Isotopic Analysis of Highly Enriched Crystalline 28Si and Initial 28SiF4 by High-Resolution Inductively Coupled Plasma Mass Spectrometry

A procedure is described for determining the isotopic composition of highly enriched silicon as elementary 28Si and initial 28SiF4 by a single collector double focusing sector field ICP MS over a wide range of isotope concentrations (more than 6 orders of magnitude). To expand the range of measured isotopic concentrations, the signals of the main and “impurity” isotopes were recorded in solutions of different concentrations. The determination of the matrix effects and mass discrimination factors was carried out using the isotopic dilution method. This procedure allowed us to reach the uncertainty of measuring the concentration of the main isotope of ten thousandths of a percent in enriching >99.999% on a high-resolution single-collector inductively coupled plasma mass spectrometer.