J Chromatogr A [JOURNAL]
Sun
200 papers
Fluorine-functionalized covalent organic framework aerogels for online solid-phase extraction of bisphenols prior to chromatographic analysis.
Luo Y, Zhang X, Su B … +3 more , Zhang H, Feng J, Sun M
J Chromatogr A · 2026 Aug · PMID 42217393 · Publisher ↗
The accumulation of bisphenols through the food chain could cause severe harm to human health. Therefore, the sensitive detection of trace bisphenols in environment is very important for environmental monitoring and publ...
The accumulation of bisphenols through the food chain could cause severe harm to human health. Therefore, the sensitive detection of trace bisphenols in environment is very important for environmental monitoring and public health. Compared with offline extraction methods, online solid-phase extraction (SPE) displayed the advantages of convenient operation and high precision. Furthermore, extraction materials with satisfactory enrichment performance are the most important for online SPE. Covalent organic framework (COF) aerogels represent a novel class of advanced materials, and the introduction of functional groups can improve their properties. Hence, this work prepared a fluorinated COF aerogel (COF-A), a fluorine-free COF aerogel (COF-A) and a fluorinated COF powder (COF-P) at room temperature, which were characterized with SEM, XRD, XPS and other means. Some model analytes were selected to investigate these materials through online SPE, COF-A displayed highest enrichment factors (1130-2271) than other two materials, based on large surface area, hierarchical pore structure, and multiple interactions (π-stacking, hydrophobic, hydrogen-bonding and F-F interactions). Subsequently, COF-A was used as adsorbent to study adsorption performance toward bisphenols, and displayed the adsorption capacity of 157-195 mg/g for four bisphenols. The adsorption process was dominated by chemical adsorption according to the adsorption kinetics model. By coupling COF-A-based online SPE with high-performance liquid chromatography-diode array detection (HPLC-DAD), an online SPE-HPLC-DAD analytical method was established to detect bisphenols in water samples. Compared with other methods, the analytical method had lower detection limits (0.01-0.05 μg/L) and broad linear ranges (0.033-20.0 μg/L). The research introduced the COF-A for online enrichment and analysis of bisphenols, which broadened the application of COF aerogels in the sample preparation and environmental detection fields.
From design to application: chiral Cu based metal-organic frameworks for superior enantioselective resolution.
Liao D, Li H, Liu Z … +2 more , Fu H, Guo P
J Chromatogr A · 2026 Aug · PMID 42217392 · Publisher ↗
Increasing attention is being paid to ensuring that the therapeutically active enantiomer, rather than a racemic mixture, is administered in clinical treatment. Here we report a straightforward one-pot synthesis of a pai...
Increasing attention is being paid to ensuring that the therapeutically active enantiomer, rather than a racemic mixture, is administered in clinical treatment. Here we report a straightforward one-pot synthesis of a pair of chiral copper-based metal‑organic frameworks (Cu-MOFs) using Cu ions and modulator benzoic acid and 4,4'-((2,2-bis((pyridin-4-yloxy)methyl)propane-1,3-diyl)bis(oxy))dipyridine(TPOM), affording two enantiomeric frameworks designated 1 and 1'. In parallel, we prepared novel chiral nanocomposites (Cu-MOF@SiO) and introduced them as chiral stationary phases (CSPs) into an Agilent 1260 Infinity II empty HPLC column by a dry-loading procedure (referred to as column A). The chromatographic performance of column A is evaluated with racemic mixtures. Remarkably, column A successfully resolves more than ten pairs of commonly used drug enantiomers. These results demonstrate that the nanocomposite-functionalized column exhibits high enantioselectivity and excellent chiral resolution for a broad range of racemic analytes, especially alcohols and ketones.
Bionic phase-transitioned α-lactalbumin coating for efficient separation of structurally similar environmental endocrine disruptors by open tubular capillary electrochromatography.
Li L, Zhang M, Wang J … +6 more , Wu Y, Tian L, Zhang J, Chen H, Liu Y, Yang P
J Chromatogr A · 2026 Aug · PMID 42217391 · Publisher ↗
Environmental endocrine disruptors with estrogenic effects pose a significant threat to human health. However, many of these disruptors are homologues or isomers with similar structures, making them difficult to separate...
