ELEMENT DETERMINATIONS IN AQUEOUS AND ACETONITRILE CONTAINING SOLUTIONS BY ATOMIC-EMISSION SPECTROMETRY USING A MICROWAVE PLASMA TORCH

The analytical performance of the microwave plasma torch (MPT) as a ra diation source for atomic emission spectrometry in the case of sample introduction of liquids by pneumatic nebulization using a Legere nebul izer was investigated. Aerosol loading by either water or acetonitrile (AcN) did not disturb the plasma discharge stability. The addition of Cs or AcN to aqueous solutions leads to a signal suppression in the c ase of Cd, Cr and Pb and a signal enhancement in the case of Li for co ncomitant concentrations of about 50 mu g ml(-1) onwards. For aqueous solutions, the limits of detection of Cr, Cd and Pb are on the order o f 0.1-1 mu g ml(-1) and 5-20 ng ml(-1) for Li. For Cr, dissolved as am monium pyrrolidinedithiocarbamate (APDC) complex in an AcN/H2O mixture (2:1), the detection limit is 0.1 mu g ml(-1). When AcN is present in the aerosol, spectral background records show that the wavelength ran ge in which atomic emission lines are free from interferences is limit ed as a result of strong molecular band emission spectra, especially b etween 350 and 430 nm. (C) 1998 Elsevier Science B.V. All rights reser ved.