REDUCTION OF SOME SELECTED SPECTRAL INTERFERENCES IN INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY

The reduction of spectral interferences has been investigated and both aerosol desolvation and the utilization of high mass resolution have been applied in order to improve detection limits for V, Cr, Ga, Ge an d As, which are subject to interferences by polyatomic ions in solutio ns containing Cl. Experiments with a laboratory-made quadrupole ICP-MS have been performed in order to optimize the desolvation parameters. Ion signals corresponding to ClO+ and ClOH+ are reduced by more than o ne order of magnitude if appropriate heating and cooling temperatures are chosen. A reduction in polyatomic ions like ClO2+, Cl2+ and ArClby using desolvation was also observed. With the prototype of a new do uble-focusing ICP-MS system from Finnigan MAT, Bremen, Germany, operat ed in the low resolution mode, the detection limits with desolvation h ave been determined and were found to be up to 2 orders of magnitude l ower compared with measurements without desolvation. The detection lim it (3s) for V in 0.4 mol l-1 HCl was reduced from 25 to 1 ng ml-1. Hig h mass resolution improved the detection limits for V, Cr and Ga in HC l by up to 4 orders of magnitude compared with measurements in the low resolution mode (2 pg ml-1 for V in 0.4 mol 1(-1) HCl), and lowest de tection limits have been obtained with the combination of desolvation and high mass resolution (0.6 pg ml-1 for V in 0.4 mol l-1 HCl).