Measurement of calcium isotopes (δ44Ca) using a multicollector TIMS technique

We propose a new multicollector technique for the thermal ionization mass spectrometer (TIMS) measurement of calcium (Ca) isotope ratios improving average internal statistical uncertainty of the Ca-44/Ca-40 measurements by a factor of 2-4 and average sample throughput relative to the commonly used peak jumping method by a factor of 3. Isobaric interferences with potassium (K-40(+)) and titanium (Ti-48(+)) or positively charged molecules like (MgF+)-Mg-24-F-19, (MgF+)-Mg-25-F-19, (MgO+)-Mg-24-O-16 and (AlO+)-Al-27-O-16 can either be corrected or are negligible. Similar, peak shape defects introduced by the large dispersion of the whole Ca isotope mass range from 40-48 atomic mass units (amu) do not influence Ca-isotope ratios. We use a Ca-43/Ca-48 double spike with an iterative double spike correction algorithm for precise isotope measurements. (Int J Mass Spectrom 220 (2002) 385-397) (C) 2002 Elsevier Science B.V. All rights reserved.