卟啉化合物碳同位素的气相色谱同位素比值质谱测定技术

The Determination of Porphyrin Carbon Isotope Composition by Gas Chromatography-Isotope Ratio Monitoring Mass Spectrometry Technique

对于卟啉碳同位素的测定 ,传统方法 (用HPLC分离出单个卟啉化合物 ,然后燃烧成CO2 进行碳同位素的测定 )需要的样品量大 (几mg)、耗时长 ,限制了其在化学、地球科学中的应用。该文作者建立的方法是通过对卟啉化合物进行衍生化反应 ,以增强卟啉的挥发性 ,使其适用于气相色谱 同位素比值质谱 (GC IRMS)技术。对衍生化反应的整个过程进行了同位素测定 ,证实最终的衍生化硅卟啉与初始的自由基卟啉化合物碳同位素的差值在分析误差范围之内 ,无明显的同位素分馏。混合卟啉标样同位素的对比研究显示 ,在整个衍生化过程中各单体卟啉间无同位素交换分馏现象 ,可应用于卟啉碳同位素的分析。该技术的优点在于需要的样品量小 (几 μg)、时间短 ,平均偏差小。

The porphyrin carbon isotope composition can be used to explore the precursor of porphyrin,oil oil and oil source rock correction and calculation of paleo P CO 2 . The conventional method is limited because of its time consuming and large sample size(several mg of individual porphyrin) required. Therefore,it hampers the application of porphyrin carbon isotope composition into the chemistry and geoscience. The present paper describes a quantification method to prepare bis (tert butyldimethylsiloxy) silicon (Ⅳ) [(TBDMSO)\-2Si(Ⅳ)] porphyrin which is sufficiently volatile at 300 ℃ and can be used for GC IRMS analysis. The analysis of carbon isotope composition of aetio Ⅰ as the form of free base, nickel, demetalization derivative, silicon(Ⅳ) and (TBDMSO)\-2Si(Ⅳ) have shown that aetio Ⅰ porphyrin has no obvious isotope fractionation in the whole synthesis procedure for (TBDMSO)\-2Si(Ⅳ) porphyrin. The carbon isotope study on the porphyrin mixtures of aetio Ⅰ and OEP indicates that isotope exchange between porphyrins during the synthesis of (TBDMSO)\-2Si(Ⅳ) porphyrin is absent. The method can be applied to the determination of porphyrin carbon isotope compositions. The advantages of the method are time saving, less sample size and lower standard deviation.