Environmental endocrine disruptors with estrogenic effects pose a significant threat to human health. However, many of these disruptors are homologues or isomers with similar structures, making them difficult to separate. Therefore, it is crucial to develop simple, rapid, and effective methods for their separation and detection. In this study, we developed a phase transition α-lactalbumin nanofilm (PTLA) using a fast phase transition preparation method. The nanofilm can stably adhere to various substrate surfaces and exhibits excellent stability under extreme conditions such as high-tack tape peeling, acid-alkali exposure, organic solvents, and high-pressure resistance. Its large specific surface area and abundant chemical groups enhance interactions with analytes. As a result, the PTLA-enhanced open tubular capillary electrochromatography (OT-CEC) achieved baseline separation of bisphenol homologs in 11 min and nitrophenol isomers in 7 min. Additionally, the PTLA-coated capillary demonstrated remarkable reusability, performing over 200 cycles with consistent peak shape and resolution. The relative standard deviations (RSDs) for intra-day, inter-day, and column-to-column repeatability were within 6.2%. Thus, PTLA coatings represent a significant advancement in separation science.
UPLC-Q-TOF-MS/MS-linked bioactivity-guided elucidation of tissue-specific chemical diversity in Tamarix austromongolica.
Guo J, Xu Z, Gao J … +3 more , Guo Y, Ho CT, Bai N
J Chromatogr A · 2026 Aug · PMID 42214144 · Publisher ↗
Tamarix austromongolica (TA), an endemic salt-tolerant tree species in northwestern China, remains largely unexplored in terms of its phytochemical composition. In this study, an untargeted metabolomics approach based on...
Tamarix austromongolica (TA), an endemic salt-tolerant tree species in northwestern China, remains largely unexplored in terms of its phytochemical composition. In this study, an untargeted metabolomics approach based on ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS), combined with multivariate statistical analysis, was employed for the first time to systematically characterize the metabolite profiles of six TA parts, namely roots, barks, stems, flowers, seeds, and leaves. A total of 105 metabolites belonging to 20 structural classes were identified, among which flavonoids accounted for 33% of the total metabolite pool. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) revealed significant tissue-specific distribution patterns of metabolomes across the six parts, with flavonoids identified as the core chemical markers driving inter-tissue differentiation. Parallel in vitro anti-inflammatory screening of extracts from the six parts demonstrated that the leaf extract (TAL) possessed the highest safety margin and potent NO inhibitory activity. Network pharmacology and molecular docking analyses indicated that three major flavonoids in TAL-Tricin, Quercetin-3-O-β-d-glucuronide (Q3GA), and Diosmetin-could form high-affinity complexes with MAPK3, a key target in the PI3K-Akt/NF-κB signaling pathway, and molecular dynamics simulations further validated the binding stability of these complexes. This study provides systematic analytical method support and a scientific basis for the phytochemical characterization, bioactive part screening, and quality marker discovery of TA.
Magnetic chitosan-based solid-phase extraction for the determination of pesticides in water samples.
Duan S, Sui J, Ma Q … +5 more , Zhang Z, Zhao W, Li S, Tao J, Zong S
J Chromatogr A · 2026 Aug · PMID 42214143 · Publisher ↗
In this study, a FeO/chitosan magnetic composite was synthesized via a co-precipitation method and applied to magnetic solid-phase extraction (MSPE) for the determination of four pesticides-chlorbenzuron, bifenthrin, λ-c...
In this study, a FeO/chitosan magnetic composite was synthesized via a co-precipitation method and applied to magnetic solid-phase extraction (MSPE) for the determination of four pesticides-chlorbenzuron, bifenthrin, λ-cyhalothrin, and deltamethrin-in water samples. The prepared composite exhibited typical superparamagnetic behavior, with a saturation magnetization of 18.26 emu g, enabling rapid solid-liquid separation within approximately 5 s under an external magnetic field. The extraction process was completed within 7 min. Compared with pristine chitosan, the specific surface area of the magnetic composite increased markedly from 0.8675 to 19.7250 m g. Abundant Fe-OH functional groups on the composite surface provided effective adsorption sites for the target pesticides. Good linearity was achieved for all analytes over the concentration range of 0.11-1000 μg L (R ≥ 0.9960). After four consecutive adsorption-desorption cycles, the composite maintained satisfactory recovery performance, demonstrating good reusability. These results indicate that the FeO/chitosan composite is an efficient and environmentally friendly adsorbent. The developed MSPE method offers a simple, rapid, and cost-effective approach for pesticide extraction and determination in water samples, with the added advantages of operational convenience and recyclability. Furthermore, adsorption mechanisms were systematically elucidated using FTIR, XPS, kinetic and isotherm analyses, revealing the involvement of non-covalent interactions (hydrogen bonding, Lewis acid-base interactions, electrostatic interactions, and hydrophobic effects), covalent coordination, and electron transfer. This study provides a valuable reference for the synthesis and application of related magnetic composites and offers mechanistic insights that support the development of green water treatment technologies.
