solution, respectively, approximately 0.04 mug g(-1 ) for lead, and 0.014 mug g(-1) for copper. (C) 2001 Elsevier Science B.V. All rights reserved.