Department of Pathology & Laboratory Medicine, University of British Columbia, Child & Family Research Institute, Vancouver, BC, V5Z 4H4, Canada.
Rapid Commun Mass Spectrom. 2013 Jun 30;27(12):1319-28. doi: 10.1002/rcm.6570.
Electrospray ionization tandem mass spectrometry (ESI-MS/MS) offers the unique opportunity to characterize complexes of the organophosphorus pesticide (OP) quinalphos (PA-Q) with transition metal ions immediately formed after contact. This study complements research looking at longer term kinetics of quinalphos hydrolysis in the presence of transition metal ions and gives insights into the structural features of the initial complex formation in solution. (Hydrolysis reaction: PA-Q + H2 O → PA-OH + HQ, where PA-OH is the diethyl phosphate product and HQ is hydroxyquinoxaline.)
Low micromolar PA-Q solutions with an approximately 3-fold molar excess of transition metal ions were immediately analyzed after mixing. Fragmentation of the transition metal ion complexes with PA-Q was accomplished in two different ways: first, in-source fragmentation by elevating the declustering potential and second, low-energy collision-induced dissociation (CID).
For Ag(+), the [PA-Q - Ag(+)] and respective Ag(+) -containing degradation product ions are readily observed. For Cu(2+), we observed the [PA-Q + Cu(2+) + NO3(-)] complex ion with weak intensity and strong signals from both the [2PA-Q + Cu(+)] and the [PA-Q + Cu(+)] ions, the latter two attributable to charge-state reduction in the gas phase from Cu(II) to Cu(I), indicating that PA-Q fulfills specific structural requirements of the formed complex for charge-state reduction during transition from solution to the gas phase. For Hg(2+), the [PA-Q + Hg(2+) + (PA-OH - H)(-)] ion was the largest observed species containing one Hg(2+) ion. No 1:1 species ([PA-Q] or other degradation products:Hg(2+)) was observable.
ESI-MS/MS of complexes formed from PA-Q and transition metal ions is a formidable technique to probe initial formation of these complexes in solution. Previous work from other groups established structural requirements that enable charge-state reduction from Cu(II) to Cu(I) in ligand complexes during transition into the gas phase, and these rules allow us to propose structural features of PA-Q complexes with copper ions in solution.
电喷雾串联质谱（ESI-MS/MS）提供了独特的机会，可以在接触后立即对有机磷农药（OP）喹硫磷（PA-Q）与过渡金属离子形成的复合物进行特征分析。这项研究补充了研究在过渡金属离子存在下喹硫磷水解的长期动力学的研究，并深入了解了溶液中初始配合物形成的结构特征。（水解反应：PA-Q+H2O→PA-OH+HQ，其中 PA-OH 是二乙基磷酸产物，HQ 是羟基喹喔啉。）
在混合后立即分析含有约 3 倍摩尔过量过渡金属离子的低微摩尔 PA-Q 溶液。通过提高去簇电势，以两种不同的方式实现了过渡金属离子与 PA-Q 的配合物的碎裂：首先，源内碎裂，其次，低能量碰撞诱导解离（CID）。
对于 Ag(+)，很容易观察到[PA-Q-Ag(+)]和相应的含 Ag(+)的降解产物离子。对于 Cu(2+)，我们观察到[PA-Q+Cu(2+)+NO3(-)]配合物离子的强度较弱，并且[2PA-Q+Cu(+)]和[PA-Q+Cu(+)]离子的信号很强，后两者归因于气相中从 Cu(II)到 Cu(I)的电荷态降低，表明 PA-Q 满足形成的配合物的特定结构要求，用于从溶液到气相的过渡过程中的电荷态降低。对于 Hg(2+)，[PA-Q+Hg(2+)+(PA-OH-H)(-)]离子是包含一个 Hg(2+)离子的最大观察到的物种。无法观察到 1:1 物种[PA-Q]或其他降解产物：Hg(2+)。
PA-Q 与过渡金属离子形成的配合物的 ESI-MS/MS 是一种强大的技术，可以探测这些配合物在溶液中的初始形成。来自其他小组的先前工作确定了结构要求，这些要求使配位化合物中的 Cu(II)在过渡到气相时能够降低到 Cu(I)，这些规则使我们能够提出 PA-Q 与铜离子在溶液中的配合物的结构特征。
