Frański Rafał, Gierczyk Błażej, Kozik Tomasz, Popenda Łukasz, Beszterda Monika
Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89B, 61-614, Poznań, Poland.
NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614, Poznań, Poland.
Rapid Commun Mass Spectrom. 2019 Jan 15;33(1):125-132. doi: 10.1002/rcm.8316.
The main feature of the fragmentation of [M - H] ions of methoxylated flavonoids is the loss of methyl radical (formation of the [M - H - CH ] product ion). Subsequent decomposition of [M - H - CH ] product ions may be useful for identification of a given compound by HPLC/MS. This paper describes how the selected diagnostic fragment ions can be useful during HPLC/MS(-) analysis of methoxylated flavonoids.
Product ion spectra (ESI-CID-MS/MS spectra) of [M - H] ions of 17 methoxylated flavonoids (flavones, isoflavones and flavonols) were obtained with a Q-TOF mass spectrometer. Full scan mass spectra (ESI-MS) were obtained with a single quadrupole type of instrument.
A number of product ions were recognized as useful from the point of view of structural elucidation. In most cases they were diagnostic product ions, formed as a result of C ring breaking.
The most important conclusions drawn from this study are: the product ion at m/z 132 indicates that the analysed compound is an isoflavone; the product ion at m/z 117 indicates the presence of one hydroxy group at ring B or at the 3-position; biochanin A and prunetin can be differentiated by their 'in-source' fragmentation, by the relative abundances of product ions at m/z 195, 183 and 167; loss of mass 102 from the [M - H - CH ] ion indicates that ring B is not substituted and there is no hydroxy group at the 3-position; and rhamnetin can be detected using three diagnostic product ions, namely at m/z 121, 165 and 193.
甲氧基黄酮类化合物[M-H]离子碎裂的主要特征是甲基自由基的丢失（形成[M-H-CH₃]产物离子）。[M-H-CH₃]产物离子的后续分解对于通过HPLC/MS鉴定特定化合物可能有用。本文描述了在甲氧基黄酮类化合物的HPLC/MS(-)分析过程中，选定的诊断性碎片离子如何发挥作用。
使用Q-TOF质谱仪获得了17种甲氧基黄酮类化合物（黄酮、异黄酮和黄酮醇）[M-H]离子的产物离子谱（ESI-CID-MS/MS谱）。使用单四极杆型仪器获得全扫描质谱（ESI-MS）。
从结构解析的角度来看，许多产物离子被认为是有用的。在大多数情况下，它们是由于C环断裂而形成的诊断性产物离子。
本研究得出的最重要结论是：m/z 132处的产物离子表明分析的化合物是异黄酮；m/z 117处的产物离子表明B环或3位存在一个羟基；生物chanin A和prunetin可以通过它们的“源内”碎裂，即m/z 195、183和167处产物离子的相对丰度来区分；[M-H-CH₃]离子质量损失102表明B环未被取代且3位没有羟基；可以使用三个诊断性产物离子，即m/z 121、165和193来检测鼠李素。
