High precision measurement of titanium isotope ratios by plasma source mass spectrometry

A method using multiple-collector inductively coupled plasma source mass spectrometry for the precise measurement of Ti isotope composition in natural materials has been developed. Instrumental mass discrimination is corrected using a standard-sample bracketing approach by expressing the isotope ratios of samples relative to those of the bracketing standard. Variations in(47)Ti/Ti-46, Ti-48/Ti-46, Ti-49/Ti-46 and Ti-50/Ti-46 ratios of samples are expressed in epsilon units which are deviations in parts per 10(4) from the same isotope ratios of the reference material. The long-term repeatability at the 2 standard deviation level is 0.4, 0,6,0.7 and 0.8 epsilon units in terms of Ti-47/Ti-46, Ti-48/Ti-46, Ti-49/Ti-46 and Ti-50/Ti-46 ratio measurements, respectively. The technique reported here makes it possible for the first time that both mass-dependent fractionation and isotope anomalies of Ti isotopes in natural materials can be measured to high precision. (C) 2002 Elsevier Science B.V. All rights reserved.