Exploiting ligand-driven salt selectivity for aggregate retention: enhancing monomer resolution on a high elution pH Protein A membrane.
Menouar-Menari O, Guth J, Menstell P … +2 more , Hafiz S, Frech C
J Chromatogr A · 2026 Aug · PMID 42214142 · Publisher ↗
Protein A chromatography often requires product-compromising low-pH conditions to remove monoclonal antibody aggregates. While recent high-pH ligands and membrane architectures have shown to improve aggregate clearance,...
Protein A chromatography often requires product-compromising low-pH conditions to remove monoclonal antibody aggregates. While recent high-pH ligands and membrane architectures have shown to improve aggregate clearance, the underlying mechanism of how the ligand and the matrix each contribute to this separation remains unclear. Here, we evaluated a recombinant high-pH Protein A prototype ligand immobilized on a Natrix membrane and a bead-based resin. We found that the addition of NaCl across a wide concentration range substantially enhanced monomer-aggregate resolution in a dose-dependent manner. Elevated ionic strength caused a slight shift in monomer elution toward milder conditions while simultaneously driving the tight retention of the aggregate subpopulation. At concentrations ≥ 0.5 M NaCl, aggregates were retained so strongly that they required complete salt removal under low-pH conditions to elute. Comparative evaluation proved this divergent selectivity is intrinsically driven by the recombinant ligand's specific binding response to salt, rather than being a mass-transport artifact of the membrane format. Leveraging this mechanism, we developed a stepwise elution strategy achieving > 70 % aggregate reduction and > 90 % monomer yield at pH 5.0, independent of initial aggregate burden. Additionally, a HIC-like flow-through mode confirmed the preferential retention of higher-order multimers. Ultimately, this work demonstrates that modulating ionic strength on engineered ligands establishes a highly tunable, mild-pH strategy for the robust purification of aggregation-prone therapeutics.
In situ pH-responsive deep eutectic solvent for homogeneous liquid-liquid extraction of preservatives and an antioxidant from aqueous and oily matrices.
Liao FY, Weng JR, Feng CH
J Chromatogr A · 2026 Aug · PMID 42214141 · Publisher ↗
Preservatives and antioxidants are widely used in consumer products to inhibit microbial growth and oxidative degradation. However, their excessive use may pose potential health risks, highlighting the need for regulator...
Preservatives and antioxidants are widely used in consumer products to inhibit microbial growth and oxidative degradation. However, their excessive use may pose potential health risks, highlighting the need for regulatory control and reliable analytical methods to ensure safety and compliance. This study aimed to develop a simple, environmentally friendly, and unified sample preparation strategy based on a pH-responsive deep eutectic solvent (pH-DES) coupled with homogeneous liquid-liquid microextraction (HLLME). The method was applied to extract six preservatives and one antioxidant from aqueous and oily matrices, followed by analysis using narrow-bore high-performance liquid chromatography with UV detection. The pH-DES was generated in situ in the sample using 4-methylcyclohexanol as the hydrogen bond acceptor and decanoic acid as the hydrogen bond donor at a 1:1molar ratio. As the pH-responsive component, decanoic acid, together with 4-methylcyclohexanol, facilitates the selective capture of target analytes through hydrogen bonding and hydrophobic interactions. The developed method exhibited satisfactory linearity in both aqueous and oily matrices and was successfully applied to 15 commercial food, pharmaceutical, and cosmetic products, yielding good recoveries (90.6-104.6%). In addition, AGREEprep evaluation confirmed the green performance of the proposed method. Overall, the in situ pH-DES-HLLME approach provides a simple and environmentally friendly strategy for the extraction of preservatives and an antioxidant from complex real-world samples.
Optimised ligand exchange solvent extraction methodology for the determination of labile and inert forms of copper in environmental samples.
Stipanović N, Crmarić D, Mlakar M … +1 more , Bura-Nakić E
J Chromatogr A · 2026 Aug · PMID 42202435 · Publisher ↗
A recent study using a competitive ligand exchange solvent extraction (CLE-SE) method indicates that oceanic copper (Cu) exists in two distinct pools: a labile fraction dominating surface waters, likely produced by photo...
