Journal of separation science最新文献

This paper aims to achieve efficient selective separation and green purification of menthol using green deep eutectic solvents (DESs). Taking peppermint essential oil as the research object, a green process based on in-situ formation of DESs is proposed to achieve efficient purification of menthol. Taking menthol in peppermint essential oil as a hydrogen bond donor (HBD), eight quaternary ammonium salts and quaternary phosphonium salts were screened as hydrogen bond acceptors (HBA), and tetrabutylammonium chloride (TBAC) was determined as the optimal HBA component. The hydrogen bonding between menthol hydroxyl and TBAC anion was confirmed by FT-IR and ¹H NMR characterization. After optimizing the conditions such as HBA type, n-hexane dosage, molar ratio, and vortex number, under the optimal conditions, the extraction recovery of peppermint essential oil reached 88.62% ± 0.82%, and the menthol purity was 91.16% ± 0.93%. Compared with the original peppermint essential oil, the menthol purity was significantly improved. The recycling experiment showed that TBAC has good reusability, a simple and green purification process, and good application prospects.

Trace detection of aspartame molecules is crucial for the safety management of additives in food. We developed a convenient synthetic method to prepare magnetic dummy molecularly imprinted polymers, innovatively using carbon nanotubes as the stick carrier of the adsorptive material, which can not only improve the physicochemical stability of the material, but also allow the magnetic microsphere core to disperse due to the presence of carbon nanotubes, thereby enhancing the adsorption performance of the material. Molecularly imprinted polymers were fixed as the shell on magnetic carbon nanotubes to improve the adsorption capacity of the adsorptive material for aspartame molecules. Aspartame in food was enriched by the developed magnetic solid-phase extraction method, followed by detection using LC-MS/MS. Meanwhile, the adsorption mechanism of aspartame by magnetic dummy molecularly imprinted polymers was discussed. Due to its strong selectivity and molecular recognition ability for aspartame, an ultra-low limit of detection was achieved after treatment with magnetic dummy molecularly imprinted polymers using the magnetic solid-phase extraction method, with a detection limit of 0.001 ng/g. This adsorption material can be reused five times. The developed method showed high applicability in detecting aspartame in various different food samples on the market, indicating that the method can be used for real samples to achieve trace detection of aspartame in food.

Monitoring trace levels of pesticide residues in water remains a major global analytical challenge. We synthesized a bio-derived hydrophobic deep eutectic solvent (DES), [thymol:tert-butylhydroquinone] (Thy:TBHQ), and coupled it with vortex-assisted dispersive liquid–liquid microextraction (DLLME) prior to gas chromatography (GC) with micro electron capture detection (µECD) for pre-concentration of organophosphorus pesticides (OPPs) (phosphamidon, diazinon, chlorpyrifos). DES formation and stability were confirmed by Fourier transform infrared spectroscopy (O–H red shift) and ¹H-NMR (deshielded phenolic signals). Univariate optimization identified acetonitrile (ACN) as a disperser and ACN/DES = 1:1 (v/v), 100 mL sample, 3 min extraction, and pH 2–6 as optimal. The method showed excellent linearity (coefficients of determination = 0.991–0.997), limits of detection (LODs) of 3.44–15.43 ng L⁻¹ and limits of quantification (LOQs) of 10.32–51.38 ng L⁻¹, all well below the EU 100 ng L⁻¹ per-pesticide limit, with enrichment factors of 13–27. Precision supported routine application (intra-day relative standard deviation [RSD] 1.67%–3.79%; inter-day 5.25%–9.66%). Spiked real samples across environmental waters: tap (≈90%–100% relative recovery), river (≈60%–82%), and seawater (≈54%–66%), each with RSD < 10% and no background residues detected. The DES retained >85% of its extraction performance over ≥9 adsorption–desorption cycles. Satisfactory extraction efficiency is probably due to the synergistic π–π, hydrogen bonding, van der Waals, and hydrophobic interactions between aromatic OPPs and the DES. Overall, the [Thy:TBHQ]-based vortex-assisted DLLME/GC with µECD platform delivers sensitive, precise, and reusable trace analysis with reduced solvent use, offering a green alternative for monitoring pesticides in diverse water matrices.

