Laser ablation and low-pressure helium-ICP-MS for the analysis of alumina powder dispersed in glycerol.

A combined method of laser ablation (LA) and ICP-MS has gained much attention as a direct analytical method for solid samples. The determination of some elements, however, is seriously disturbed by isobaric interferences, mainly caused by argon and ambient air constituents. The use of low-pressure helium-ICP is a promising solution of the problem. A 1:1 mixture of alumina powder and glycerol was deaerated and irradiated with a pulsed laser beam (150 mJ) for 10 s. The sample aerosol was transported to the ICP with a stream of helium. Indium was used as an internal standard for correcting the ablated sample amount. Calibration curves were prepared from glycerol containing high-purity alumina, trace metals and indium. The detection limits for Cr, Mn, Fe, Co, Ni, and Cu approached the fractional ppm levels. The proposed method was successfully applied to the analysis of different alumina samples (99 - 99.995% purity).