A recent study using a competitive ligand exchange solvent extraction (CLE-SE) method indicates that oceanic copper (Cu) exists in two distinct pools: a labile fraction dominating surface waters, likely produced by photochemical degradation of an inert pool, and a more stable inert fraction prevailing in the ocean interior. This finding challenges earlier studies and suggests that electrochemical characterisation may overestimate both the concentration and binding strength of natural Cu chelators. Here, we optimised the CLE-SE method using the artificial Cu ligand salicylaldoxime (SA). Assuming SA was present in sufficient excess to bind all exchangeable Cu, toluene was used to selectively extract Cu-SA complexes, presumably as the neutral Cu-SA bis-complex (Cu(HSA)). Extracted Cu was back-extracted with 10% nitric acid (HNO₃) and quantified by differential pulse anodic stripping voltammetry (DP-ASV). Method sensitivity of 100% (quantitative extraction of Cu) at SA concentrations ([SA]) above 10 μM was assessed using model solutions and an estuarine sample in the absence of organic ligands. Solution speciation was evaluated using thermodynamic modelling, spectroscopic observations, and extraction behaviour, supporting the dominance of Cu(HSA) at [SA] above 10 μM. The formation constant of Cu(HSA) (log K'') was determined by spectrophotometric reverse titration with ethylenediaminetetraacetic acid (EDTA). Application to estuarine samples revealed an inert Cu fraction representing 15-25% of total dissolved Cu ([Cu]), which did not exchange with SA, even at [SA] up to 100 µM. Redox speciation excluded Cu(I) as the source of inert behaviour, while ultrafiltration identified colloids as the dominant form of inert Cu.
In-line spectroscopic measurement of pH profiles using methyl orange: Application to pH transients in protein A chromatography.
Moser AR, Zha RH, Cramer SM
J Chromatogr A · 2026 Aug · PMID 42190346 · Publisher ↗
In this work, we developed a method using the pH indicator methyl orange and an in-line UV detector to obtain accurate pH profiles for chromatographic applications in the pH range from 3.2-4.5. A linear calibration was u...
In this work, we developed a method using the pH indicator methyl orange and an in-line UV detector to obtain accurate pH profiles for chromatographic applications in the pH range from 3.2-4.5. A linear calibration was used for conversion of the ratio of absorbances at two wavelengths to pH and the method was shown to be relatively insensitive to ionic strength and buffer composition over the range of conditions examined. Methyl orange pH profiles were then validated against both offline and in-line pH probes, as well as a buffer mixing model. The approach was extended to measurements with a protein A column using a small mixer downstream of the column to enable addition of methyl orange prior to UV detection while avoiding column exposure. This approach was then employed in concert with in-line conductivity measurements to examine pH transient effects in a variety of buffer systems, revealing a wide range of pH transient behavior. The rapid response time of methyl orange compared to conventional pH electrodes was shown to yield improved accuracy under certain conditions and the observed data shed light on pH transitions of interest in affinity chromatography.
Stereoselective neuroprotective activity and blood-brain barrier permeability of Schisandrin B enantiomers.
Qi X, Fang Z, Li S … +4 more , Wang S, Tao N, Xu H, Cui Y
J Chromatogr A · 2026 Aug · PMID 42190345 · Publisher ↗
Schisandrin B (Sch B), a major dibenzocyclooctadiene lignan from Schisandra chinensis, possesses a unique form of axial chirality and exhibits significant neuropharmacological properties. To address the formidable analyt...
Schisandrin B (Sch B), a major dibenzocyclooctadiene lignan from Schisandra chinensis, possesses a unique form of axial chirality and exhibits significant neuropharmacological properties. To address the formidable analytical challenge of resolving this rigid axial chiral scaffold in complex biological environments, a high-performance chiral HPLC platform was systematically developed. Superior resolution (Rs = 2.93) was achieved on a Chiralcel OD-RH column using a methanol-water (90:10, v/v) mobile phase. By coupling experimental optimization with molecular docking simulations, the separation mechanism was elucidated, revealing that specific hydrogen bonding and π-σ hydrophobic interactions between the cellulose-based chiral stationary phase (CSP) and the axial chiral framework are the primary driving forces for stereoselective recognition. To overcome the matrix-resolution trade-off, the method was optimized to ensure high sensitivity and minimal Ion Suppression in five distinct biological matrices, including lipid-rich brain tissue. Under multiple reaction monitoring (MRM) mode, the analytes were measured with high specificity (m/z 401.2→285.2). This robust analytical platform was then applied to investigate the stereoselective blood-brain barrier permeability and neuroprotective efficacy of Sch B. While R-Sch B showed superior antioxidant efficacy in PC12 cells, S-Sch B exhibited significantly higher brain-to-plasma ratios (2.31 vs. 1.49) and preferential central nervous system accumulation. These findings, facilitated by enantiomer-specific interactions with efflux transporters such as P-glycoprotein, highlight the critical role of chirality in drug disposition and provide a reliable analytical framework for the development of enantiomer-specific neuroprotective agents.
Step-growth grafted anion exchangers with hyperbranched polyglycerol modification for ion chromatography.
