MON SPECTRAL INTERFERENCES ENCOUNTERED WITH A COMMERCIALLY AVAILABLE HIGH-RESOLUTION ICP MASS-SPECTROMETER

Results of a systematic study concerning non-spectral interferences ob served with a commercially available high resolution ICP-mass spectrom eter are reported and compared to observations made with a quadrupole- based instrument. In general, matrix effects were observed to be to a large extent comparable for both instruments used. In all cases, the m atrix-induced signal suppression or enhancement was seen to depend in a regular way on the mass number of the nuclides monitored. In most ca ses, the ionization potential of the nuclides has little or no influen ce on the extent of suppression or enhancement. For As, Se and Te, the introduction of 2.5 % ethanol, 0.5 mol/l H2SO4, or to a lesser extent 0.5 mol/l H3PO4, leads to an exceptional increase in the signal inten sity for both instruments. Registration of signal behaviour plots (sig nal intensity as a function of the nebulizer gas flow rate) in differe nt matrices revealed that both the height of the plot and the optimum nebulizer gas flow rate are a function of the matrix composition. Fina lly, no indication was found that the acceleration of the extracted io ns over 8000 V with the high resolution instrument would lead to an al leviation of space charge effects when compared to a quadrupole-based ICP-mass spectrometer.