A simple, accurate, cost-effective, and sensitive analysis method for the determination of vancomycin in plasma samples has been reported using high-performance liquid chromatography-tandem mass spectrometry. UiO-66-NH₂ metal–organic framework was synthesized through a hydrothermal method, 5 mg of this compound was introduced into 5 mL of model solution or pretreated plasma adjusted to a pH of 8. The mixture was vortexed for 1 min and then the sorbent particles were separated by centrifugation. The upper phase of sorbents was removed and the analytes adsorbed were eluted by a 250 µL mixture of deionized water (pH 2) and methanol at a 1:1 ratio, v/v, under vortexing for 4 min from the sorbent surface. After centrifugation, the eluent was analyzed by the determination system. The synthesized nanoparticles underwent characterization using X-ray diffraction, Fourier transform infrared spectrometry, and scanning electron microscopy. To achieve optimal efficacy, optimization was carried out at every stage of the project, encompassing adsorption, extraction, and desorption processes. Approved validation data consisting of method detection limit (22 and 225 ng/mL in deionized water and plasma, respectively) and limit of quantification (73 and 774 ng/mL in deionized water and plasma, respectively), a wide linear range of the calibration curve (73–250 ng/mL and 774–1250 ng/mL in deionized water and plasma, respectively), and low relative standard deviations for interday and intraday precisions (≤ 4.8%) were obtained by the method. The proposed method can be successfully applied in the analysis for the determination of vancomycin in plasma and deionized water samples.

In this study, poly(N-isopropylacrylamide-4-vinylphenylboronic acid) thermosensitive microcryogels with different magnetic amounts were prepared for immunoglobulin G (IgG) purification. After, the prepared magnetic thermosensitive microcryogels were characterized by scanning electron microscopy, Fourier transform infrared attenuated total reflectance spectroscopy, electron spin resonance spectrometer, and optical microscopy. IgG binding capacities were investigated using aqueous IgG solutions prepared at varying concentrations. The maximum IgG binding capacity of poly(N-isopropylacrylamide-4-vinylphenylboronic acid) thermosensitive microcryogels prepared with different magnetic amounts was calculated as 137 mg/g for microcryogels containing 23.0 mg Fe₃O₄, 72.0 mg/g for microcryogels containing 11.5 mg Fe₃O₄, 48.6 mg/g for microcryogels containing 5.62 mg Fe₃O₄, and 39.2 mg/g for microcryogels without Fe₃O₄ at pH 7.4 phosphate solution and 40°C. It was observed that poly(N-isopropylacrylamide-4-vinylphenylboronic acid) thermosensitive microcryogels can be reused ten times. According to the adsorption results, the adsorption of IgG onto the prepared magnetic poly(N-isopropylacrylamide-4-vinylphenylboronic acid) thermosensitive microcryogels fits the Langmuir isotherm model (Q_max: 147 mg/g, R²: 0.9976). After optimizing the experimental conditions, the purity of the eluted IgG was confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The developed microcryogels combine thermoreactivity with magnetic properties for efficient IgG purification, offering tunable binding capacities using boronic acid–based affinity.

