Direct determination of copper and lead in sewage sludge by solid sampling-graphite furnace atomic absorption spectrometry - study of the interference reduction in the gaseous phase working in non-stop flow conditions

Graphite furnace atomic absorption spectrometry is most useful for the dete rmination of metals in solid samples when samples with a slow or complicate d dissolution process are used. Its application to inorganic matrixes (espe cially geological material), therefore, appears to be a field of great inte rest. However, most of the papers published to date deal with organic sampl es, In the present paper two different strategies for the direct determinat ion of metals in inorganic samples are proposed depending on the relationsh ip between the analyte atomization temperature and the vaporization tempera ture of the matrix. For the more complicated case where both temperatures a re similar, working in non-stop flow conditions is proposed because it perm its a considerable reduction of interferences in the gas phase. This way th e determination of lead and copper in a sewage sludge sample was carried ou t. The results can be considered as satisfactory with regard to both accura cy and precision (R.S.D. of 7.8% and 5.7%, for Pb and Cu, respectively), as they are similar to previous ones obtained for mainly organic less problem atic samples. (C) 2000 Elsevier Science B.V. All rights reserved.