Journal of Chromatography A最新文献

In recent years, machine learning has been increasingly applied across various scientific fields, including microfluidics. This study presents a fully automated workflow for the optimization of the geometry of periodic microfluidic systems for chromatography. In particular, Bayesian optimization is combined with Computational Fluid Dynamics to compute the permeability and axial liquid dispersion in perfectly ordered micropillar array beds designed for liquid chromatography, within a fully automated closed-loop iterative optimization toward the best-performing structure. To achieve a sufficiently rapid computation of the data points, the Two-Zone Moment Analysis, which reduces the computational effort for the axial dispersion to a steady-state computation on a single unit cell, was used. During the optimization, the performance of the pillar array geometries was evaluated by calculating their minimal chromatographic separation impedance E_min, which merges the demands for both a low dispersion and a high permeability. Restricting ourselves to the case where the external porosity is kept constant at ε=50%, it has been found that, compared to the most commonly used pillar array arrangement reported in the literature (lattice angle α=60^∘, circular pillars), E_min can be reduced by 25% by adjusting the lattice angle to 70^∘ for circular pillars and that E_min can even be reduced by 35% by also allowing for elliptical pillars and adjusting the lattice angle to 50^∘.

Recent studies have shown that essential oils (EOs) from spices are effective in reducing high blood glucose levels, with β-caryophyllene (BCP) emerging as one of the most promising bioactive compounds. Despite the increasing interest in this field, few studies in the literature have elucidated the link between sample components and their resulting biological activities. In this paper, a detailed investigation was carried out, using a black pepper EO as a case study, and α-glucosidase as biological target. Initial biological assays showed very similar activities between the entire EO and the corresponding amount of BCP in the EO on α-glucosidase. These outcomes confirmed the manifest role of BCP, and further suggested that EO's fractionation could help to unravel the complex interactions among terpene families, BCP, and the biological target. As a first step, a suitable preparative GC method was developed to enable the effective and rapid isolation of the separated monoterpene and sesquiterpene families for subsequent biological assays. The biological outcomes bio-guided consequent fractionation procedures, which were aimed at understanding the role of BCP in the overall sesquiterpene family. Consequently, the use of multidimensional preparative GC guaranteed the effective isolation of the sesquiterpene family without BCP, underscoring its relevant role in this fraction. In a complementary approach, the sesquiterpene family was further fractionated to understand potential enhancing/inhibitory effects with BCP. To the best of authors' knowledge, this paper represents the first instance in the literature where preparative gas chromatography has been employed as an analytical approach to carry out a bio-guided fractionation of EOs.

The extraction of DNA from plant tissues is often hindered by the resilient cell wall, which necessitates cumbersome pretreatment steps in conventional methods. Furthermore, existing techniques typically co-extract total DNA without the capability for sequence-specific isolation. To address these limitations, this study developed a novel oligonucleotide-functionalized hydrophobic magnetic ionic liquid (oligo-HMIL). This material integrates high stability, strong magnetic responsiveness, and exceptional hydrophobicity, allowing it to be magnetically manipulated to directly penetrate plant cell walls and membranes for DNA extraction, thereby eliminating the need for a separate lysis step. More significantly, the material enables sequence-specific recognition and selectively isolates the target DNA from complex matrices containing substantial amounts of non-target DNA, proteins, and other interferents. Based on this material, a lysis-free, all-in-one platform for direct and sequence-specific extraction of DNA was established. Under optimized conditions, the method achieved efficient extraction and enrichment of the target DNA from various plant tissues, with an extraction efficiency of 78.25 ± 1.83%. Compared to a commercial kit, the proposed approach increased DNA yield by at least 3-fold while reducing the processing time from 4 h to 30 min and simplifying the workflow. The material can be recycled and reused, and the method demonstrated excellent stability (RSD = %, n = 3) and reproducibility (RSD = 2.34%, n = 3). This work provides a green, rapid, and reusable platform for targeted plant DNA extraction, holding broad application potential in genetic research and biotechnology.