Zhang K, Lou C, Diao Q … +4 more , Ye M, Zhao Y, Ye H, Zhu Y
J Chromatogr A · 2026 Aug · PMID 42190344 · Publisher ↗
Herein, we report a step-growth approach to constructing polyelectrolyte-grafted stationary phases for ion chromatography (IC). Linear polyelectrolytes were covalently immobilized onto diol-functionalized substrate parti...
Herein, we report a step-growth approach to constructing polyelectrolyte-grafted stationary phases for ion chromatography (IC). Linear polyelectrolytes were covalently immobilized onto diol-functionalized substrate particles via cycled di-epoxide-mediated grafting, building up controllable functional layers. The materials can be packed and employed directly for IC, or further subjected to surface-initiated glycidol polymerization to introduce a hyperbranched polyglycerol overlayer, thereby improving stationary phase hydrophilicity. The modifications were verified by scanning electron microscopy, elemental analysis, Fourier-transform infrared spectroscopy, and N adsorption-desorption analysis. The correlations between chromatographic properties and synthetic variables were examined. The proposed anion exchangers were further evaluated for the separation of common inorganic anions, polarizable anions, organic acids, and nucleotides under suppressed IC conditions.
MMIP-assisted selective molecular depletion of icaritin-type aglycones for causality-guided metabolite identification in fermented Epimedium.
Li X, Hao B, Wang X … +7 more , Wang R, Tang W, Pan S, Yin W, Zhang M, Gao M, Zhang W
J Chromatogr A · 2026 Aug · PMID 42177853 · Publisher ↗
Establishing causal relationships between individual metabolites and biological activity in complex natural product systems remains a significant analytical challenge, as conventional chromatographic profiling is largely...
Establishing causal relationships between individual metabolites and biological activity in complex natural product systems remains a significant analytical challenge, as conventional chromatographic profiling is largely limited to correlation-based interpretation. In this study, a chromatography-guided analytical intervention strategy was developed based on a magnetic molecularly imprinted polymer (MMIP) to enable selective and quantitative manipulation of target metabolites in fermented Epimedium flavonoids. Time-resolved UPLC-MS/MS profiling revealed rapid microbial deglycosylation of prenylated flavonoid glycosides, accompanied by the accumulation of icaritin-type aglycones, particularly icaritin and desmethylicaritin. An icaritin-imprinted MMIP was synthesized and systematically characterized, exhibiting high binding capacity (58.14 mg g⁻¹), favorable adsorption kinetics, and selective recognition toward target aglycones. Under optimized conditions, the MMIP enabled controlled depletion of icaritin from fermented matrices, and residual levels were accurately quantified by a validated HPLC-UV method, achieving a removal efficiency of 84.5 %. Selective removal of aglycones resulted in a pronounced attenuation of cartilage-promoting effects in zebrafish models, and the magnitude of functional loss was quantitatively correlated with the degree of depletion, providing direct evidence of metabolite-activity causality. Compared with conventional fractionation approaches, the proposed strategy enables selective chromatographic modulation of target analytes with minimal disturbance to the surrounding chemical matrix, extending chromatographic analysis from passive profiling to active molecular intervention and providing a generalizable framework for causality-oriented metabolite identification in complex systems.
Workflow for characterizing volatile oxidation compounds in walnut oil by headspace solid-phase microextraction comprehensive two-dimensional gas chromatography time of flight mass spectrometry coupled with tile-based Fisher ratio analysis and other chemometric tools.
Padilla CM, Synovec RE
J Chromatogr A · 2026 Aug · PMID 42177852 · Publisher ↗
Due to their high fat content, it is well known that walnuts are highly susceptible to oxidation and thermal degradation. These processes produce various compounds, including aromatics, aldehydes, acids, ketones, and alc...
Due to their high fat content, it is well known that walnuts are highly susceptible to oxidation and thermal degradation. These processes produce various compounds, including aromatics, aldehydes, acids, ketones, and alcohols, resulting in poor quality walnuts and shorter shelf life. The goal of this work was to demonstrate a high-level analytical workflow to follow and capture the kinetic volatile fingerprint of oxidized walnut oil through development of a method using headspace solid-phase microextraction sampling followed by comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (HS-SPME GC × GC-TOFMS) coupled with chemometric data analysis. Starting with freshly cold-pressed walnut oil, vials of the walnut oil underwent accelerated oxidation at 60 °C across a span of 6 weeks. Once HS-SPME GC × GC-TOFMS data was collected for each week of oxidation, tile-based Fisher ratio analysis and ANOVA were utilized to discover 59 class-distinguishing analytes across the 6-week experiment. Density-based spatial clustering of applications with noise visualized with principal component analysis revealed three clear kinetic profile class trends within the 59 analytes, aptly named: diminishing analytes, emerging analytes, and intermediate analytes. A very minor fourth category was also observed - unique analytes - consisting of kinetic trends dissimilar from the other three trends. Of the analytes discovered, previously unreported native compounds were discovered as part of the overall volatile chemical fingerprint of the walnut oil, providing fundamental metabolic insight to the oxidative and thermal degradation processes and their influencing factors. To illuminate the significance of these results, a partial least squares regression model to predict hexanal formation - a known oxidation product - was utilized to identify analyte responses correlated to oxidation across all kinetic profiles. Overall, the analytical workflow demonstrated herein confidently studied the walnut oil oxidation process by coupling high-resolution volatile chemical fingerprints of the walnut oil samples - captured via HS-SPME GC × GC-TOFMS analysis - with rigorous chemometric data analysis, ultimately providing a powerful approach for food science studies.
