Determination of boron content and isotopic composition in gypsum by inductively coupled plasma optical emission spectroscopy and positive thermal ionization mass spectrometry using phase transformation

Yun-Qi Ma; Zhang-Kuang Peng; Jian Yang; Ying-Kai Xiao; Yan-Ling Zhang

doi:10.1016/j.talanta.2017.07.006

Determination of boron content and isotopic composition in gypsum by inductively coupled plasma optical emission spectroscopy and positive thermal ionization mass spectrometry using phase transformation

Talanta. 2017 Dec 1:175:250-255. doi: 10.1016/j.talanta.2017.07.006. Epub 2017 Jul 4.

Authors

Yun-Qi Ma¹, Zhang-Kuang Peng², Jian Yang³, Ying-Kai Xiao⁴, Yan-Ling Zhang⁵

Affiliations

¹ Laboratory of Salt Lake Geology and Environment, Qinghai Institute of Salt Lakes, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Xining 810008, China; Salt Lake Chemical Analyzing and Testing Center, Qinghai Institute of Salt Lakes, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Xining 810008, China. Electronic address: yqma@isl.ac.cn.
² Laboratory of Salt Lake Geology and Environment, Qinghai Institute of Salt Lakes, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Xining 810008, China; University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: 1962976398@qq.com.
³ Laboratory of Salt Lake Geology and Environment, Qinghai Institute of Salt Lakes, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Xining 810008, China; University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: 115013218@st.cidp.edu.cn.
⁴ Laboratory of Salt Lake Geology and Environment, Qinghai Institute of Salt Lakes, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Xining 810008, China. Electronic address: Xiaoyk@isl.ac.cn.
⁵ Laboratory of Salt Lake Geology and Environment, Qinghai Institute of Salt Lakes, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Xining 810008, China. Electronic address: ylzhang@isl.ac.cn.

PMID: 28841987
DOI: 10.1016/j.talanta.2017.07.006

Abstract

As a stable isotope, boron plays an important role in hydrogeology, environmental geochemistry, ore deposit geochemistry and marine paleoclimatology. However, there is no report of boron isotopic composition in gypsum. This is mainly confined to complete dissolution of Gypsum by water or acid. In this study, gypsum was converted to calcium carbonate (CaCO₃) with ammonium bicarbonate(NH₄HCO₃) by two steps at 50°C. In every step, the mass ratio of NH₄HCO₃/CaSO₄·2H₂O was twice, and conversion rate reached more than 98%. Converted CaCO₃ was totally dissolved with hydrochloric acid (the dissolution rate was over 99%). In order to overcome the difficulties of the matrix interference and the detection limit of Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), we use Amberlite IRA 743 resin to purify and enrichment the boron at first, then eluting boron from the resin with 10mL 0.1mol/L hydrochloric acid at 75°C. The boron isotopic composition of natural gypsum samples was determined using positive thermal ionization mass spectrometry (P-TIMS). The boron isotopic composition of gypsum may be an excellent indicator for the formation environment.

Keywords: Boron isotope; Gypsum; ICP-OES; P-TIMS; Phase transformation.