Microwave-assisted volatilization of chlorides of Ge and Se for the determination of trace impurities in high purity Ge and Se by ICP-MS

Abstract

Closed-vessel microwave assisted volatilization of Ge and Se as their chlorides in the presence of vapors of HCl and HNO3, for the determination of trace impurities in high purity Ge and Se, is reported. The volatilization of Ge is 98.7% using vapor of aqua regia whereas vapor generated from a 72∶1 ratio of HCl:HNO3 is required to volatilize 99.2% of Se. The recoveries of Mg, Cr, Mn, Fe, Ni, Co, Cu, Zn, Ag, Cd, Ba and Pb are in the range 91–107%. Determinations are carried out using an inductively coupled plasma mass spectrometer with a Dynamic Reaction Cell™ (DRC ICP-MS). Isobaric interferences, due to the formation of 40Ar12C+, 35Cl16OH+, 40Ar16O+ and 40Ar74Ge+ on the determination of 52Cr+, 56Fe+ and 114Cd+, have been alleviated using ammonia cell gas in DRC. Matrix volatilization using in situ generated acid vapors in closed containers resulted in sub ng mL−1 experimental blanks. Method detection limits are in the low ng g−1 level. The methods developed have been applied to the determine trace impurities in high purity Ge and Se samples (>99.999% purity).