COMPARATIVE-STUDIES OF SURFATRON AND MICROWAVE PLASMA TORCH SOURCES FOR DETERMINATION OF MERCURY BY ATOMIC-EMISSION SPECTROMETRY

Two cavities are compared for the determination of mercury with aqueou s sample introduction by an ultrasonic nebulizer. The performances of the cavities, surfatron and microwave plasma torch (MPT), are compared , with particular emphasis on the characteristics of plasma features, the effects of operational conditions, tolerance to foreign material o r the presence of other elements, and analytical figures of merit. The effect of potassium chloride and ammonium chloride on the analytical performance of MIP (surfatron)-AES and MPT-AES has been examined and a possible mechanism is discussed. An improvement of about 3-fold in de tection limits was achieved by adding an appropriate amount of 0.05% m /v of ammonium chloride. The detection limits for mercury by surfatron AES and MPT-AES are 0.9 and 1.3 ng ml-1, respectively. The precision obtained in this work is below 2.0. Stable discharges were obtained in both cavities with use of a low-power microwave generator.