官能团对染料在电喷雾串联质谱中的离子化和裂解行为的影响

采用电喷雾串联质谱（ESI-MS/MS）直接进样法研究了直接红28、碱性红9、分散蓝1和分散黄1等4种有害的纺织品染料的质谱行为规律，探讨了染料的电喷雾电离和碰撞诱导裂解（CID）的机理。实验发现，强极性染料直接红28和碱性红9的电喷雾电离与其分子结构内的强极性基团有关，弱极性染料分散蓝1和分散黄1的电喷雾电离与其分子结构内的电负性基团有关，染料电喷雾特征离子都为最外层带有偶数电子的偶电子离子；偶氮、三苯甲烷、蒽醌和硝基苯等发色团在染料的二级质谱中都发生了裂解，偶电子离子在CID模式下除了发生中性丢失，还会裂解生成1个奇电子离子和1个奇电子自由基；偶电子离子和奇电子离子的质量数都满足其相应的氮规则。

Effects of Functional Groups on Ionization and Fragmentation of Dyestuffs by ESI-MS/MS

Mass behavior of electrospray ionization and fragmentation mechanism of 4 harmful textile dyestuffs (direct red 28, basic red 9, disperse blue 1 and disperse yellow 1) were discussed using electrospray ionization-tandem mass spectrometry(ESI-MS/MS). Experiments demonstrate that polar groups in molecule affect the ionization behavior of strong polar dyestuffs (direct red 28 and basic red 9). But for weak polar dyestuffs (disperse blue 1 and disperse yellow 1), the electron-withdrawing groups and electron-donating groups have great effects on the ionization behavior. Most characterized ions are even-electron ions (EE) due to soften ionization of ESI. The chromophore groups in the researched dyestuffs, such as azo, triphenylmethane, anthraquinone and nitrobenzene are found to cleavage in the mode of collision induced dissociation (CID). In ESI-MS/MS spectra, there are two main fragmentation pathways of a EE: one involves loss of an neutral molecule to yield another EE, and the other involves loss of an neutral radical (EE~0. ) to yield an odd-electron ion (OE.). Beside, the molecular mass (m/z) of both EE and OE. are found to follow their corresponding nitrogen rules in accordance with the nitrogen atoms contained.