Isotopic analysis of enriched boron by chemical ionization mass spectroscopy

A rapid and accurate CI-MS method has been developed for the isotopic analysis of enriched boron. This method involves the formation of volatile methyl borate from boric acid with direct introduction of the methyl borate into the source of a quadrupole mass spectrometer. Data acquisition and storage is computer-controlled. A subsequent BASIC computer program reads the data from the disc file, computes the average 11B/10B ratio for up to 250 separate spectra per analysis and calculates the weight percent boron-10 from the corrected 11B/10B ratio using a calibration factor based on a National Bureau of Standards boric acid standard. The relative standard deviation for the analysis of replicate samples of enriched boron with a boron-10 content in the 90 to 95% range does not exceed 0.005%. Analytical results on NBS certified enriched boron agreed to within 0.06% absolute