Journal of separation science最新文献

An innovative approach combining electrochemistry with online quadrupole time-of-flight-mass spectrometry (EC-MS/MS) was employed to study the oxidative products and metabolic pathways of three bioactive compounds found in Phellodendri Chinensis Cortex, including phellodendrine, obaculactone, and obacunone. This advanced analytical technique provided detailed insights into their transformation processes. The simulation of phase I metabolism reactions was conducted within an electrochemical microreactor system. The heart of this apparatus was a reliably performing boron-doped diamond electrode. Meanwhile, a defined concentration of glutathione (GSH) was injected into the reaction system to obtain phase II metabolites. The metabolites were collected and concentrated for offline electrochemistry-ultra-high-performance liquid chromatography-quadrupole-time of flight-mass spectrometry analysis (EC-UHPLC-MS/MS). The main converted products and metabolic pathways were further verified through in vitro liver microsome incubation experiments. It was revealed that the simulated metabolic process based on the electrochemical system effectively produced a variety of metabolites from the compounds, which were subsequently compared with those obtained from rat liver microsomal incubations. Without matrix interference, the drug metabolic process could be effectively simulated and analyzed using the electrochemical system. The findings underscore the utility of electrochemistry as a robust tool for preliminary investigations into the metabolism of natural products, offering a reliable and efficient alternative to traditional methods.

The introduction of mass spectrometry in the analysis of pesticide residues has significantly enhanced analytical efficiency, reduced analysis times, and enabled ultra-trace detection. However, the matrix effect—wherein target analytes experience interference from the matrix during ionization—remains a critical issue. In multiresidue pesticide analysis via LC-MS/MS, matrix effects are typically addressed by preparing calibration standards through the dilution of matrix extracts with buffers (organic solvents) or by diluting the sample, which must be manually performed by the analyst. This study developed an automated matrix dilution injection (AMDI) method that leverages the autosampler built-in automatic dilution injection feature in liquid chromatography (LC) to prepare matrix-corrected dilutions and quantify analytes without manual manipulation. The AMDI method was validated by analyzing 71 pesticides in four agricultural commodities, where linearity, accuracy, and precision were assessed using two LC systems with different performances (HPLC-MS/MS and UHPLC-MS/MS). The AMDI method exhibited superior linearity in UHPLC analyses compared with conventional matrix-matched calibration standards. Furthermore, most of the pesticides analyzed exhibited measurement accuracies of 70%–120% and precision with relative standard deviations below 10%.

Countercurrent chromatography (CCC) is a liquid–liquid separation technique in which compounds are separated on the basis of partitioning between two immiscible phases. Besides having inherent advantages—high loading capacity, easy scale-up, and sample recovery with no chemical degradation—that position CCC as an alternative to conventional chromatographic methods, it can also be sustainable, especially when methodologies are optimized, including the use of eco-friendly solvents, high sample loading, and solvent recycling. This review highlights the green potential of CCC by integrating green chemistry principles through low solvent consumption, reduced waste, and the use of bio-based solvents, such as aqueous two-phase solvent systems and deep eutectic solvents, to align CCC with sustainable chromatographic approaches. Moreover, the technique's ability to recycle solvent phases and process crude extracts with minimal sample preparation boosts its environmental benefits. Despite these advantages, several challenges limit the widespread adoption of CCC, particularly in industrial settings. Patent analysis indicates that although CCC is commonly used to purify natural products, its role in sustainability-driven innovations remains relatively limited. The selection of biphasic solvent systems is a critical bottleneck, often requiring extensive experiments, which can result in excessive solvent use. Advances in computational methods have improved the selection of solvent systems, allowing for a more resource-efficient approach. By modeling phase interactions, these computational tools can predict partition coefficients and optimize solvent compositions, consequently reducing experimental waste. Future research should focus on integrating CCC into large-scale sustainable workflows to enhance its environmental viability in natural product chemistry.

