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; Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark.
Anal Chim Acta. 2024 Apr 8;1297:342360. doi: 10.1016/j.aca.2024.342360. Epub 2024 Feb 16.
Electromembrane extraction (EME) involves the process of mass transfer of charged analytes from an aqueous sample through an organic liquid membrane into an aqueous acceptor medium under the influence of an electrical field. Successful solvation of the analyte within the liquid membrane is of paramount importance and involves molecular interactions with the liquid membrane. In this comprehensive investigation, parallel EME was examined using a training set of 13 model peptides employing deep eutectic solvents as the liquid membrane. These deep eutectic solvents were formulated by mixing specific monoterpenes (thymol, menthol, camphor) with medium-chain fatty acids (1-octanoic acid and 1-decanoic acid).
From an array of different liquid membrane compositions explored, it was revealed that the combination of camphor and 1-decanoic acid (in a 1:1 w/w ratio) with 2% di (2-ethylhexyl) phosphate (DEHP) delivered the most efficient extraction system. The solvation of the model peptides within this liquid membrane predominantly relied on ionic interactions between protonated basic functionalities and DEHP, along with hydrogen bond interactions between the deprotonated acid functionalities (hydrogen bond acceptor) and 1-decanoic acid (hydrogen bond donor). Selectivity was modulated by the pH of the sample and acceptor solutions, with a direct correlation to the polarity and net charge of the model peptides. The ionization of 1-decanoic acid in the interfacial region between the sample and liquid membrane emerged as an important factor influencing the selectivity.
Although parallel EME of peptides has been reported previously, the current liquid membrane provides an extraction system with sufficient stability for the first time. Selective extraction of peptides through EME holds substantial promise within the realm of next-generation environmentally-friendly sample preparation methodologies. The findings presented in this paper contribute significantly to our fundamental understanding of these processes, and may serve as an important reference for the development of future methods in this field.
电迁移萃取（EME）涉及带电分析物在电场的影响下从水性样品中通过有机液膜转移到水性接受介质中的质量传递过程。成功地将分析物溶解在液膜中至关重要，涉及与液膜的分子相互作用。在这项全面的研究中，使用混合特定单萜（麝香草酚、薄荷醇、樟脑）与中链脂肪酸（辛酸和癸酸）的深共晶溶剂作为液膜，对平行 EME 进行了检查。
在所探索的不同液膜组成中，发现樟脑和癸酸（1:1 w/w 比）与 2%二（2-乙基己基）磷酸酯（DEHP）的组合提供了最有效的萃取系统。模型肽在该液膜中的溶解主要依赖于质子化碱性官能团与 DEHP 之间的离子相互作用，以及去质子化酸官能团（氢键受体）与癸酸（氢键供体）之间的氢键相互作用。通过样品和接受溶液的 pH 值来调节选择性，与模型肽的极性和净电荷直接相关。在样品和液膜之间的界面区域中 1-癸酸的离解成为影响选择性的重要因素。
尽管以前已经报道过肽的平行 EME，但目前的液膜首次提供了足够稳定的萃取系统。通过 EME 选择性萃取肽在下一代环境友好型样品制备方法中具有很大的应用前景。本文提出的研究结果为我们对这些过程的基本理解做出了重要贡献，并可能成为该领域未来方法发展的重要参考。
