Alleviation of polyatomic ion interferences for determination of chlorine isotope ratios by inductively coupled plasma mass spectrometry

Abstract

A simple variation in sample preparation and introduction allows the measurement of chlorine isotope ratios by inductively coupled plasma mass spectrometry (ICP/MS). Dissolution of the sample in D 2O rather than H 2O attenuates the major polyatomic ion 36ArH + and frees m/z 37 for determination of 37Cl +. The isotope ratio 35Cl/ 37Cl in a 50 mg/L solution of Cl as LiCl is determined with a relative standard deviation of 0.21%. Sample memory is low, as the 35Cl signal decays to less than 1% of its original value after ≈2 min of cleanout with D 2O. The detection limit for Cl using this procedure is approximately 20 μg/L.