AN INVESTIGATION OF DIFFERENT MODIFIERS IN ELECTROTHERMAL VAPORIZATION INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY (ETV-ICP-MS)

The suitability of eleven modifiers (Pd-, Mg-, K-, Ca-and NH4-salts) f or electrothermal vaporization coupled to inductively coupled plasma m ass spectrometry (ETV-ICP-MS) for the determination of Mn, Cu, Zn, Cd and Pb has been studied. Solutions containing varying quantities (10-2 000 ng absolute) of these salts have been added to four different amou nts of analyte to study their suitability as modifier and their mass d ependent influence. The best sensitivity enhancement for all elements tested was achieved with IrCl3 and PdCl2. From a comparison of the eff ect of PdCl2 vs. Pd(NO3)(2) it could be concluded that the mechanism o f matrix modification also depends on the chemical form of the modifie r. Particularly, for the volatile elements Cd and Zn differences in th e behavior of the different chemical compounds of one metal (e.g. Pd) is evident, which shows that the enhancement effect is a result of the stabilization of the analytes in the graphite tube prior to vaporizat ion and the improvement of the transport efficiency after vaporization .