元素分析仪-稳定同位素比值质谱仪测定胶乳总固形物碳含量及其稳定碳同位素  

Determination of Carbon Content in Total Solids of Latex and Its Stable Carbon Isotope Ratio (δ13C) by EA and IRMS in Hyphenation

作　　者：罗雪华[1] 王文斌[1] 吴小平[1] 王大鹏[1] 张永发[1] 薛欣欣[1] 赵春梅[1] LUO Xuehua;WANG Wenbin;WU Xiaoping;WANG Dapeng;ZHANG Yongfa;XUE Xingxin;ZHAO Chunmei(Rubber Research Institute,Chinese Academy of Tropical Agricultural Sciences,Haikou 571101,China)

机构地区：[1]中国热带农业科学院橡胶研究所

出　　处：《理化检验（化学分册）》2019年第12期1365-1372,共8页Physical Testing and Chemical Analysis(Part B:Chemical Analysis)

基　　金：中国热带农业科学院基本科研业务费专项(1630022017006)

摘　　要：应用元素分析仪和稳定同位素比值质谱仪(EA-IRMS)联用技术测定了胶乳总固形物碳含量及其碳同位素比值δ13C。将所采集的新鲜胶乳预先制成胶片,称取(0.500±0.100)mg样品,按EA仪器工作条件对其碳含量进行测定。分别用碳元素基准物质(尿素、天门冬氨酸、葡萄糖、蔗糖),在EA工作条件下测其碳元素,以碳质量为横坐标,CO2峰面积为纵坐标制得标准曲线,结果表明其线性关系良好。对EA-IRMS系统作了稳定性和线性试验,前者达到小于0.1‰的要求,后者则满足同类仪器小于0.06‰·V-1的要求。此外,还对Craig校正所得样品及3种CRMs的初始校正值作进一步校准的3种校准方法作了比较,结果表明:3种方法中回归法准确度最好,适用于不同性质、不同碳同位素组成的样品;而截距法只能用于碳同位素组成与参考气相近的样品的测量数据的校准;原始回归法则不能有效地消除测定过程中17O的影响和样品燃烧过程中可能存在的同位素分馏的影响而不能用于结果校准。测得胶乳样品的总固形物碳质量分数为81.83%,δ13Cs-PDBM(PDB为国际标准拟箭石化石)为-26.70‰(回归法校准值)。Hyphenation of EA and IRMS was applied to the determination of carbon content and carbon isotope ratio(δ13 C)in total solids of latex sample.A portion(0.500±0.100)mg of the dried and transparent latex piece,prepared from fresh latex was analyzed for its carbon content by EA under its working condition.Primary carbon standards of urea,aspartic acid,glucose and sucrose were used separately to prepare standard curves of carbon and good linearities were obtained between values of mass concentration of carbon and their respective peak areas of CO2.Stability and linearity of the EA-IRMS system were tested,giving stability index less than 0.1‰,and linearity index less than 0.06‰·V-1,both of which met with the qualifications quite well.A comparison study on 3 calibration methods used to calibrate the initial corrected values of the latex sample and 3 CRMs obtained by Craig correction method was also made.It was shown that:accuracy of the regression method was found to be best among the 3 methods,it could be used for calibration of initial corrected values of samples with different properties or with different compositions of carbon isotopes;the interception method could be used only for calibration of data of samples with their compositions of carbon isotopes close to that of the reference gas;and interferences due to 17O and fractional distillation of isotopes could not be eliminated by the original regression method,hence it could not be used for calibration of the determined data.It was found by the proposed method that the carbon content of in total solids of latex sample was 81.83%and value ofδ13 CMs-PDBfound was-26.70‰(calibrated value by the regression method).

关 键 词：元素分析仪-同位素比值质谱仪联用系统 胶乳总固形物碳含量 稳定碳同位素比值 校准方法 

分 类 号：O657.63[理学—分析化学] O613.71[理学—化学]