Copper (Cu) is an essential trace element for maintaining normal cellular functions; however, excessive Cu accumulation has been confirmed to induce hepatotoxicity, while the metabolic mechanisms underlying Cu-induced hepatotoxicity remain unclear. In this study, an innovative integrated separation strategy was established, combining hydrophilic interaction liquid chromatography (HILIC) and reversed-phase liquid chromatography (RPLC), coupled with quadrupole-time-of-flight mass spectrometry (Q-TOF/MS), to systematically resolve metabolomic perturbations in CuCl₂-exposed rat BRL-3A hepatocytes. Based on their complementary separation mechanisms—HILIC enables efficient retention and separation of polar metabolites via hydrophilic interactions, while RPLC separates nonpolar/weakly polar lipid molecules based on hydrophobic interactions—this analytical strategy significantly expanded the coverage of detectable metabolites and improved the reliability of metabolite identification through cross-validation between the two chromatographic platforms. The results showed that a total of 25 metabolites with significant changes were identified when BRL-3A cells were exposed to 50 µM CuCl₂ (with a cell viability of 85%). These changes were mainly enriched in metabolic pathways such as glutathione metabolism (characterized by a significant decrease in the GSH/GSSG ratio, p < 0.01), arachidonic acid (AA) metabolism (a 42% reduction in AA, p < 0.05), and glycerophospholipid metabolism (a 1.8-fold increase in the levels of lysophospholipids [LysoPCs/LysoPEs], p < 0.05). These findings reveal that oxidative stress, membrane structure damage, and energy metabolism imbalance are the core mechanisms of Cu-induced hepatotoxicity. The integrated liquid chromatography-mass spectrometry (LC-MS) analytical framework established in this study not only provides a novel molecular perspective for elucidating the mechanisms of Cu-induced hepatotoxicity but also demonstrates the application potential of advanced complementary separation technologies in the risk assessment of environmental pollutants.

The separation and identification of components in complex mixtures is a requirement for any aspect of modern chemistry. The hyphenated technique of liquid chromatography (LC)–nuclear magnetic resonance spectroscopy (NMR) allows the combination of the separation capabilities of a liquid chromatograph with the structure elucidation capabilities of NMR. As this technique has developed, many approaches have been implemented, and this review aims to discuss these while addressing some of the practical considerations. An examination of the supporting strategies for LC–NMR is discussed, such as the development of solvent suppression methods, the design of more specialized NMR cells, or further hyphenation to other instrumentation such as a mass spectrometer. A sampling of relevant pharmaceutical and natural product applications is discussed that serve to highlight the utility of this technique and its relevancy and current status in the field.

The minor-disturbance method is a convenient route to adsorption isotherms, but the thermodynamic void volume extracted from its data is often taken—sometimes uncritically—to be the column's geometrical void. Here, we investigate the thermodynamic void volume using an adsorption-dividing-plane framework. This framework clarifies that the choice of any hold-up volume implicitly defines a Gibbs-like dividing surface, which in turn determines the thermodynamic meaning of the resulting isotherm. Experiments were performed on two contrasting media: a cyano-silica normal phase with C₂–C₄ alcohols and acetone, and an octyl-bonded reversed phase with acetonitrile, methanol, and acetone, each probed at 15 or more bulk concentrations. On the cyano column, all solutes yielded an identical thermodynamic void volume (≈2.98 mL), indicating the dividing plane aligns with the silica surface and the resulting isotherms represent true surface excess. In contrast, the thermodynamic void volume on the octyl-bonded column was solute-dependent (acetonitrile > acetone > methanol), reflecting probe-specific penetration into the bonded phase rather than the physical void volume. Negative branches observed in the high-concentration excess isotherms of acetonitrile and acetone are rationalized by a conceptual three-zone concentration profile in which brush-induced depletion exceeds interfacial adsorption. Reprocessing the reversed-phase data with a single, fixed void volume shifted the excess isotherms as predicted while leaving the total-uptake isotherms unchanged, demonstrating that total adsorption is independent of the definition of the excess dividing plane when the saturation point is used to define the dividing surface. The study clarifies the physical meaning of the thermodynamic void volume: it equals the geometrical void only for phases with negligible bonded layers, but becomes probe-specific on densely bonded reversed-phase materials, where it serves as a quantitative indicator of brush penetration. A fixed dividing plane is therefore essential for meaningful cross-solute comparison of excess isotherms and for reliable interpretation of minor-disturbance data.