基质辅助激光解吸附飞行时间质谱分析缩合单宁的阳离子化问题

以单价金属离子Cs 和Na 作为离子化试剂,对3种缩合单宁进行基质辅助激光解吸附飞行时间(MALD I-TOF)质谱分析。加入Na 作为阳离子化试剂,能得到较高质量的质谱图。但由于实验通道中几乎不可能完全去除的K 的干扰而会高估棓儿茶酚/表棓儿茶酚单元的组成比例,从而影响对棓儿茶酚/表棓儿茶酚单元存在与否的判断;选择Cs 作为阳离子化试剂可以避免此问题,但在复杂的缩合单宁分析中,同样因为杂质离子Na 和K 的干扰而使得质谱图变得更复杂;未去离子处理直接对缩合单宁进行MALD I-TOF质谱分析与去离子并加入Cs 的处理比去离子并加入Na 能检测到更高聚合度的高聚物,检测到离子峰强度最高的聚合物随离子不同而不同。

Prerequisite Knowledge of the Effects of Adduct Ions on Matrix-assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry of Condensed Tannins

Three different condensed tannins were analyzed using matrix assisted laser desorption ionization-time of flight mass spectrometry(MALDI-TOFMS) by selection of Cs~( ) and Na~( ) as the cationization reagents.When Na~( ) was employed as the cationization reagent,condensed tannins gave the quality MALDI-TOF(spectra),accompanying with the possibility of overevaluation of the gallocatechin/epigallocatechin units because of the influence of remaining K~( ).It is critical to investigate the appearance of gallocatechin/epigallocatechin units in condensed tannins from specially plant tissues.Cs~( ) is a suitable substitute for this situation.The more complicated MALDI-TOF spectrum of the complex condensed tannins from Bruguiera gymnorrhiza leaves was detected by selection of Cs~( ) as the cationization reagent with the presence of Na~( ) and K~( ).Using MALDI-TOF with no deionization or deionization and selection of Cs~( ) as the cationization reagent rather than with denionization and selection of Na~( ),the condensed tannin polymers of higher polymerization degree(PD) was oberved.Meanwhile,the polymer with the highest intensity ion peak changed with different ion adducts.