School of Pharmacy, University of Oslo, P.O. Box 1068, Blindern, 0316 Oslo, Norway.
Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark.
Anal Chim Acta. 2017 Aug 29;983:121-129. doi: 10.1016/j.aca.2017.05.038. Epub 2017 Jun 19.
A triple-flow electromembrane extraction (EME) probe was developed and coupled directly to electrospray-ionization mass spectrometry (ESI-MS). Metabolic reaction mixtures (pH 7.4) containing drug substances and related metabolites were continuously drawn (20 μL/min) into the EME probe in one flow channel, and mixed inside the probe with 7.5 μL min of 1 M formic acid as make-up flow from a second flow channel. Following this acidification, the drug substances and their related metabolites were continuously extracted by EME at 400 V, across a supported liquid membrane (SLM) comprising 2-nitrophenyl octyl ether (and for some experiments containing 30% triphenyl phosphate (TPP)), and into 20 μL min of formic acid as acceptor phase, which was introduced through a third flow channel. The acceptor phase was pumped directly to the MS system, and the ion intensity of extracted analytes was followed continuously as function of time. The triple-flow EME probe was used for co-extraction of positively charged parent drugs and their zwitterionic drug metabolites (hydroxyzine and its carboxylic acid metabolite cetirizine; and vortioxetine and its carboxylic acid metabolite Lu AA34443). While the zwitterionic metabolites could not be extracted at pH 7.4, it was shown that by acidifying the sample solution the zwitterionic metabolites could be extracted effectively. Various extraction parameters like make-up flow, extraction voltage and SLM composition were optimized for simultaneous extraction of parent drugs and metabolites. It was found that TPP added to the SLM improved extraction efficiencies of certain drug metabolites. Finally the optimized and characterized triple-flow EME probe was used for online studying the in-vitro metabolism of hydroxyzine and vortioxetine by rat liver microsomes. Due to the automated pre-extraction acidification of the rat liver microsomal solutions, it was possible to continuously monitor formation of the zwitterionic drug metabolites. As the triple-flow EME probe allowed modification of the pH of the sample without changing the pH in the bulk sample, the system can potentially be used for direct analysis of various kinds of chemical reactions that have to be run at pH conditions unfavorable for direct analyte extractions.
开发了一种三流通电膜萃取（EME）探头，并将其直接与电喷雾电离质谱（ESI-MS）耦合。在一个流道中，连续（20μL/min）将含有药物物质和相关代谢物的代谢反应混合物（pH 7.4）吸入 EME 探头中，并用来自第二个流道的 7.5μL/min 的 1M 甲酸作为补充流在探头内混合。在这种酸化之后，药物物质及其相关代谢物通过 EME 在 400V 下连续萃取，跨越包含 2-硝基苯辛醚的支撑液膜（SLM）（对于某些实验还包含 30%三苯基膦（TPP）），并进入 20μL/min 的甲酸作为接受相，该接受相通过第三个流道引入。接受相被直接泵入 MS 系统，并连续监测提取分析物的离子强度随时间的变化。三流通电膜萃取探头用于同时萃取带正电荷的母体药物及其两性离子药物代谢物（羟嗪及其羧酸代谢物西替利嗪；文拉法辛及其羧酸代谢物 Lu AA34443）。虽然两性离子代谢物在 pH 7.4 下无法被萃取，但结果表明通过酸化样品溶液可以有效地萃取两性离子代谢物。优化了各种萃取参数，如补充流、萃取电压和 SLM 组成，以实现母体药物和代谢物的同时萃取。结果表明，向 SLM 中添加 TPP 可以提高某些药物代谢物的萃取效率。最后，对优化和表征的三流通电膜萃取探头用于在线研究羟嗪和文拉法辛在大鼠肝微粒体中的体外代谢。由于大鼠肝微粒体溶液的自动预萃取酸化，可以连续监测两性离子药物代谢物的形成。由于三流通电膜萃取探头允许在不改变样品总体 pH 的情况下修改样品的 pH，因此该系统有可能用于直接分析各种需要在不利于直接分析物萃取的 pH 条件下进行的化学反应。
