ADDITION OF SMALL AMOUNTS OF HELIUM AND HYDROGEN TO THE WORKING GASESIN SLURRY NEBULIZATION INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRY FOR THE ANALYSIS OF CERAMIC POWDERS

Small amounts of hydrogen and helium were added to the internal gas fl ow of a 1.5 kW inductively coupled argon plasma to investigate the cap abilities of the resulting mixed gas plasmas with respect to the parti cle evaporation in slurry nebulization inductively coupled plasma atom ic emission spectrometry for the analysis of refractory ceramic powder s. The addition of up to 15% v/v of hydrogen to the internal gas resul ts in an increase in the Al and Si line intensities for slurries of Al 2O3 and SiC powders of up to 20-100%, after optimization of all parame ters. The corresponding increases in the recoveries were found to be o f the order of 9-14% for Al2O3 and SiC powders with sizes of 0.3-18 an d 0.3-12 mu m, i.e., from 48 to 62% and from 43 to 52%, respectively. Additions of helium, however, were only 50% as efficient. These effect s refer to a more efficient evaporation of the powders in the plasma. Axially resolved measurements of analyte line intensities for both slu rries and solutions also reflect the influence of the amounts of added hydrogen helium on the plasma geometry.