annehay

• Hay, Anne Oldeide & Hansen, Frederik Andre (2025). Electromembrane extraction of tetracyclines in foods and human plasma prior to LC-MS/MS analysis: Impact of sample matrix on extraction performance. Advances in Sample Preparation. 17. doi: 10.1016/j.sampre.2025.100227. Full text in Research Archive
• Dowlatshah, Samira; Hay, Anne Oldeide; Noreng, Line & Hansen, Frederik Andre (2025). A practical tutorial for optimizing electromembrane extraction methods by response surface methodology. Advances in Sample Preparation. 14. doi: 10.1016/j.sampre.2025.100170. Full text in Research Archive Show summary

  Microextraction techniques, such as electromembrane extraction (EME), have greatly advanced analytical chemistry by providing efficient, cost-effective, and eco-friendly sample preparation methods. EME is especially promising for ionizable analytes, with its success relying on optimizing multiple experimental variables. Traditionally, optimization has employed a one-variable-at-a-time (OVAT) approach, which is time-consuming and may overlooks variable interactions. This tutorial introduces response surface methodology (RSM) as a superior alternative for optimizing EME methods. RSM allows for the simultaneous variation of multiple factors, offering a comprehensive understanding of their effects and interactions with fewer experiments. This tutorial covers the fundamental principles of EME, essential experimental parameters, and the application of RSM for method optimization. It includes guidance on software selection, design choice, factor settings, response definition, and the optimization of multiple responses. Practical steps for conducting experiments, analyzing data, and interpreting models are detailed, with real-life examples illustrating the process. The tutorial aims to make RSM accessible to both novice and moderately experienced users, promoting its broader application in analytical chemistry. By simplifying the complex optimization process, this tutorial supports the development of robust, efficient, and green EME methods.

• Song, Chenchen; Zhou, Chen; Hansen, Frederik Andre; Hay, Anne Oldeide & Pedersen-Bjergaard, Stig (2024). Optimization of generic conditions for electromembrane extraction of basic substances of moderate or low polarity. Journal of Separation Science. ISSN 1615-9306. 47(3). doi: 10.1002/jssc.202300801. Full text in Research Archive Show summary

  Generic electromembrane extraction (EME) methods were developed and optimized for basic analytes of moderate or low polarity, employing prototype conductive vial EME equipment. Two generic methods, B1 and B2, were devised for mono- and dibasic compounds with distinct polarity windows: 2.0 < log P < 6.0 for B1 and 1.0 < log P < 4.5 for B2. In B1, 10 μL of 2-nitrophenyl octyl ether served as the liquid membrane, while B2 utilized 10 μL of 2-undecanone. Both methods involved the acidification of 125 μL of human plasma samples with 125 μL of sample diluent (0.5 M HCOOH for B1 and 1.0 M HCOOH for B2). The acceptor phase consisted of 250 μL of 100 mM HCOOH. Extraction was conducted for 30 min with agitation at 800 rpm, employing an extraction potential of 100 V for B1 and 50 V for B2. A set of 90 pharmaceutical compounds was employed as model analytes. Both B1 and B2 demonstrated high recoveries (40%–100%) for the majority of model analytes within their respective polarity windows. Intra-day precision was within 2.2% and 9.7% relative standard deviation. Both extraction systems exhibited stability in terms of current, matrix effect values were between 90% and 109%.

• Hay, Anne Oldeide & Hansen, Frederik Andre (2024). Exploring electromembrane extraction coupled to fast LC-MS/MS as a high-throughput platform for determination of 12 polar endogenous metabolites in human plasma. Journal of Chromatography A. ISSN 0021-9673. 1737. doi: 10.1016/j.chroma.2024.465451. Full text in Research Archive Show summary

  High efficiency in the analytical workflow, including fast sample preparation and LC-MS/MS analysis, is an advantage when analyzing a high number of samples. It can however be a challenge when determining polar analytes in complex, biological samples, and one must expect to make a compromise between a simple sample preparation followed by a long chromatographic separation, or vice versa, to limit matrix effects. In this proof-of-concept work, a one-step 96-well (parallel extraction) electromembrane extraction (EME) method was coupled to flow injection-MS/MS of 0.7 min per sample, allowing a very high-throughput analysis of 12 polar, endogenous metabolites from unprecipitated plasma of limited dilution. The throughput of the EME method matched the subsequent analysis. Recoveries ranged from 6 to 93 %, and repeatability and linearity were 2–15 % and R2 ≥ 0.9949, respectively, for all but two compounds. Matrix effects were approximately 50 % after EME and varied <11 % between 6 plasma donors, which represented a major improvement relative to a simple protein precipitation where signals were entirely suppressed. The work demonstrates a potential for EME coupled to flow injection-MS/MS to serve as a high-throughput platform for bioanalysis, not just of polar analytes, but also hydrophobic drugs both basic and acidic.

