1)Thermo Electron (Bremen) GmbH, Barkhausenstr. 2, 28197, Germany, 2) Institut für Geologie Mineralogie und Geohphysik, Ruhr Universität Bochum, Universitätsstr. 150, 44801, Germany, 3) University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada Journal of Analytical Atomic Spectrometry (2004), V19, pp844-851, doi: 10.1039/b403339f High precision calcium isotope ratio measurements using a magnetic sector multiple collector inductively coupled plasma mass spectrometer Michael E. Wieser (1,3), Dieter Buhl (2), Claudia Bouman (1) and Johannes Schwieters (1) Calcium isotope abundances were measured using a Finnigan Neptune magnetic sector multiple collector inductively coupled plasma mass spectrometer capable of resolving all molecular isobaric interferences from 42Ca, 43Ca, 44Ca, 46Ca and 48Ca. Scattering events caused by the intense 40Ar+ ion beam did not contribute to the uncertainty in the baseline of the calcium mass spectrum. Quantitative separation of the calcium from the sample matrix was carried out to ensure that the measurements were independent of the sample type. In addition, thorough desolvation of the aerosol was found to have a significant effect on the stability and sensitivity of the method.