Construction of hierarchically porous ZnO@ZIF-8 for enrichment and sensitive detection of bisphenols in environmental matrices.
Liu Z, Li D, Ren M … +4 more , Wang Y, Ma W, Zhang N, Lu M
J Chromatogr A · 2026 Aug · PMID 42177851 · Publisher ↗
Due to their environmental durability and potential for bioaccumulation, bisphenol compounds result in serious threats to biological systems and human well-being, necessitating the development of extremely effective anal...
Due to their environmental durability and potential for bioaccumulation, bisphenol compounds result in serious threats to biological systems and human well-being, necessitating the development of extremely effective analytical techniques for trace-level monitoring. In this work, a sacrificial-template strategy was employed, in which ZnO served as both the structural scaffold and precursor to direct the controlled growth of ZIF-8, resulting in a hierarchical micro-mesoporous ZnO@ZIF-8 composite. This architecture effectively mitigated the mass-transfer limitations commonly associated with conventional microporous metal-organic framework materials. When employed as a dispersive solid-phase extraction adsorbent, the composite reached adsorption equilibrium rapidly within 3 min, offered ultralow detection limits (0.03-0.1 ng mL), and showed high adsorption capacities of 381-408 mg g⁻¹. These characteristics confirm its strong potential for the highly sensitive analysis of bisphenol pollutants in intricate environmental matrices.
A synchronous counter-positive strategy via online CE-SELEX for high-efficiency aptamer selection.
Zhao Y, Li L, Zhao L … +2 more , Zhu C, Qu F
J Chromatogr A · 2026 Aug · PMID 42176419 · Publisher ↗
Capillary electrophoresis-based systematic evolution of ligands by exponential enrichment (CE-SELEX) has been widely recognized as an effective method for aptamer selection. In this study, we developed a CE-SELEX strateg...
Capillary electrophoresis-based systematic evolution of ligands by exponential enrichment (CE-SELEX) has been widely recognized as an effective method for aptamer selection. In this study, we developed a CE-SELEX strategy to synchronize the counter and positive selection in a single online CE operation, involving the successive injections of the ssDNA library and two proteins as well as their online-modular reaction based on their differentiated electrophoretic mobilities, herein called online synchronous counter-positive CE-SELEX (oscpCE-SELEX). Two model proteins, human lactoferrin (HLF) and ferritin (Fer), were selected. Fer, as the counter protein, first passed through the ssDNA library zone and bound a portion of oligonucleotide sequences, after which HLF was introduced to perform positive selection. Through three rounds of oscpCE-SELEX and sequence analysis, Seq.H-2 was identified with a stem-loop structure and three motifs, exhibiting the highest affinity of 0.39 ± 0.02 μmol/L. Besides, the binding analysis showed that Seq.H-2 exhibited excellent specificity against Fer and other interfering proteins. Furthermore, the versatility of oscpCE-SELEX was confirmed by performing several groups of proteins, and its feasibility for the synchronous selection of two protein aptamers was also evaluated. With the advantages of being fast, efficient, and controllable, oscpCE-SELEX helps address the challenge of separating positive and counter selection in traditional offline SELEX and shows potential for efficient aptamer selection.
A dividing-plane interpretation of thermodynamic void volume in reversed-phase liquid chromatography from PS-DVB and C8/C18 comparisons.
Tsui HW, Huang YJ, Hu JB … +1 more , Tsai MF
J Chromatogr A · 2026 Aug · PMID 42173052 · Publisher ↗
Accurate adsorption isotherms in liquid chromatography require an operational definition of the mobile-stationary phase boundary, which is commonly embedded in the hold-up (void) volume. In the minor-disturbance method (...
