DETERMINATION OF TRACE IMPURITIES IN HIGH-PURITY QUARTZ BY INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY

Inductively coupled plasma mass spectrometry was employed for the determination of trace amounts of Li, B, Mg, Cr, Mn, Ni, Co, Cu and Zr in high-purity quartz. The effects of mannitol, dulcitol and sorbitol on the suppression of B volatilization during sample decomposition with hydrofluoric acid and evaporation to dryness were examined. The volatilization of B was found to be completely suppressed by the addition of more than 1.5 mg of dulcitol or more than 3.0 mg of mannitol, while even 3.5 mg of sorbitol was insufficient for the complete suppression. Thus, the addition of 2.0 mg of dulcitol, which was most effective for the complete suppression of B volatilization, was selected. Signal loss and spectral interference on the introduction of the solutions containing the organic compounds into the inductively coupled plasma mass spectrometer were examined. Continuous operations were possible for 3h without signal loss due to carbon deposition on the sampling cone orifice when the solution containing 2.0 mg of dulcitol was introduced. Spectral interference from (ArC)-Ar-40-C-12 on Cr-52 occurred in the presence of 2.0 mg of dulcitol. Therefore, the measurements were performed by dividing the elements into two groups: one group for Li, B and Mg determination, and the another for Cr, Mn, Ni, Co, Cu and Zr determination. Dulcitol was not added in the latter case. The detection limits (3sigma) obtained with the present method were 0.0005-0.01 ppm.