The sol-gel method demonstrates significant potential for fabricating protein molecularly imprinted polymers (MIPs). In order to maintain good protein structure and provide more recognition functional groups during the preparation of protein MIPs. In this study, an exceptionally mild sol–gel protocol for protein MIPs synthesis was developed, in which no catalyst or organic solvent was employed and abundant recognition groups were introduced through in-situ derivatization. This method has been applied in the preparation of MIPs using lysozyme (lys) as a template. The developed MIPs exhibit high adsorption capacity and selectivity toward lys. The generation of the imprinting effect was successfully demonstrated by observing the surface morphology and evaluating the physical/chemical properties of the synthesized MIPs. In subsequent adsorption experiments, MIPs also showed excellent adsorption performance (389.85 mg/g) and quickly reached the adsorption equilibrium within 60 min. In addition, the selectivity of MIPs for lys was improved by the sol-gel imprinting process, and good reusability was observed after five adsorption-desorption cycles. The method was also successfully applied to isolate lys from egg white samples. This work demonstrates the great potential of the sol-gel strategy in the field of molecular imprinting.

This study developed an air-assisted liquid-liquid microextraction method using a primary amine-based supramolecular solvent (SUPRAS) and a monoterpenoid as a coacervation agent to determine two tricyclic antidepressants (amitriptyline and nortriptyline) from human plasma and urine samples prior to high-performance liquid chromatography analysis. The extraction of two antidepressant drugs was performed using a micellar solution of the primary amine (1-octylamine) as an amphiphile. A monoterpenoid (thymol) was utilized to initiate the coacervation process. The homogeneous solution of the SUPRAS was dispersed into the aqueous sample phase using air bubbles introduced through a syringe. The important characteristic of the suggested SUPRAS is the elimination of toxic solvents, such as tetrahydrofuran, and the removal of dispersive solvents. The experimental parameters, such as primary amine type, monoterpenoid type, extraction cycle number, and pH, were investigated. The limits of detection (signal-to-noise ratio [S/N] = 3) and quantification (S/N = 10) were achieved to be 0.5–0.6 and 1.5–1.8 µg/L with a linear range of 1.5–4000 and 1.8–4000 µg/L in urine and plasma samples. The percentage relative standard deviation values (n = 5) were 2.9%–3.5% for amitriptyline and 4.1%–4.2% for nortriptyline. The proposed method has been applied successfully to the spiked urine and plasma samples, achieving recoveries in the range of 93.1%–95.2%

Deep eutectic solvents (DESs), composed of hydrogen bond donors (HBDs) and hydrogen bond acceptors (HBAs), are efficient and widely applied solvents for extracting active compounds. Phlorizin (PHL), as the main component of Malus hupehensis, plays a critical role in the preparation of a DES-based extract. The appropriate option of DES is a primary consideration in the extraction of PHL from M. hupehensis. According to the chemical structural characteristics of PHL and solvent, the conductor-like screening model for real solvents is applied to select a DES. Lactic acid (LA) and betaine (BET) with a molar ratio of 2:1 and 40 wt% water are determined, and the extraction results are consistent with the predicted solubility of PHL in selected DESs. Thus, the optimal extraction conditions are identified as liquid-material ratio 40 mL/g, extraction time 50 min, and extraction temperature 60°C, resulting in the maximum yield of 14.07 ± 0.14%. As evidenced by Fourier-transform infrared and proton nuclear magnetic resonance spectra, PHL acts as an HBD and competitively interacts with HBA sites that are occupied by LA. Molecular dynamics simulations demonstrate the hydrogen bonding interactions between PHL and DES, consisting of LA and BET, with the lowest interaction energy of –135.6 kJ/mol. Therefore, the conductor-like screening model for real solvents is an available strategy to rapidly and efficiently select the appropriate DES on the basis of the thermodynamic characteristics. DESs can effectively extract PHL from M. hupehensis, and the DES-based extract of M. hupehensis with antioxidant activity provides a foundation for further application of DESs.

