生油岩中地卟啉的质谱分析显示主要由两类卟啉组成 (DPEP和ETIO) ,多数卟啉化合物碳数超过C3 2 ;分子离子 (C3 4～ 3 6DPEPs)的子离子谱显示有甲基和乙基的丢失 ,表明其分子离子中存在乙基和丙基 .根据串联质谱信息所获取的平均分子结构简式明确表征了卟啉吡咯环外取代基的组成 ,其取代基组成规律性的变化 ,揭示了地卟啉在地质体中的脱烷基演化作用 Mass spectrometry analysis of porphyrin in the source rock shows that it mainly consists of two types of porphyrins (DPEP and ETIO) and the majority of the porphyrin compounds exceed C3 2; the ion spectrum of the molecular ions (C3 4 ~ 3 6 DPEPs) The loss of ethyl group and ethyl group showed that there existed ethyl and propyl groups in their molecular ions.According to the average molecular structure obtained by tandem MS information, the composition of substituents outside the pyrrole ring of porphyrin was clearly characterized, The changes of depo-alkyl groups in geologic bodies were revealed