An improved procedure for separation/purification of boron from complex matrices and high-precision measurement of boron isotopes by positive thermal ionization and multicollector inductively coupled plasma mass spectrometry

• Published in: Talanta (Oxford) 2014-06, Vol.123, p.151-160
• Main Authors: Wei, Hai-Zhen, Jiang, Shao-Yong, Gary Hemming, N., Yang, Jing-Hong, Yang, Tao, Wu, He-Pin, Yang, Tang-Li, Yan, Xiong, Pu, Wei
• Format: Article
• Language: English
• Subjects: Boron; Boron isotopes; Collection; Dispersions; Ionization; Multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS); Nanostructure; Positive thermal ionization mass spectrometry (PTIMS); Purification; Separation; Separation/purification procedure
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2014.02.009

In order to eliminate boron loss and potential isotopic fractionation during chemical pretreatment of natural samples with complex matrices, a three-column ion-exchange separation/purification procedure has been modified, which ensures more than 98% recovery of boron from each step for a wide range of sample matrices, and is applicable for boron isotope analysis by both TIMS and MC-ICP-MS. The PTIMS-Cs2BO2+-static double collection method was developed, ensuring simultaneous collection of 133Cs211B16O2+(m/z 309) and 133Cs210B16O2+ (m/z 308) ions in adjacent H3–H4 Faraday cups with typical zoom optics parameters (Focus Quad: 15 V, Dispersion Quad: −85V). The external reproducibilities of the measured 11B/10B ratios of the NIST 951 boron standard solutions of 1000ng, 100ng and 10ng of boron by PTIMS method are ±0.06‰, ±0.16‰ and ±0.25‰, respectively, which indicates excellent precision can be achieved for boron isotope measurement at nanogram level boron in natural samples. An on-peak zero blank correction procedure was employed to correct the residual boron signals effect in MC-ICP-MS, which gives consistent δ11B values with a mean of 39.66±0.35‰ for seawater in the whole range of boron content from 5ppb to 200ppb, ensuring accurate boron isotope analysis in few ppb boron. With the improved protocol, consistent results between TIMS and MC-ICP-MS data were obtained in typical geological materials within a wide span of δ11B values ranging from −25‰ to +40‰. [Display omitted] •Three-column ion-exchange procedure was modified for boron separation/purification.•The PTIMS-Cs2BO2+-static double-collection method has been established.•The dominant effects that cause deviation on measured δ11B were discussed.