title: Direct separation of boron from Na- and Ca-rich matrices by sublimation for stable isotope measurement by MC-ICP-MS.
abstract: An improved technique for precise and accurate determination of boron isotopic composition in Na-rich natural waters (groundwater, seawater) and marine biogenic carbonates was developed. This study used a 'micro-sublimation' technique to separate B from natural sample matrices in place of the conventional ion-exchange extraction. By adjusting analyte to appropriate pH, quantitative recovery of boron can be achieved (>98%) and the B procedural blank is limited to <8 pg. An additional mass bias effect in MC-ICP-MS was observed which could not be improved via the standard-sample-standard bracketing or the 'pseudo internal' normalization by Li. Therefore a standard other than NBS SRM 951 was used to monitor plasma condition in order to maintain analytical accuracy. An isotope cross-calibration with results from TIMS shows that the space-charge mass bias on MC-ICP-MS can be successfully corrected using off-line mathematical manipulation. Several reference materials, including the seawater IAPSO and two groundwater standards IAEA-B-2 and IAEA-B-3, were used to validate this approach. We found that the delta(11)B of the reference coral JCp-1 was 24.22+/-0.28 per thousand, corresponding to seawater pH based on the coral delta(11)B-pH function.
authors.affiliation: Department of Earth Sciences, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Bo-Shian
authors.initials: BS
authors.lastname: Wang
authors.forename: Chen-Feng
authors.initials: CF
authors.lastname: You
authors.forename: Kuo-Fang
authors.initials: KF
authors.lastname: Huang
authors.forename: Shein-Fu
authors.initials: SF
authors.lastname: Wu
authors.forename: Suresh Kumar
authors.initials: SK
authors.lastname: Aggarwal
authors.forename: Chuan-Hsiung
authors.initials: CH
authors.lastname: Chung
authors.forename: Pei-Ying
authors.initials: PY
authors.lastname: Lin