Justesen U
Institute of Food Research and Nutrition, Division of Nutrition, Danish Veterinary and Food Administration, Mørkhøj Bygade 19, DK-2860 Søborg, Denmark.
J Mass Spectrom. 2001 Feb;36(2):169-78. doi: 10.1002/jms.118.
Electrospray operated in the negative mode was used to analyse methoxylated flavonoids. They were found to produce radical anions by collision-induced fragmentation of the aglycones. Loss of a methyl group from the deprotonated molecule corresponding to [M - H - 15]-* ions, as well as [M - H - 15-28]-* and [M - H - 15-29]- fragment ions, were found to constitute the characteristic fragmentation for the monomethoxylated species, whereas [M - H - 15]-*, [M - H - 30]- and [M - H - 30-28]- were predominant for the polymethoxylated species. Obtained under similar conditions, the product-ion spectra of isomeric compounds were characteristically different. It is therefore possible to distinguish between methoxylated flavonoids with identical molecular mass, e.g. when screening plant extracts for flavonoid composition. However, comparison with standard compounds is necessary for the identification of unknown flavonoid aglycones.
采用负模式运行的电喷雾来分析甲氧基黄酮类化合物。发现它们通过苷元的碰撞诱导裂解产生自由基阴离子。去质子化分子失去一个甲基对应于[M - H - 15]-*离子，以及[M - H - 15 - 28]-和[M - H - 15 - 29]-碎片离子，被发现构成单甲氧基化物种的特征性裂解，而[M - H - 15]-、[M - H - 30]-和[M - H - 30 - 28]-对于多甲氧基化物种占主导。在相似条件下获得的异构体化合物的产物离子谱具有特征性差异。因此，有可能区分分子量相同的甲氧基黄酮类化合物，例如在筛选植物提取物中的黄酮类化合物组成时。然而，对于鉴定未知黄酮类苷元，与标准化合物进行比较是必要的。
