Department of Pharmacy, University of Oslo, P.O. Box 1068 Blindern, 0316 Oslo, Norway.
Department of Pharmacy, University of Oslo, P.O. Box 1068 Blindern, 0316 Oslo, Norway; Oslo University Hospital, Division of Laboratory Medicine, Department of Forensic Sciences, P.O. Box 4459 Nydalen, 0424, Oslo, Norway.
J Chromatogr A. 2022 Feb 8;1664:462769. doi: 10.1016/j.chroma.2021.462769. Epub 2021 Dec 23.
The present paper defines the optimal extraction window (OEW) for three-phase membrane-based liquid-phase microextraction (MP-LPME) in terms of analyte polarity (log P), and anchors this to existing theories for equilibrium partitioning and kinetics. Using deep eutectic solvents (DES) as supported liquid membranes (SLM), we investigated how the OEW was affected by ionic-, hydrogen bond and π-π interactions between the SLM and analyte. Eleven basic model analytes in the range -0.4 < log P < 5.0 were extracted by MB-LPME in a 96-well format. Extraction was performed from 250 µL standard solution in 25 mM phosphate buffer (pH 7.0) into 50 µL of 10 mM HCl acceptor solution (pH 2.0) with mixtures of coumarin, camphor, DL-menthol, and thymol, with and without the ionic carrier di(2-ethylhexyl) phosphate (DEHP), as the SLM. The OEW with pure DES was in the range 2 < log P < 5, and low SLM aromaticity was favorable for the extraction of non-polar analytes. Here, extraction recoveries up to 98% were obtained. Upon addition of DEHP to the SLMs, the OEW shifted to the range -0.5 < log P < 2, and a combination of 5% DEHP and moderate aromaticity resulted in extraction recoveries up to 80% for the polar analytes. Extraction with ionic carrier was inefficient for the non-polar analytes, due to excessive trapping in the SLM. The results from our study show that LPME performs optimally in a relatively narrow log P-window of ≈ 2-3 units and that the OEW is primarily affected by ionic carrier and aromaticity.
本文根据分析物的极性（log P）定义了三相膜液-液微萃取（MP-LPME）的最佳萃取窗口（OEW），并将其与现有的平衡分配和动力学理论联系起来。使用深共晶溶剂（DES）作为支撑液膜（SLM），我们研究了 SLM 和分析物之间的离子、氢键和π-π相互作用如何影响 OEW。通过 MB-LPME，在 96 孔格式中从 250µL 标准溶液（25mM 磷酸盐缓冲液（pH 7.0））中提取了 11 种基本模型分析物，进入 50µL 10mM HCl 接受溶液（pH 2.0），混合物中含有香豆素、樟脑、DL-薄荷醇和百里酚，有和没有离子载体二（2-乙基己基）磷酸酯（DEHP）作为 SLM。纯 DES 的 OEW 范围为 2<log P<5，低 SLM 芳构性有利于非极性分析物的萃取。在这里，提取回收率高达 98%。在 SLM 中加入 DEHP 后，OEW 移至-0.5<log P<2 的范围，5% DEHP 和适度的芳构性的组合导致极性分析物的提取回收率高达 80%。由于在 SLM 中过度捕获，离子载体萃取对非极性分析物效率不高。我们的研究结果表明，LPME 在约 2-3 个单位的相对较窄的 log P 窗口中表现最佳，OEW 主要受离子载体和芳构性的影响。
