High-precision position-specific isotope analysis
High-precision position-specific isotope analysis
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DOI：
10.1073/pnas.94.4.1049
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发表时间：
1997-02-18
影响因子：
11.1
通讯作者：
Brenna, JT
中科院分区：
文献类型：
--
作者：
Corso, TN;Brenna, JT
分子内碳同位素分布反映了有机化合物起源的细节，并可能记录复杂系统的状态，如环境或生理状态。本文报道了一种从复杂混合物中分离出的有机化合物中特定位置C-13/C-12比值的高精度测定方法。用同位素比质谱和SD的产率精度分析了分子两端的两个键断裂峰（δ-C-13）< 0.4份/千。在羧基，末端和甲基位置的同位素标记表明在活化和片段化过程中没有重排。通过改变热解温度来调节裂解程度，同位素分馏可忽略不计。总δ-C-13 = 4.06份/千份的[1-C-13]棕榈酸甲酯的羧基位置的值为+457份/千份，与稀释的预期一致，其余分子的平均值为-27.95份/千份，对应于烯烃系列的-27.46份/千份。这些数据证明了对复杂混合物中所含分子的碳进行自动化高精度位置特异性分析的可行性。
Intramolecular carbon isotope distributions reflect details of the origin of organic compounds and may record the status of complex systems, such as environmental or physiological states. A strategy is reported here for high-precision determination of C-13/C-12 ratios at specific positions in organic compounds separated from complex mixtures, Free radical fragmentation of methyl palmitate, a test compound, is induced by an open tube furnace, Two series of peaks corresponding to bond breaking from each end of the molecule are analyzed by isotope ratio mass spectrometry and yield precisions of SD(delta-C-13) < 0.4 parts per thousand. Isotope labeling in the carboxyl, terminal, and methyl positions demonstrates the absence of rearrangement during activation and fragmentation. Negligible Isotopic fractionation was observed as degree of fragmentation was adjusted by changing pyrolysis temperature. [1-C-13]methyl palmitate with overall delta-C-13 = 4.06 parts per thousand, yielded values of +457 parts per thousand for the carboxyl position, in agreement with expectations from the dilution, and an average of -27.95 parts per thousand for the rest of the molecule, corresponding to -27.46 parts per thousand for the olefin series. These data demonstrate the feasibility of automated high-precision position-specific analysis of carbon for molecules contained in complex mixtures.