Comparative study of a beenakker cavity and a surfatron in combination with electrothermal evaporation from a tungsten coil for microwave plasma optical emission spectrometry (MIP-AES).
Microwave induced plasmas, sustained in a Beenakker resonator and a surfatron, respectively, are used to excite vapours released by electrothermal evaporation of solutions from a tungsten coil. The analytical figures of merit of AES for two easily volatilized elements (Cu, Cd) are compared for argon MIP operated in the two resonators under optimized conditions. In the Beenakker resonator a 1-filament plasma was produced at an argon flow of 0.45 l./min and a forward power of 50 W. In the surfatron a 2-filament plasma with 2.44 l./min argon and a forward power of 130 W was used. The detection limits for Cu and Cd with the surfatron are lower than those obtained with the Beenakker resonator and are in the range 10-20 ng/ml. Also interferences arising from an easily ionized element such as Na are lower with the surfatron than with the beenakker resonator. The linear dynamic ranges in the case of the surfatron are also superior and extend over three decades of concentration.
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Institut für Spektrochemie und angewandte spektroskopie (ISAS), Postfach 10 13 52 D-4600 Dortmund 1, FRG.
Broekaert
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Tschöpel
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Tölg
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