3-氨基苯甲酸乙酯的电喷雾正离子质谱裂解规律

The cleavage pathways of 3-aminobenzoic acid ethyl ester by positive electrospray ionization mass spectrometry

目的采用电喷雾电离串联质谱(ESI-MS/MS),对3-氨基苯甲酸乙酯在正离子模式下的裂解途径进行分析研究。方法通过ESI电离产生准分子离子[M+H]+,并对[M+H]+进行碰撞诱导解离(CID)获得3-氨基苯甲酸乙酯的二级质谱图。结果在CID模式下,3-氨基苯甲酸乙酯主要产生m/z 138、m/z 94和m/z 77三个碎片离子。通过解析3-氨基苯甲酸乙酯二级质谱图得到其裂解途径信息:3-氨基苯甲酸乙酯首先断裂苯环C1位支链上的乙氧基丢失一个乙烯生成特征碎片离子m/z 138,然后断裂苯环C1位支链上酯基丢失一个CO2生成特征碎片离子m/z 94,继续断裂C3位上C-N键丢失一个NH3并生成特征碎片离子m/z 77。结论 本研究所提出的3-氨基苯甲酸乙酯的电喷雾质谱裂解规律,为其在水产品体内代谢物质的鉴别提供参考依据。

ObjectiveTo study the cleavage pathways of 3-aminobenzoic acid ethyl ester by electrospray ionization mass spectrometry (ESI-MS/MS) in the positive mode.Methods The quasi-molecular ion [M+H]+of 3-aminobenzoic acid ethyl ester was obtained by ESI, and the MS2 spectrum of quasi-molecular ion [M+H]+ ion were obtained from collision-induced dissociation (CID).Results There were three main fragment ions of quasi-molecular ion [M+H]+with CID that werem/z 138,m/z 94,m/z 77. The cleavage pathways information of [M+H]+ ion were obtained by analyzing the MS2 spectrum of [M+H]+ ion. It was found that quasi-molecular ion [M+H]+ mainly fractured through ethoxyl group at the C1 of benzene ring, and lost CH2=CH2 with gener-ated fragment ion m/z 138. A part of fragment ionm/z 138 continuously lost CO2 at the C1 of benzene ring with generated fragment ion m/z 94. Then a part of fragment ionm/z 94 lost NH3 at the C3 of benzene ring with generated characteristic fragment ion m/z 77.ConclusionThese cleavage rules presented here can provide a technical support for metabolites’ identification of 3-aminobenzoic acid ethyl ester in aquatic products.