title: 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.
abstract: 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 (133)Cs2(11)B(16)O2(+)(m/z 309) and (133)Cs2(10)B(16)O2(+) (m/z 308) ions in adjacent H3-H4 Faraday cups with typical zoom optics parameters (Focus Quad: 15 V, Dispersion Quad: -85 V). The external reproducibilities of the measured (11)B/(10)B ratios of the NIST 951 boron standard solutions of 1000 ng, 100 ng and 10 ng 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 δ(11)B values with a mean of 39.66±0.35‰ for seawater in the whole range of boron content from 5 ppb to 200 ppb, 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 δ(11)B values ranging from -25‰ to +40‰.
authors.affiliation: State Key Laboratory for Mineral Deposits Research, Department of Earth Sciences, Nanjing University, Nanjing 210093, PR China.
authors.forename: Hai-Zhen
authors.initials: HZ
authors.lastname: Wei
authors.affiliation: State Key Laboratory for Mineral Deposits Research, Department of Earth Sciences, Nanjing University, Nanjing 210093, PR China; State Key Laboratory of Geological Processes and Mineral Resources, Faculty of Earth Resources, China University of Geosciences, Wuhan, Hubei 430074, PR China. Electronic address: shyjiang@nju.edu.cn.
authors.forename: Shao-Yong
authors.initials: SY
authors.lastname: Jiang
authors.affiliation: Department of Earth and Environmental Sciences, Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964-8000, USA; Queens College School of Earth and Environmental Sciences, Flushing, NY 11367, USA.
authors.forename: N Gary
authors.initials: NG
authors.lastname: Hemming
authors.affiliation: State Key Laboratory for Mineral Deposits Research, Department of Earth Sciences, Nanjing University, Nanjing 210093, PR China.
authors.forename: Jing-Hong
authors.initials: JH
authors.lastname: Yang
authors.affiliation: State Key Laboratory for Mineral Deposits Research, Department of Earth Sciences, Nanjing University, Nanjing 210093, PR China.
authors.forename: Tao
authors.initials: T
authors.lastname: Yang
authors.affiliation: State Key Laboratory for Mineral Deposits Research, Department of Earth Sciences, Nanjing University, Nanjing 210093, PR China.
authors.forename: He-Pin
authors.initials: HP
authors.lastname: Wu
authors.affiliation: State Key Laboratory for Mineral Deposits Research, Department of Earth Sciences, Nanjing University, Nanjing 210093, PR China.
authors.forename: Tang-Li
authors.initials: TL
authors.lastname: Yang
authors.affiliation: State Key Laboratory for Mineral Deposits Research, Department of Earth Sciences, Nanjing University, Nanjing 210093, PR China.
authors.forename: Xiong
authors.initials: X
authors.lastname: Yan
authors.affiliation: State Key Laboratory for Mineral Deposits Research, Department of Earth Sciences, Nanjing University, Nanjing 210093, PR China.
authors.forename: Wei
authors.initials: W
authors.lastname: Pu
keywords: Boron isotopes; Multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS); Positive thermal ionization mass spectrometry (PTIMS); Separation/purification procedure