MICROSAMPLE INTRODUCTION BY TUNGSTEN FILAMENT ELECTRODE INTO CAPACITIVELY COUPLED MICROWAVE PLASMA FOR ATOMIC EMISSION-SPECTROSCOPY - ANALYTICAL FIGURES OF MERIT

A tungsten filament electrode for sample introduction into a capacitively coupled microwave plasma (CCMP) is described for its use in atomic emission spectroscopy (AES). Samples vaporize rapidly off the filament and are excited in the microwave plasma upon the initiation of the microwave discharge. The maximum emission signals of He and Cu were found at similar spatial coordinates, gas flow-rates and microwave powers. The addition of 100 ml min-1 hydrogen dopant into the plasma gas suppressed both the background and emission from the tungsten. The filament temperature increased with the power. The absolute detection limits of 12 elements were within the range of 1 to 100 pg. The linear dynamic range was 3-4 orders of magnitude, and precision was better than 10%.