ISOTOPE RATIO MEASUREMENT BY INDUCTIVELY-COUPLED PLASMA MULTIPLE COLLECTOR MASS-SPECTROMETRY INCORPORATING A HIGH-EFFICIENCY NEBULIZATION SYSTEM

Isotope ratio analysis by inductively coupled plasma multiple collector mass spectrometry has been performed utilizing a high efficiency desolvating nebulization system for sample introduction. The high accuracy and high precision analysis of uranium, lead and hafnium reference materials at a concentration of 50 ng ml-1 are reported. Use of the high efficiency device has increased sample transmission and hence increased ion-signal levels by a factor of ten compared with conventional nebulization. The analysis of each uranium and lead solution required 29 ng of sample while the analysis of each hafnium solution required 290 ng of sample. The accuracy and precision of the measurements are comparable with those obtained by thermal ionization mass spectrometry. Transmission calculations indicate an ion: atom ratio of 1:5500 for each of the three elements. This is superior to that observed with other plasma source mass spectrometers and in the case of hafnium, exceeds that achieved with thermal ionization mass spectrometers.