Determination of lead, copper, manganese and zinc in botanic and other biological samples by electrothermal atomic absorption spectrometry using scandium-containing chemical modifiers

The use of Sc, Ru, Sc + (NH4)2HPO4, Ru + (NH4)2HPO4, Sc + Ru and Sc + Ru + (NH4)2HPO4 as chemical modifiers has been comprehensively investigated for the direct determination of trace elements such as lead, copper, manganese and zinc in botanic and biological samples using electrothermal atomic absorption spectrometry (ETAAS). Effects of mass and mass ratio of modifiers on analytes in sample solutions have been studied. Optimum mass and mass ratio of modifiers found are 20 (mu)g Sc, 4 (mu)g Ru, 50 (mu)g (NH4)2HPO4 and 20 (mu)g Sc + 4 (mu)g Ru + 50 (mu)g (NH4)2HPO4. Pyrolysis and atomization temperatures, atomization and background profiles, detection limits and characteristic masses of analytes in the presence or absence of modifiers have been comprehensively investigated and compared. The detection limits and characteristic masses obtained with Sc + Ru + (NH4)2HPO4 modifier mixture are 0.72 (mu)g l^-1 and 16.3 pg for Pb, 0.32 (mu)g l^-1 and 5.6 pg for Cu, 0.09 (mu)g l^-1 and 0.1 pg for Mn, and 0.03 (mu)g l^-1 and 1.1 pg for Zn, respectively. The proposed Sc + Ru + (NH4)2HPO4 modifier mixture in Triton X100 0.5% (v/v) plus nitric acid 0.2% (v/v) mixture as diluent has been applied for the determinations of Pb, Cu, Mn and Zn in certified and standard botanic and biological reference materials. The results obtained are in good agreement with the certified values.