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Electromembrane extraction (EME) in small, stagnant and chip-like devices has the potential for future in-field operation. Literature briefly discuss such systems, but performance suffered from evaporative losses of sample and acceptor. To address this, the current paper reports electromembrane extraction (EME) of five basic drugs (model analytes) from aqueous buffer solutions and whole blood samples under stagnant conditions in a completely closed system. A laboratory-made polyoxymethylene (POM) well plate served as compartment for the sample solution, while a commercially available well filter plate was used to immobilize 2-nitrophenyl octyl ether (NPOE) as supported liquid membrane (SLM) and as closed compartment for the acceptor solution. Major design parameters (sample compartment and electrode geometry) and operational parameters (sample volume, voltage and extraction time) were investigated and optimized. Electrode geometry was not very critical, but extraction efficiency increased with decreasing sample volume. Extraction from 50 μL aqueous buffer solution for 60 min and with a voltage of 75 V was considered exhaustive (sample was depleted), with recoveries ranging between 75% and 87% for loperamide, haloperidol, methadone, nortriptyline, and pethidine (RSD: 2-12%). Extraction from whole blood samples under optimized conditions yielded slightly lower recoveries, ranging between 57 and 96% (RSD: 3-12%). Stagnant EME was evaluated in combination with liquid chromatography-mass spectrometry (LC-MS) as a highly specific instrumental method, and provided evaluation data on methadone from blood samples in accordance with regulatory requirements (LOD: 0.4 ng/mL, LOQ: 1.4 ng/mL, RSD: 6-20%). This work has improved upon the design of stagnant EME, moving it further towards a viable in-field operation device., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Novel freezing solutions are constantly being developed to reduce quality loss in meat production chains. However, there is limited focus on identifying the sensitive analytical tools needed to directly validate product changes that result from potential improvements in freezing technology. To benchmark analytical tools relevant to meat research and production, we froze pork samples using traditional (-25 °C, -35 °C) and cryogenic freezing (-196 °C). Three classes of analyses were tested for their capacity to separate different freeze treatments: thaw loss testing, bioelectrical spectroscopy (nuclear magnetic resonance, microwave, bioimpedance) and low-temperature microscopy (cryo-SEM). A general effect of freeze treatment was detected with all bioelectrical methods. Yet, only cryo-SEM resolved quality differences between all freeze treatments, not only between cryogenic and traditional freezing. The detection sensitivity with cryo-SEM may be explained by testing meat directly in the frozen state without prior defrosting. We discuss advantages, shortcomings and cost factors in using analytical tools for quality monitoring in the meat sector., (Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Over the last four decades, there has been a pursuit for a non-invasive solution for glucose measurement, but there is not yet any viable product released. Of the many sensor modalities tried, the combination of electrical and optical measurement is among the most promising for continuous measurements. Although non-invasive prediction of exact glucose levels may seem futile, prediction of their trends may be useful for certain applications. Hypoglycemia is the most serious of the acute complications in type-1 diabetes highlighting the need for a reliable alarm, but little is known about the performance of this technology in predicting hypoglycemic glucose levels and associated trends. We aimed to assess such performance on the way to develop a multisensor system for detection of hypoglycemia, based on near-infrared (NIR), bioimpedance and skin temperature measurements taken during hypoglycemic and euglycemic glucose clamps in 20 subjects with type-1 diabetes. Performance of blood glucose prediction was assessed by global partial least squares and neural network regression models using repeated double cross-validation. Best trend prediction was obtained by including all measurements in a neural network model. Prediction of glucose level was inaccurate for threshold-based detection of hypoglycemia, but the trend predictions may provide useful information in a multisensor system. Comparing NIR and bioimpedance measurements, NIR seems to be the main predictor of blood glucose while bioimpedance may act as correction for individual confounding properties., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Open tubular liquid chromatography columns with organic polymer layers can be powerful tools for high sensitivity measurements in e.g. proteomics. However, these narrow columns are challenging to characterize. A two-electrode system, often used for bioimpendance measurements, was used to study poly(styrene-co-divinylbenzene = PS-DVB) polymer layered open tubular (PLOT) liquid chromatography columns with 10 μm inner diameters. The system performed electrical resistance measurements (ERM) for assessing layer thickness and porosity. Layer determination results were comparable (but more precise) to that obtained with scanning electron microscopy (SEM). Porosity examinations with ERM casted doubt on the presence/availability of pores in the layers investigated., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Different phosphate-, acetate- and formate buffers in the pH range 2.0-6.8 were tested for electromembrane extraction (EME) in a 96-well system. The five basic drugs haloperidol, loperamide, methadone, nortriptyline, and pethidine were selected as model analytes. The EME performance was tested with respect to extraction recovery, extraction current and pH-stability. The analytes were extracted from 200 μL buffer, through a 100 μm thick supported liquid membrane (SLM) of 2-nitrophenyl octyl ether (NPOE) immobilized in the pores of filters in a 96-well plate, and into 100 μL buffer acceptor phase. The extraction voltage was 50 V and the extraction time was 10 min. The acceptor phase was analyzed by HPLC-UV. The extraction current was ≤6 μA with all buffers, and pH was effectively stabilized during EME using buffers as donor (sample) and acceptor phase. For buffers with pH ≤ 4.8 as acceptor phase, the extraction recoveries were in the range 66-97% and with RSD <15%. With pH in the range 5.8-6.8 in the acceptor phase, the extraction recoveries decreased and were in the range 21-62%. This was attributed to elevated pH conditions in the acceptor/SLM interface. The presence of elevated pH conditions was visualized with phenolphthalein as pH sensitive color indicator. Increasing the buffer strength from 10 to 500 mM in an attempt to offset the elevated pH conditions gave no improvement, and elevated pH conditions remained. Elevated pH conditions in the acceptor/SLM interface were also observed when voltage was increased, and when NPOE was replaced with tributyl phosphate as SLM. The presence of elevated pH conditions close to the SLM in EME was discussed for the first time, and this information is highly important for future development of EME., (Copyright © 2017 Elsevier B.V. All rights reserved.)