Seip Knut Fredrik, Faizi Moheba, Vergel Cristina, Gjelstad Astrid, Pedersen-Bjergaard Stig
School of Pharmacy, University of Oslo, P.O. Box 1068, Blindern, 0316, Oslo, Norway.
Anal Bioanal Chem. 2014 Mar;406(8):2151-61. doi: 10.1007/s00216-013-7418-8. Epub 2013 Oct 18.
The current work presents a large systematic screening of 61 possible organic solvents used as supported liquid membranes (SLM) in electromembrane extraction (EME). For each organic solvent, recovery, current across the SLM, and stability considerations have been investigated and correlated to relevant solvent properties through partial least square regression analysis. The five unpolar basic drugs pethidine, haloperidol, methadone, nortriptyline, and loperamide were used as model analytes. Efficient EME solvents were found to have a low water solubility (<0.5 g L(-1)) and belonged to cluster 2 of a Kamlet-and-Taft-based solvent classification system (high dipole moments and proton acceptor properties). These parameters were especially found in nitroaromatic compounds and ketones. Small molecules with low log P value and high water solubility were unsuitable, as they tended to give unstable extractions, caused by a high current across the SLM. This was often combined with substantial solvent-related interferences and the generation of an electroosmotic flow across the SLM, with resulting acceptor solution expansion. Large molecules with a high log P value were classified as inefficient. For these solvents, no current was measured across the SLM and no analytes were extracted. This is the first time systematic knowledge on the SLM in EME has been gathered and investigated, and the presented results could be highly beneficial for future development and optimization of EME.
当前工作对61种可能用作电膜萃取（EME）中支撑液膜（SLM）的有机溶剂进行了大规模系统筛选。对于每种有机溶剂，研究了回收率、跨支撑液膜的电流以及稳定性因素，并通过偏最小二乘回归分析将其与相关溶剂性质进行关联。使用了五种非极性碱性药物哌替啶、氟哌啶醇、美沙酮、去甲替林和洛哌丁胺作为模型分析物。发现高效的电膜萃取溶剂具有低水溶性（<0.5 g L⁻¹），且属于基于Kamlet和Taft的溶剂分类系统中的第2类（高偶极矩和质子受体性质）。这些参数在硝基芳烃化合物和酮类中尤为常见。低log P值和高水溶性的小分子不适用，因为它们往往会导致不稳定的萃取，这是由跨支撑液膜的高电流引起的。这通常伴随着大量与溶剂相关的干扰以及跨支撑液膜产生电渗流，从而导致接受相溶液膨胀。高log P值的大分子被归类为低效。对于这些溶剂，未测量到跨支撑液膜的电流，也未萃取到分析物。这是首次收集并研究关于电膜萃取中支撑液膜的系统知识，所呈现的结果可能对电膜萃取的未来发展和优化非常有益。
