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

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

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。

Three different condensed tannins were analyzed using matrix assisted lair desertion ionizationtime 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 .traits 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. Mcamwihile, the polymer with the highest intensity ion peak changed with different ion adducts.