Analysis of silicon dioxide and silicon nitride powders by electrothermal vaporization inductively coupled plasma atomic emission spectrometry using a tungsten coil and slurry sampling

Slurry sampling in combination with ETV-ICP-AES was employed for the direct determination of trace amounts of impurities in silicon dioxide and silicon nitride. The ETV device consisted of a double layer tungsten coil in a quartz apparatus. Spectral interferences and background emission caused by tungsten ablation of the coil were reduced by coating the coil with tungsten carbide. The background was measured either with a high-purity sample, the suspension medium or close to the analyte emission line, depending on matrix and analyte, or it was calculated using relative emission intensities of tungsten. The concentrations of Al, B, Be, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb and Zn were measured simultaneously, whereas K and Na were determined in the sequential mode. Calibration was performed using the standard additions method. The accuracy was checked by comparison with the results of independent methods. Limits of detection between 0.035 (Mg) and 130 mu g g(-1) (B) and between 0.01 (Be, Mg) and 34 mu g g(-1) (B) were achieved in silicon dioxide and silicon nitride, respectively.