We present an in-depth theoretical study of the band broadening processes originating from the specific shape and intra-particle diffusion characteristics of metal-organic framework (MOF) particles used in high-performance liquid chromatography (HPLC). Studying perfectly ordered packings, the complex nature of the eddy-dispersion process is filtered out, leaving the pure particle contributions. Using a recently developed modification of Brenner's dispersion formalism to make it applicable to chromatographic systems, highly accurate and comprehensive data sets could be produced. The D_part/D_m dependence (D_part: intra-particle diffusion coefficient, D_m: bulk molecular diffusion coefficient) of plate height curves confirmed that the plate height values in the C-term dominated regime obtained with significantly low D_part/D_m (= 0.004), which can be observed in MOF particles, can be up to approx. 50 times higher (at Pe≅ 100 (Pe: dimensionless interstitial velocity)) than those with larger D_part/D_m (= 0.3) which is typically observed in silica particles used in reversed-phase HPLC. Comprehensive investigation employing typical cuboidal MOF particles revealed that high plate heights which can be observed in MOF-based LC column are almost exclusively due to the inherently slow intra-particle diffusion rates, because the other attributes (non-spherical shape, anisotropic intra-particle diffusion) only showed a minor effect on the produced band broadening. In fact, the non-spherical shape is even advantageous when only considering the pure intra-particle contribution to the plate height. Next to the very small pore diameter compared to the molecular size of typical analyte molecules, another main reason for the low intra-particle diffusion in MOF particles is pointed out to be the fact that the diffusion in the perpendicular direction is strongly suppressed compared to the main diffusion direction (channel direction) in MOFs with anisotropic channel structures (e.g., one-dimensional (1D) or pseudo-1D channel). In the presently considered example, where the diffusion in the two perpendicular directions was reduced to 1/4 of the diffusion in the main diffusion direction, this led to an overall suppression of the intra-particle diffusion with a factor of 2.49.

A heat-assisted array gas membrane separation strategy coupled with High-Performance Liquid Chromatography Fluorescence detection was developed for sensitive determination of metformin based on an indirect quantification principle. Metformin was converted in situ under alkaline heating into volatile dimethylamine (DMA), which was selectively transferred through a hydrophobic Polytetrafluoroethylene membrane and trapped in an acidic acceptor solution, followed by pre-column derivatization with dansyl chloride to enable fluorescence detection. Mechanistic investigations confirmed DMA formation and identified additional alkaline degradation products (guanylurea-type intermediate, urea and guanidine) by HILIC and High-Resolution Time-of-Flight Mass Spectrometry, providing the chemical basis for the indirect workflow. Computational fluid dynamics simulations indicated focused headspace flow across the membrane (57.6% of total flow), negligible trans-membrane pressure (<0.5 Pa) and a moderated membrane temperature (∼49 °C) under an 80 °C heat source, rationalizing efficient transfer and reduced secondary volatilization. Key parameters were optimized, including heating time, absorption configuration, derivatization conditions. Under optimized conditions, the method was linear over 20-100 μg/mL (R = 0.9924) with a limit of detectionof 0.002 μg/mL (S/N = 3). Applicability was demonstrated in corn silk tea and sour jujube kernel tea, giving recoveries of 89.2-99.3% at 100 μg/mL and 95.4-102.0% across spiking levels, with no evident chromatographic interferences. The Alkaline Hydrolysis-Array Gas Membrane Separation-HPLC-FL approach integrates conversion, membrane-based separation and fluorescence derivatization, offering an efficient and solvent-minimized option for routine screening of metformin adulteration in complex matrices.

Inspired by their abundant coordination-unsaturated metal sites and hierarchical pore structure, high-entropy metal-organic frameworks (HE-MOFs) were fabricated and firstly applied in solid-phase microextraction (SPME), and exhibited outstanding extraction performance for polychlorinated biphenyls (PCBs) pollutants. The morphology and structure of prepared multi-metal-doped HE-UiO-66 was systematically characterized. The HE-UiO-66 was coated on stainless steel wire as SPME fiber for headspace extraction of PCBs followed by gas chromatography-flame ionization detection (GC-FID). Compared to conventional MOFs-coated fiber, HE-UiO-66-coated fiber demonstrated superior stability and extraction efficiency. The discussed adsorption mechanism involves the multiple interaction through Lewis acid-base coordination, π-π stacking interactions, and rich pore architecture. The optimized method achieved a broad linear range, low detection limits, and outstanding enrichment factors (8411-15,377), surpassing previously reported values. Satisfactory recovery rates (77.8-111.9%) were obtained in environmental samples and food samples. This study pioneers the application of HE-MOFs in sample preparation, providing a highly efficient and sensitive method for PCBs detection in complex matrices.