Accurate adsorption isotherms in liquid chromatography require an operational definition of the mobile-stationary phase boundary, which is commonly embedded in the hold-up (void) volume. In the minor-disturbance method (MDM), the corresponding thermodynamic void volume V is often interpreted as a substitute for the true liquid volume; however, in reversed-phase systems V can depend on the probe adsorbate, implying an underlying reference-state ambiguity. Here we investigate the physical meaning of V in reversed-phase liquid chromatography by applying MDM to methanol (MeOH), acetonitrile (MeCN), and acetone (ACE) on a highly cross-linked polymeric poly(styrene-divinylbenzene) (PS-DVB) phase and a hybrid-silica C18 phase, and by comparing these results with previously reported data on a silica-based C8 phase. MDM migration data were reconstructed using shape-preserving PCHIP interpolation and integrated to obtain V and surface-excess isotherms. The hybrid C18 phase yielded an essentially adsorbate-independent V (1.088-1.094 mL), whereas PS-DVB exhibited a modest but systematic increase in the order MeOH < MeCN < ACE (1.231-1.247 mL); the silica C8 phase showed larger adsorbate-to-adsorbate variation even after length normalization. Neither PS-DVB nor hybrid C18 exhibited an apparent negative surface-excess region over the explored concentration range, consistent with an interfacial concentration profile that places the effective liquid-solid boundary close to the solid surface under neat-adsorbate conditions. To parameterize thermodynamic descriptors, we further fitted the raw MDM migration data using a self-consistent total-uptake convention by treating the reference hold-up volume V as an adjustable parameter and adopting a finite-layer BET model. MeOH and MeCN were described up to 70 vol.% for all phases, whereas ACE could be represented only at low concentration. The first-layer affinity parameter K provided the most robust cross-column metric, yielding similar values for silica C8 and hybrid C18 but substantially larger values for PS-DVB. The corresponding apparent first-layer adsorption free energy showed a steeper dependence on the equivalent molecular diameter for PS-DVB than for C8/C18, consistent with the stronger enhancement of neat-water retention on PS-DVB. Overall, the results demonstrate that V in reversed-phase systems is a dividing-plane-dependent thermodynamic reference that reflects stationary-phase microstructure and neat-adsorbate accessibility rather than a universal measure of the true void volume, and provide a practical basis for consistent excess-to-total isotherm interpretation across materially distinct reversed-phase stationary phases.
Dynamic model-based control for process variations in ion-exchange chromatography.
Mao RQ, Chen YC, Liao YX … +3 more , Yang YX, Yao SJ, Lin DQ
J Chromatogr A · 2026 Aug · PMID 42166806 · Publisher ↗
The capability of smart manufacturing to enable predictive and autonomous decision-making under uncertainty is highly valuable to ion-exchange chromatography (IEC), a critical purification step that is sensitive to varia...
The capability of smart manufacturing to enable predictive and autonomous decision-making under uncertainty is highly valuable to ion-exchange chromatography (IEC), a critical purification step that is sensitive to variations in sample composition and loading density. However, conventional IEC operation relies on predefined elution conditions, including fixed elution gradient and collection window, which limits its adaptability to process variations. To address this limitation, a model-based control system was developed for the dynamic and autonomous optimization of IEC under process variations. The system incorporated the mechanistic models that combined equilibrium dispersive model and steric mass action model to quantitatively predict protein elution behavior. By integrating communication technologies, the model predictions were used to automatically determine and implement the optimal elution gradient and collection window, enabling model-based decision-making. The experimental validation demonstrated that the model-based control system consistently achieved purity above 96.0% and yield exceeding 88.0%. These results indicate that both product quality and process performance could be maintained despite process variability. Overall, the proposed model-based control system enabled the dynamic and simultaneous adjustment of elution gradient and collection window, transforming IEC operation from predefined conditions to a predictive and adaptive control approach, thereby enhancing process robustness and operational flexibility.
Effect of modification of silica surface on the extent of enantiomer self-disproportionation.
Gumieniak J, Kautz SA, Olbrycht M … +2 more , Korbetskyy M, Antos D
J Chromatogr A · 2026 Aug · PMID 42166805 · Publisher ↗
The interplay between the extent of the phenomenon of self-disproportionation of enantiomers (SDE) and the functionalization of the silica surface was investigated. The elution pattern of individual enantiomers in nonrac...
