Thermal ionization mass spectrometry (TIMS) produces the most reliable results and is the method of choice for precise boron isotopic determination. This chapter reviews the thermal ionization mass spectrometry techniques for Boron isotopic analysis. Boron is a quintessential crustal element that is widely distributed in surface rocks and aqueous fluids on Earth. It has two natural stable isotopes, 10B and 11B. The application of the boron isotopes as a geochemical tracer in earth sciences is considerably increasing. According to the charge condition of ionized species inside mass spectrometer, the TIMS methods are sub-divided into two categories namely the positive-TIMS and the negative-TIMS. The Cs-borate positive-TIMS and the BO2 negative-TIMS are the most commonly used techniques today. The Cs-borate technique achieves a better precision, but with low ionization efficiency and lengthy chemical preparation. The modified BO2 negative-TIMS applying the oxygen normalization attains a similar precision level as Cs-borate, but can be applied to low abundance natural samples with simple chemistry. The new BO2 negative-TIMS technique is crucial for re-evaluation of small change of 11B or 10B in foraminferal shells and to check possible oceanic pH variations.
All Science Journal Classification (ASJC) codes
- Earth and Planetary Sciences(all)