Determination of Trace Impurities in High-purity Quartz by Electrothermal Vaporization Inductively Coupled Plasma Mass Spectrometry Using the Slurry Sampling Technique

Abstract

A method has been developed for the determination of 14 relevant trace impurities in high-purity quartz based on ETV-ICP-MS using slurry sampling. The ETV device consisted of a double layer tungsten coil. Experimental conditions were optimized with respect to the temperature program, the carrier gas flow, the i.d. of the aerosol tubing, ICP-MS measurement parameters and internal standardization. Excluding U, calibration had to be carried out by the standard additions method because of non-spectral matrix interferences. For U, simple quantification via calibration curves, recorded with aqueous standards, was possible. The observed interferences also aggravated the background evaluation, which seriously limited the determination of Al and Fe. The method was applied to the determination of Al, Ba, Co, Cr, Cu, Fe, Li, Mg, Mn, Na, Pb, Sr, U and Zn in two quartz samples of different grades of purity. The accuracy of the results was checked by their comparison with those obtained by independent methods including instrumental neutron activation analysis. The achievable detection limits are between 2 ng g ^-1 (Li, U) and 70 µg g ^-1 (Al).