Analysis of silicon carbide powders with ICP-MS subsequent to sample dissolution without and with matrix removal

ICP-MS has been employed for the analysis of silicon carbide powders in connection with high pressure acid decomposition without and with matrix removal by evaporation. The powder is decomposed by treatment of a 250 mg sample with a mixture of HNO3, H2SO4 and HF. Prior to the analyses with ICP-MS the solutions have to be diluted to a matrix concentration of 500 μg/ml related to SiC in order to realize full long-term precision. The results obtained for Li, B, Na, Mg, Al, Ca, Sc, Ti, V, Cr, Mn, Fe, Ni, Co, Cu, Zn, Ga, Sr, Y, Zr, Nb, Ag, Cd, In, Sn, Sb, Ba, La, Ce, Pr, Nd, Hf, Ta, W, Tl, Pb, Bi, Th and U in SiC powder S-933 are shown to be in good agreement with those of independent methods, such as INAA, ICP-AES with slurry atomization and ICP-AES subsequent to sample decomposition. For extending the use of ICP-MS to elements such as Mg, Ca, Sc and Ti at the relevant concentrations in SiC powders, a more effective matrix removal by evaporation of the decomposition solution to near dryness has been successfully applied. Its advantages have been proven by the results of high resolution ICP-MS. It has been found by analyses of the treated sample solutions for the residual Si and C with ICP-MS that over 99% of the matrix and also of the acids used for decomposition are removed. For B, Al and Fe losses were found to occur at concentration levels of some μg/g, 200 μg/g and 300 μg/g, respectively, and all other elements were detected with very good recoveries. For all 36 elements investigated in this work the detection limits could be improved from the ng/g to the pg/g range by removal of the matrix. The analytical range could be improved, in particular for In, Tl, Bi and U.