Investigation of the interactions of a microwave-induced plasma with a quartz capillary wall

Emission intensities of Si and He in a microwave-induced plasma were measured as functions of axial position, He flow rate, and microwave power. The changes in these intensities which accompany plasma-wall contact are described. The conditions required for the plasma to contact the wall of the quartz capillary tube were established, and the vaporization of residues from aqueous metal solutions from the quartz surface was examined. Residues from solutions of Cd, Cu, Pb, Sn, and Zn deposited in the capillary were vaporized and excited by the plasma, and the integrated atomic emission signals produced linear calibration curves from 0.1 to 100 ppm for 1.8 ..mu..L injections. The precision for a 0.5 ppm Cd solution was 4.9% (RSD).