Comparison of microsublimation and ion exchange chromatography for boron isolation preceding its isotopic analysis via multi-collector ICP-MS

© 2014 the Partner Organisations. Boron isotopic analysis is of interest in many research fields and for a large variety of sample types. Accurate and precise determination of boron isotope ratios using multi-collector ICP-mass spectrometry or thermal ionization mass spectrometry requires isolation of the target element prior to isotopic analysis, which is accomplished using either ion exchange chromatography or microsublimation. This study systematically compares the two methods in terms of B recovery, procedural blank, matrix removal efficiency, accuracy and precision of the resulting δ11B values as measured using multi-collector ICP-mass spectrometry, as well as labor intensiveness and costs. For this purpose, four types of sample matrices, i.e. 20 g L-1Ca aqueous solution, seawater, digests of spinach (100 g L-1) and silicate glass (10 g L-1), were stripped from their original B content and spiked with B of known isotopic composition and were then subjected to both sample preparation methods and subsequent isotopic analysis of the purified B fraction via multi-collector ICP-mass spectrometry. For both methods, the highest (quantitative) B recoveries were obtained for Ca-rich aqueous solution and seawater. For spinach, accurate δ11B values were obtained after ion exchange chromatography. However, microsublimation was plagued by isotope fractionation, resulting in large offsets (∼8‰) between the experimental results and the corresponding reference values. For glass, B recovery was incomplete, nevertheless the absence of fractionation rendered both sample preparation methods suitable. Overall, in the absence of isotope fractionation, microsublimation appears advantageous in terms of procedural blanks, matrix removal efficiency, precision (2 s) on δ11B values, labor intensiveness and costs.crosscheck: This document is CrossCheck deposited related_data: Supplementary Information copyright_licence: The Royal Society of Chemistry has an exclusive publication licence for this journal copyright_licence: The accepted version of this article will be made freely available in the Chemical Sciences Article Repository after a 12 month embargo period history: Received 31 March 2014; Accepted 9 July 2014; Accepted Manuscript published 9 July 2014; Advance Article published 1 August 2014; Version of Record published 10 September 2014status: publishe