ESI-IT-TOF-MS~n方法对11个异黄酮的裂解规律研究

本文对选定的11个异黄酮化合物在ESI-IT-TOF-MS n的裂解规律进行研究。文章采用ESI-IT-TOF-MS n仪对样品进行高分辨质谱测定,正负离子多级切换,通过对质谱碎片离子进行预测,并根据结构对其质谱可能的裂解规律进行总结研究。由于在正离子模式下信号较强,采用正离子模式对11个异黄酮多级碎片离子分析,发现异黄酮苷的裂解主是优先断裂糖苷键？C环4位羰基易于中性丢失CO（–28）,而C环经过RDA裂解形成的A^1,3＋则能够比较A环与B环上的羟基取代位置？A环上有相邻羟基存在时,也易中性丢失CO（–28）或H2O（–18）？B环有甲氧基取代时中性丢失CH4（–16）、自由基（CH3）或CH3OH（–32）为常见,但A环与B环有单独羟基时也偶见中性丢失CO（–28）。通过ESI-IT-TOF-MS n方法,选定多级正离子模式下对异黄酮的裂解进行了总结,有利于了解异黄酮在质谱中的裂解行为,对于异黄酮类化合物相关的结构推测有重要意义。

Investigations of the fragmentation behavior of 11 isoflavones with ESI-IT-TOF-MSn

The fragmentation behavior of isoflavones was studied using electrospray ionization-ion trap-time of flight mass spectrometry （ESI-IT-TOF-MSn）. It was found that the isoflavone glycoside bond was easily broken. The fragmentation occurred mostly on the C-ring, and the fragment ions of A^1,3＋ produced by the RDA cracking will predict the hydroxylation replacement on A-ring or B-ring. In addition, four carbonyl groups on the C-ring were fragmented through neutral loss of 28 （-CO）. A and B-rings primarily lose substituents which including a neutral losses of 32 （-CH3OH）, 16 （-CH4）, or 16 （-O）, and 18 （-H2O）. A-ring in the presence of adjacent hydroxylation, also easily made to be a neutral losses of 28 （-CO） or 18 （-H20）. It is likewise common to see methoxy replaced with a neutral losses of 16 （-CH4） or 32 （-CHaOH） in B-ring, also the hydroxylation on benzene ring can occasionally results with the neutral loss of 28 （-CO）.