Boron isotope analysis. A review

Over the last ten years there has been a rapid increase in the number of studies of the boron isotope composition of natural samples. These studies have employed a variety of methods, with varying degrees of accuracy and precision. The relevant techniques are discussed in this paper and the problems associated with the measurement of boron isotope are divided into those dealing with (i) the extraction of boron from different types of samples (ii) purification of the extracted boron and (iii) mass spectrometric analysis of boron isotopes. The advantages and disadvantages of the different techniques are discussed. In addition, some refinements of these published methods and a new purification stage are presented. No one single method is appropriate for all studies; instead the choice of analytical method depends on the type of sample under consideration, the level of precision required to solve the problem, and the analytical equipment that is available. There is, however, a general requirement for more consideration to be given to assessing the reproducibility of some techniques and there is also a need for the development of working standards appropriate to the different types of natural samples, and the natural range of boron isotope ratios in these different types of samples.