A review on the determination of isotope ratios of boron with mass spectrometry

The present review discusses different mass spectrometric techniques—viz, thermal ionization mass spectrometry (TIMS), inductively coupled plasma mass spectrometry (ICPMS), and secondary ion mass spectrometry (SIMS)—used to determine ¹¹B/¹⁰B isotope ratio, and concentration of boron required for various applications in earth sciences, marine geochemistry, nuclear technology, environmental, and agriculture sciences, etc. The details of the techniques-P-TIMS, which uses Cs₂BO₂ ⁺, N-TIMS, which uses BO₂ ⁻, and MC-ICPMS, which uses B⁺ ions for bulk analysis or B⁻ and B⁺ ions for in situ micro-analysis with SIMS—are highlighted. The capabilities, advantages, limitations, and problems in each mass spectrometric technique are summarized. The results of international interlaboratory comparison experiments conducted at different times are summarized. The certified isotopic reference materials available for boron are also listed. Recent developments in laser ablation (LA) ICPMS and QQQ-ICPMS for solids analysis and MS/MS analysis, respectively, are included. The different aspects of sample preparation and analytical chemistry of boron are summarized. Finally, the future requirements of boron isotope ratios for future applications are also given. Presently, MC-ICPMS provides the best precision and accuracy (0.2–0.4‰) on isotope ratio measurements, whereas N-TIMS holds the potential to analyze smallest amount of boron, but has the issue of bias (+2‰ to 4‰) which needs further investigations.