多氯联苯的质谱裂解规律探析

The Fragmentation Patterns of Polychlorinated Biphenyls

分析比较了6种多氯联苯(PCBs)化合物在电子轰击离子源(EI)和大气压化学离子源(APCI)条件下的质谱裂解规律。在APCI离子源中,无(准)分子离子峰,但存在质量比化合物分子质量少19u的加合离子峰,此加合离子同位素峰的强度变化规律与EI质谱中分子离子同位素峰的强度变化规律一致;结合不同流动相辅助探讨此类物质的裂解途径,推断该加合离子是多氯联苯解离一个氯原子后从流动相的水分子中捕获一个羟基,随后又失去一个质子形成的。该质谱裂解规律有助于为此类化合物的快速鉴定提供依据。

Fragmentation patterns of six polychlorinated biphenyls （PCBs） under electron impact ionization（EI） and atmospheric pressure chemical ionization（APCI） mode were compared.In the negative APCI source,there were not quasi-molecular ions and only adduct ions whose masses were 19 u less than their corresponding molecular weights existed.The intensity variation trend of these adduct ions corresponds well with those of their corresponding molecular isotopic ions detected in EI-MS mode.By using different mobile phases,it was proposed that these adduct ions may be generated by losing one chloride atom,capturing one hydroxyl from water in the mobile phase,and losing one proton.The fragmentation patterns facilitates the identification of polychlorinated biphenyls.