多接收等离子质谱高精度测定现代人齿中Mg同位素

Separation and Isotopic Measurement of Mg Isotope Ratios in Tooth Samples Using Multiple Collector-Inductively Coupled Plasma-Mass Spectrometry

Mg是构成牙齿重要组分,其含量和同位素组成可记录居民生活地域、饮食习惯以及口腔健康信息等重要信息。本研究建立了高精度多接收等离子质谱(MC-ICP-MS)测定牙齿中Mg同位素方法。牙齿样品经微波消解仪消解,后采用AG50W-X8阳离子树脂分离溶液中的Mg元素,以1 mol/L HNO_3为介质上柱,40 m L1 mol/L HNO_3洗脱Na^+等杂质离子,再以30 m L 1 mol/L HNO_3收集Mg元素,60 m L 1 mol/L HNO_3洗去其它杂质,蒸干Mg收集液。MC-ICP-MS进行Mg同位素组成测定。MC-ICP-MS仪器自身的质量分馏利用"样品-标准"交叉技术("Sample-standard"bracketing technique)解决。实验结果表明,利用AG50W-X8阳离子树脂,可在保证Mg回收率的情况下,将牙齿样品中的Mg和其它基质元素彻底分离,且不造成同位素分馏。采用此方法对现代人离体牙牙釉质中Mg同位素进行分离测定,牙齿的δ^(26)Mg在较大的范围变化(!1.38‰~4.59‰)。本方法为利用人牙齿中Mg同位素研究Mg的暴露水平、环境污染等信息提供重要的实验和理论依据。

Major cation Mg2＋ was presented in enamel as major substituted species. The quantity of Mg and the Mg isotopic ratio in tooth can provide information on the environment, dietary habits, and oral health of individuals. As a result, a method was developed for the determination of Mg isotope based on high-precision multiple collector-inductively coupled plasma-mass spectrometry （MC-ICP-MS）. The samples were dissolved using a microwave digestion system. Separation of Mg was achieved by cation exchange chromatography of AGSOW-X8. The sample solutions were loaded on the resin with 1 mol/L HNO3 , the other ions such as Na＋ were eluted with 40 mL of HNO3（1 tool/L）, and then the Mg was eluted with 30 mL of HNO3（ 1 tool/L）, finally the resin was washed with 60 mL of HNO3 （ 1 mol/L）. The Mg isotope was measured using multiple collector-inductively coupled plasma-mass spectrometry （MC-ICP-MS）. The ＂ sample-standard＂ bracketing technique was used to correct the instrumental mass bias. The results show that the fast and effective method can be used for the separation, pre-coneentration and determination of Mg isotope in calcium-rich tooth samples. Giving values of 26Mg were from -1. 38%v to 4. 59%o. The established method for Mg isotope determination provides an important scientific basis for ancient population migration, ancient diet analysis and disease by Mg isotope of ancient human teeth.