The interplay between the extent of the phenomenon of self-disproportionation of enantiomers (SDE) and the functionalization of the silica surface was investigated. The elution pattern of individual enantiomers in nonracemic mixtures of citalopram, methyl N-acetyl-phenylalaninate, metalaxyl, methyl p-tolyl sulfoxide, and Binol was analyzed for the adsorbents containing unmodified silica (Si), amino-functionalized silica (NH2) and diol-functionalized silica (Diol). The highest yield for the more abundant enantiomer, which was the separation target, was achieved for the Si adsorbent; it decreased in the sequence: Si, NH2, and Diol. Only for Binol, the separation yields achieved for the Si and NH2 adsorbents were comparable, yet with a very low binding capacity of the former. A mechanistic model was used to quantify the adsorption behavior in each chromatographic system and determine the constants of homo and hetero associations on the adsorbed surface. The results obtained indicated preferable formation of hetero-associates over homo-associates, which underlaid the separation selectivity. This preference diminished with increasing hydrophobicity of the adsorbent surface, with the exception of the most hydrophobic Binol, for which the SDE effect was the most pronounced in the NH2 column. This implies the possibility of adjustment of the silica surface functionality to improve the performance of the SDE-driven separation.
Simultaneous determination of acylcarnitines, fatty acids, and amino acids by 3-nitrophenylhydrazine derivatization and ultra-high performance liquid chromatography/tandem mass spectrometry.
Ardalani H, Dannarm SR, Spégel P
J Chromatogr A · 2026 Aug · PMID 42166804 · Publisher ↗
Acylcarnitines (ACs) play a pivotal role in metabolism, most notably by facilitating the transport of fatty acids (FAs) into mitochondria for β-oxidation, a key step in cellular energy production. Dysregulation of AC, FA...
Acylcarnitines (ACs) play a pivotal role in metabolism, most notably by facilitating the transport of fatty acids (FAs) into mitochondria for β-oxidation, a key step in cellular energy production. Dysregulation of AC, FA, and amino acid (AA) levels has been linked to various metabolic disorders, including cardiovascular diseases, neurodegenerative conditions, and cancer. Consequently, monitoring these metabolites in blood samples provides valuable insights into metabolic health and disease progression. In this study, we developed a method for the quantification of carnitine, seven ACs, fifteen FAs, and thirteen AAs in human serum using reversed-phase ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). By employing 3-nitrophenylhydrazine (3-NPH) derivatization, we achieved high detectability for ACs, with limits of detection (LODs) ranging from 0.01-0.27 ng/mL for ACs, 0.22-1.76 ng/mL for FAs and 0.17-18.25 ng/mL for AAs. Recovery rates ranged from 92-126% for ACs, 56-116% for FAs and 86-115% for AAs. Inter- and intra-day precision were below 20% for all metabolites except two FAs. This method provides a reliable and sensitive tool for the simultaneous analysis of ACs, FAs, and AAs in serum, with potential applications in clinical diagnostics and metabolic research.
Tracking of volatile organic compound emissions from unsaturated polyester resin-based artificial stone using automated static headspace-gas chromatography-mass spectrometry.
Chen Q, Wang H, Chen X … +3 more , Liang J, Lan H, Wang L
J Chromatogr A · 2026 Aug · PMID 42166803 · Publisher ↗
To enable rapid and reliable tracking of volatile organic compounds (VOCs) emitted from unsaturated polyester resin (UPR)based artificial stone, an automated static headspace gas chromatography-mass spectrometry (SHS-GC-...
To enable rapid and reliable tracking of volatile organic compounds (VOCs) emitted from unsaturated polyester resin (UPR)based artificial stone, an automated static headspace gas chromatography-mass spectrometry (SHS-GC-MS) method was developed and systematically optimized. Key parameters, including incubation temperature (60°C), incubation time (30 min), and inlet temperature (250°C), were optimized to achieve efficient extraction and separation of seven target VOCs: dichloromethane, methyl acetate, ethyl acetate, ethylbenzene, styrene, benzaldehyde, and styrene oxide. The method demonstrated excellent linearity (R² = 0.991-0.998), low limits of detection (0.18-0.36 µg g) and quantification (0.54-1.11 µg g), along with satisfactory accuracy (recoveries of 88.3-104.6%) and precision (RSD < 12.2%). Uncertainty analysis revealed that calibration and standard preparation were the dominant contributors to overall measurement uncertainty. Application of the method to UPR-based artificial stone during curing showed a pronounced time-dependent decline in VOC emissions. Styrene was the dominant component, peaking at 953 µg g in the early curing stage and decreasing to baseline levels after approximately 29 days. Dichloromethane and ethyl acetate declined to near detection limits within 8 days, ethylbenzene persisted for about 13 days, while methyl acetate and benzaldehyde remained detectable for up to 24 days. These results indicate that the early curing stage poses the highest emission risk. Overall, the proposed method provides a robust analytical tool for VOC tracking, supporting emission control and environmental risk assessment of UPR-based artificial stone.
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