氨基甲酸酯类化合物电喷雾多级质谱分析中一种特殊的中性丢失CO_2的重排反应

采用电喷雾电离 -离子阱质谱和电喷雾电离 -傅立叶变换离子回旋共振质谱技术 ,对 2种具有氨基甲酸酯结构的化合物进行碰撞诱导解离研究。注射泵直接进样 ,正离子方式检测。在其二级质谱图中主要产生M+H-44 ]+ 的碎片离子 ,通过对碎片离子进行精确质量测定 ,证实为化合物的氨基甲酸酯部分脱去一分子CO2 而形成 ,这一现象同样出现在另外 5种具有氨基甲酸酯结构化合物的碰撞诱导解离分析中。推测这一包含两个化学键断裂的中性丢失可能经历特殊的分子内重排过程 ,并对其重排裂解机理进行了初步探讨。

An Unusual Rearrangement Process of Neutral Loss of CO2 in Carbamates by Electrospray Ionization-Multistage Mass Spectrometry

To investigate the fragmentation behaviors of two compounds containing carbamate group by collision induced dissociation(CID). Both electrospray ionzation-ion trap mass spectrometry and electrospray ionization-Fourier transform ion cyclotron resonance mass spectrometry were used to analyze the compounds. The samples were infused into the ion source with a syringe pump and the experiments were carried out in the positive ion mode. The most abundant fragment ion in MS2 spectrum was M+H-44]+ ion. The accurate masses of the fragment ions suggested that the loss of 44u corresponded to the loss of CO 2. The same phenomenon was also observed in the CID analysis of other five compounds containing carbamate group. The neutral loss involving the cleavage of two bonds suggested an unusual rearrangement process. A mechanism for the loss of CO 2 has been proposed.