Systematic characterization of natural product components is essential for product development and quality control. The root (AMR) and leaf (AML) of Astragalus membranaceus (Fisch.) Bge are used in food and health-related products. However, the composition of triterpenoids in AMR and AML has not been completely clarified. This study proposes a strategy that integrates a virtual database with aglycones to systematically identify triterpenoids in AMR and AML. The aglycones, substituents and sugar moieties of triterpenoids were summarized by integrating previously reported triterpenoids to construct a virtual database. Subsequently, the raw data was compared with a virtual database, and false positives were eliminated by detecting aglycones in the MS/MS spectra, thereby screening for potential triterpenoids. A total of 421 potential triterpenoids were identified, of which 158 were from AMR and 283 were from AML. Among these, 319 triterpenoids were considered potential new compounds. In addition, 6 triterpenoids were identified as chemical markers distinguishing AMR from AML. This study systematically characterized the triterpenoids in AMR and AML, enhancing our understanding of triterpenoids in both AMR and AML, and established a foundation for the further development of AMR and AML. Furthermore, this study developed a workflow for in-depth mining of unknown compounds using data independent acquisition mode to systematically characterize natural products.

A green strategy was developed to modify cyclodextrin-based metal-organic frameworks (CD-MOFs) for fabricating magnetic solid-phase extraction (MSPE) adsorbents targeting polycyclic aromatic hydrocarbons (PAHs). β-cyclodextrin-based MOFs (KOH&β-CD) were synthesized and functionalized with four edible organic compounds (ellagic acid, chlorogenic acid, stearic acid, and tyrosine) to concurrently improve aqueous stability and enhance PAHs recognition. The modified MOFs were then covalently grafted onto Fe₃O₄@SiO₂ magnetic cores and silane-capped, yielding four magnetic composites (Fe₃O₄@SiO₂@MOFs-1-4). Comprehensive characterization confirmed successful fabrication. Adsorption evaluation toward six PAHs (anthracene, fluoranthene, pyrene, benz[a]anthracene, benzo[a]pyrene, and benzo[g,h,i]perylene) revealed high affinity, with the ellagic acid-modified composite exhibiting a maximum capacity of 1.99 mg·g^-1 for benzo[g,h,i]perylene. The process followed the Freundlich isotherm and pseudo-second-order kinetic model, indicating multilayer chemisorption. After optimizing MSPE parameters, a method coupling MSPE with HPLC-FLD was established, offering wide linear ranges (1-3500 ng), low detection limits (0.5-5 ng), and satisfactory precision (RSD < 14.1%). When applied to spiked and real food samples (sausage and flour), the method delivered superior recoveries (84.7-116.9%) and better precision compared to the Chinese national standard method (GB 2762-2022), demonstrating its reliability and potential for monitoring trace PAHs in complex food matrices using green food-grade adsorbents.

Quality control of therapeutic oligonucleotides is mainly achieved by Ion-Pair Reversed Phase Liquid Chromatography (IP-RPLC) coupled to Mass Spectrometry and Anion-Exchange Liquid Chromatography. As manufacturing requirements increase during clinical development, so too do the requirements for the separation of impurities from full-length product. Hence, there is a need for a wider range of analytical methods for therapeutic oligonucleotides. Hydrophilic Interaction Liquid Chromatography (HILIC) is emerging as an orthogonal method for oligonucleotide analysis. We present an Ultra-Performance Liquid Chromatography Mass Spectrometry HILIC method with good separation of truncation impurities in modified RNA. We share an example where the method is applied to partly phosphorothioated single strands that are used to form GalNAc-conjugated double stranded siRNA. Truncation impurities arising from incomplete coupling were well separated from their parent FLP, both for incomplete couplings in the sequences as well as in the GalNAc-cluster, which is built up by successive couplings of a brancher and GalNAc phosphoramidite. The results showed both comparability of HILIC with IP-RPLC and orthogonality of HILIC towards IP-RPLC for the separation of GalNAc-cluster-related truncations.