Abstract

In this work, we investigated for the first time hydrophobic deep eutectic solvents (DES) as supported liquid membrane (SLM) for electromembrane extraction (EME). Camphor, coumarin, DL-menthol, and thymol were used as non-ionic DES components. Different DESs compositions were tested, to study systematically the importance of hydrogen bonding and dispersion/aromatic interactions during mass transfer across the SLM. Unexpectedly, mixtures of coumarin and thymol were highly efficient SLMs, and provided exhaustive or near-exhaustive extraction of non-polar bases, non-polar acids, and polar bases. SLMs with such performance for both bases and acids, in a large polarity window, are not found in current literature. The SLMs were highly aromatic, very strong hydrogen bonding donors, and moderately strong hydrogen bonding acceptors. Aromatic (π type) interactions were apparently very important for transfer of bases, while hydrogen bonding were dominant for acids. EME of six polar basic drugs from plasma, with a coumarin and thymol mixture as SLM, and combined with UHPLC-MS/MS analysis, was evaluated to test the potential for analytical applications. Plasma was diluted 1:1 with phosphate buffer pH 2.0. Calibration curves were linear in the therapeutic ranges (0.970 < R2 < 0.999), recoveries ranged between 47 and 93%, and repeatability was within 1.6–10.7% RSD. The clean-up efficiency was excellent and no matrix effects from plasma were seen. Presence of trace levels of coumarin in the acceptor phase was however found to cause some ion enhancement. Based on the current work, we foresee more research on the use of DES in EME.

Highlights

  • Electromembrane extraction using deep eutectic solvents as the liquid membrane Frederik Andre Hansen a, 1, Elia Santigosa-Murillo b, 1, Maria Ramos-Payan c, María Mun~oz b, Elisabeth Leere Øiestad d, Stig Pedersen-Bjergaard a, e, *

  • The filter plate was subsequently clamped with the sample plate, and the sample solutions came into contact with the supported liquid membrane (SLM). 100 mL acceptor solution was pipetted into the filter plate in the reservoir above the SLM, and an aluminum lid with 96 electrode rods was attached

  • Solvents used as SLM in Electromembrane extraction (EME) should be non-volatile and water immiscible, to maintain SLM integrity during extraction

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Summary

Chemicals and reagents

Camphor, DL-menthol, coumarin, thymol, 4nitroaniline, 2-nitrophenyl octyl ether (NPOE), 1-octanol, phosphoric acid, pethidine hydrochloride, papaverine hydrochloride, promethazine hydrochloride, verapamil hydrochloride, amitriptyline hydrochloride, perphenazine, prochlorperazine dimaleate, ketoprofen, naproxen, flurbiprofen, fenoprofen calcium salt hydrate, diclofenac sodium salt, ibuprofen, tyramine, atenolol, metaraminol bitartrate, ephedrine hydrochloride, and metoprolol tartrate were purchased from Sigma-Aldrich (St. Louis, MO, USA). Methanol was from Merck (Darmstadt, Germany), and water was purified by a Milli-Q water purification system (Molsheim, France). Nile red (99%, ACROS OrganicsTM) was purchased from Fisher Scientific (Pittsburgh, PA, USA), and N,N-diethyl-4-nitroaniline was purchased from Fluorochem (Derbyshire, UK). Drug-free plasma was obtained from Oslo University Hospital (Oslo, Norway) and stored at À32 C

Preparation of deep eutectic solvents
Determination of Kamlet-Taft solvatochromic parameters
Calculations
Selection of deep eutectic solvents for SLMs and model system
Extraction of polar bases
Evaluation of analytical performance and matrix effects from human plasma
Conclusion
Full Text
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