Microwave desolvation for acid sample introduction in inductively coupled plasma atomic emission spectrometry

This study deals with the behaviour of a microwave desolvation system (MWDS ) with acid solutions in inductively coupled plasma atomic emission spectro metry. Hydrochloric, nitric, sulphuric and perchloric acids at different co ncentrations (up to 0.6 mol l(-1)) have been tested. Sample uptake rate (Q( 1)) was also varied. The parameters evaluated for each variable were analyt e and solvent transport rates and emission intensity. The combination of lo w acid concentrations (0.05-0.1 mol l(-1)) and low liquid flows (0.4 mi min (-1)) leads to the highest analyte transport rate and emission signal and t o the lowest solvent transport rate. For Q(1) higher than 1.9 mi min(-1), t he use of an impact bead is advisable. Among the acids tested, sulphuric an d perchloric acids give rise to higher emission intensities than hydrochlor ic acid and nitric acid. Nonetheless, the limits of detection (LODs) obtain ed with the MWDS are about the same magnitude irrespective of the solution employed. The LODs reached when using the MWDS are similar to those obtaine d with a desolvation system based on infrared heating of the aerosol. (C) 1 999 Elsevier Science B.V. All rights reserved.