The growing environmental and health concerns regarding micro- and nanoplastics (MNPs) have prompted the development of advanced analytical methods for accurate characterization and quantification. Pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) enables polymer identification by their thermal destruction into characteristic fragments. However, the small particle size and interferences originating from complex sample matrices complicate its analysis. Therefore, the integration of comprehensive two-dimensional GC (GC×GC) would improve separation efficiency and sensitivity and provide a detailed composition of environmental and biological samples. This review documents (i) the evolution of Py-GC-MS and (ii) the potential to resolve overlapping compounds, improving quantification accuracy, and detecting minor plastic compounds and degradation byproducts by comprehensive GC×GC-MS as a crucial approach to measure MNPs. Despite the documented advancements, key challenges persist. The lack of standardized protocols for sample preparation and calibration, impeding the comparability of studies, is of prime concern. The massive presence of (in)organic interferences even further accentuates the absence of internal standards in terms of quantification. Therefore, to improve analytical reliability, future research should focus on developing standardized methodologies, improving detection sensitivity for NPs, and incorporating complementary approaches. Additionally, coupling GC×GC with time-of-flight MS further strengthens its capability to provide higher analytical resolution power and better chemical description of pyrolyzates. This review highlights the crucial role of advanced Py and chromatography-based techniques in supporting the analytical description of the extent of plastic pollution and in supporting evidence-based policymaking and successful mitigation efforts to protect ecosystems and public health.

Herbicides seriously threaten the ecosystem due to their wide application and environmental migration. Nevertheless, the detection and confirmation methods of triazine herbicides and their degradation products in seawater matrix remain deficient, which affect the accuracy of marine environment and aquatic organism safety risk assessment. In the present study, rapid analysis and accurate identification of seven triazine herbicides and six degradation products in seawater were achieved for the first time, based on hydrophilic-lipophilic balance solid-phase extraction combined with scanning pattern of full scan mass spectrometry-data-dependent mass spectrometry² and internal standard calibration by liquid chromatography coupled with Quadrupole/Exactive Orbitrap high-resolution mass spectrometry. The results showed a good linear relationship for the tested compounds with R² > 0.995. The limits of detection and quantitation of the method were 5.0 and 20 ng/L, respectively. The recoveries of the 13 compounds ranged from 70.0% to 120% when spiked at three levels, and the relative standard deviations were all less than 15% (n = 6). This method has been successfully applied to the detection of triazine herbicide in 34 real seawater samples, and the presence of prometryn, 2-hydroxy prometryn, desisopropyl prometryn, atrazine, and desisopropyl atrazine in positive seawater samples was confirmed by Quadrupole/Exactive Orbitrap high-resolution mass spectrometry. Therefore, the present method has promising application prospects in the detection and positive identification of pollutants in seawater, with high accuracy, sensitivity, and good reproducibility.

Matrix effects in gas chromatography (GC) are typically regarded as an analytical drawback, as co-eluting compounds can distort analyte quantification. This study demonstrates that a transient matrix effect can be deliberately induced to enhance GC–MS sensitivity for environmental pollutants. Four classes of high-boiling protectants—alcohols, amines, carboxylic acids, and polyethylene glycols (PEGs)—were systematically evaluated for their ability to increase detector response for polycyclic aromatic hydrocarbons (PAHs), chlorophenols, and nitrophenols. The influence of protectant type, sample solvent, injector temperature, and initial column temperature on signal enhancement was investigated. Among all protectants, PEGs yielded the highest improvements, with average signal increases of 280% for PAHs and 380% for chlorophenols and nitrophenols. The transient nature of the effect was confirmed through alternating injections, ensuring no cumulative influence on subsequent analyses. Application of the QuEChERS method to water and soil samples showed comparable enhancements, with minimal interference from matrix components. Method validation for PEG-400 confirmed excellent linearity (R² > 0.998), two- to threefold lower LODs, and high precision (RSD < 4.3%), demonstrating robustness and reproducibility. Leveraging a controlled transient matrix effect, this approach achieves several-fold improvement in detection limits without altering chromatographic hardware, providing a simple and adaptable tool for trace-level environmental monitoring.