• Song, Chenchen; Dowlatshah, Samira; Gaznawi, Somayeh; Hay, Anne Oldeide; Hasvold, Grete & Hansen, Frederik Andre (2024). New robust and efficient liquid membranes for conductive vial electromembrane extraction of acids with low to moderate hydrophilicity in human plasma. Analytical and Bioanalytical Chemistry. ISSN 1618-2642. doi: 10.1007/s00216-024-05503-6. Full text in Research Archive Show summary

  The current paper reports two new, robust, and efficient conditions for electromembrane extraction of acidic substances from human plasma. Two systems were developed based on eutectic solvents: A1 (“A” for acid) comprised dodecyl methyl sulfoxide and thymol in 1:2 ratio (w/w) as liquid membrane, while A2 used [6-methylcoumarin:thymol (1:2)]:2-nitrophenyl octyl ether in 2:1 ratio (w/w). The performance of A1 and A2 was characterized by extraction of 31 acidic model analytes (pharmaceutical drugs and nutrients) spiked into 100 µL human plasma diluted 1:1 (v/v) with phosphate buffer pH 7.4. The acceptor solution was 50 mM NH4HCO3 buffer pH 10.0, and extraction was performed at an agitation rate of 750 RPM. Voltage and extraction time were 30 V for 30 min and 10 V for 20 min for A1 and A2, respectively. Under optimal conditions, A1 extracted analytes with 1.8 ≤ log P ≤ 6.0 with an average recovery (R) of 85.1%, while A2 extracted in a range of 0.5 ≤ log P ≤ 6.0 with an average recovery of 79.9%. Meanwhile, extraction current was low at 9 and 26 µA, respectively, which is indicative of good system robustness. Using UHPLC-MS/MS analysis of the acceptor solution, repeatability of the A1 and A2 methods was determined to be 2.8–7.7% and 3.3–9.4% for R > 40%, matrix effects were 82–117% and 84–112%, respectively, and linear calibration curves were obtained. The performance and compatibility with human plasma represent a major improvement over previous state-of-the-art liquid membranes for acidic analytes, namely 1-octanol.

• Zhou, Chen; Dowlatshah, Samira; Hay, Anne Oldeide; Schüller, Maria; Pedersen-Bjergaard, Stig & Hansen, Frederik Andre (2023). Generic Liquid Membranes for Electromembrane Extraction of Bases with Low or Moderate Hydrophilicity. Analytical Chemistry. ISSN 0003-2700. 95(23), p. 8982–8989. doi: 10.1021/acs.analchem.3c01052. Full text in Research Archive Show summary

  For the first time, this paper introduces the idea of generic extraction conditions in electromembrane extraction (EME), where the selection of the liquid membrane is based on the charge (z) and hydrophobicity (log P) of the analyte. A broad range of organic solvents were tested as liquid membranes, and 90 basic pharmaceuticals were used as model analytes (−4.2 < log P < 8.1). 2-Nitrophenyl octyl ether (NPOE) was confirmed as a highly efficient liquid membrane for mono- and dibases (+1.0 ≤ z ≤ +2.0) of low polarity in the log P range of 2.2–6.4. This log P range was set as the extraction window (operational range) of NPOE. NPOE provided very high operational stability. At 50 V, the current was at a 1 μA level, and gas formation and drifting pH due to electrolysis were insignificant. 2-Undecanone was discovered as a new and robust alternative. This solvent extracted monobasic analytes (z = +1) in the log P range of 1.0–5.8 and was efficient even for bases of moderate polarity. The current was at the 1–3 μA level when 2-undecanone was operated at 50 V. Tri(pentyl) phosphate emerged as another new alternative for bases in the log P range of 0.5 to 5.5, providing greater selectivity differences. This solvent provided a higher current (30–50 μA), but the EME system stability was not compromised. 2-Undecanone and tri(pentyl) phosphate extracted protonated bases mainly by hydrogen bond interactions. NPOE, on the other hand, extracted based on a combination of hydrogen bond and π-type interactions and was consequently less selective.

• Hay, Anne Oldeide; Hansen, Frederik Andre; Psillakis, Elefteria & Pedersen-Bjergaard, Stig (2022). Liquid-phase microextraction in bioanalysis – How green can it be? Green Analytical Chemistry. 3. doi: 10.1016/j.greeac.2022.100028. Full text in Research Archive
• Hay, Anne Oldeide; Trones, Roger; Herfindal, Lars; Skrede, Silje & Hansen, Frederik Andre (2022). Determination of methotrexate and its metabolites in human plasma by electromembrane extraction in conductive vials followed by LC-MS/MS. Advances in Sample Preparation. 2. doi: 10.1016/j.sampre.2022.100011. Full text in Research Archive

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