Journal of separation science最新文献

Polycyclic aromatic hydrocarbons (PAHs), known for their environmental ubiquity and toxicity even at trace levels, were effectively extracted using a novel tetrafluoroterephthalonitrile-cyclofructan 6 cross-linked polymer (TFN-CF6-CP) coating. This coating was synthesized through in situ cross-linking polymerization of a cross-linking agent with cyclic fructose 6 (CF6) on glass fiber surfaces, subsequently applied in fiber-in-tube solid-phase microextraction (fiber-IT-SPME). The developed method coupled with high-performance liquid chromatography (HPLC) enabled online PAHs analysis. The TFN-CF6-CP demonstrated superior PAHs adsorption capacity, attributable to its distinctive structural characteristics and multiple interaction mechanisms. Under optimized conditions (70 mL extraction volume, 2.5 mL min⁻¹ sampling flow rate, 0% acetonitrile content, and 2.0 min desorption time), the online fiber-IT-SPME-HPLC method achieved remarkable performance metrics: Low detection limits from 0.013 to 0.037 µg L⁻¹, linear ranges of 0.030–10 µg L⁻¹, and enrichment factors between 895 and 1946. The TFN-CF6-CP exhibits remarkable durability and outstanding reproducibility (RSD ≤ 10.8%). As a result, it is highly suitable for the detection of contaminants in water samples. These findings indicate that the functionalized glass fibers exhibit exceptional adsorption properties, demonstrating significant potential for PAHs pretreatment in diverse aqueous environmental samples.

Chiral covalent organic frameworks (CCOFs) show great potential for chromatographic separation, due to their abundant chiral recognition sites and unique structures. A novel CCOF core-shell composite, CCOF-301@SiO₂, was constructed by post-synthesis modification (PSM) and in-situ growth strategies, and the effect of the amount of acetic acid catalyst on the synthesis of CCOF-301@SiO₂ core-shell microspheres was discussed. The prepared CCOF-301@SiO₂ microspheres composite was used as a multifunctional chiral stationary phase (CSP) for HPLC enantiomeric separation under normal-phase (NP) and reversed-phase (RP) modes. The experimental results showed that the CCOF-301@SiO₂ column exhibited excellent separation performance, with 20 chiral compounds being separated in NP mode and 12 chiral compounds in RP mode, including alcohols, esters, ketones, and amines. Compared with the commercially available Chiralpak AD-H column, the CCOF-301@SiO₂ column exhibited good complementarity in enantiomeric separation performance. In addition, the effects of analyte mass, column temperature, and mobile phase composition on the separation were investigated. Good repeatability and stability of the CCOF-301@SiO₂ column for enantioseparation were observed. This study demonstrates that the CCOFs@SiO₂ constructed by PSM and in-situ growth strategies have great potential as an HPLC stationary phase.

Inverse gas chromatography was used to investigate the isomer separation capability and surface properties of Leonurus cardiaca L. leaves and stems. The retention diagrams of the selected solvents were plotted between 303.2 and 328.2 K using the inverse gas chromatography technique. The selectivity coefficients (α) of the structural isomers were determined for L. cardiaca L. biomass under conditions of infinite dilution using the retention diagram. Besides, the surface properties of L. cardiaca L. biomass were investigated using inverse gas chromatography at infinite dilution. The dispersive surface energy of the adsorbent was determined using the Schultz, Dorris–Gray, Donnet–Park, and Hamieh methods. Adsorption enthalpy and Gibbs free energy were calculated using this technique. It was determined that the surface of both L. cardiaca L. leaves () and stems () exhibit acidic characteristics.

In this study, a miniaturized electromembrane-surrounded solid-phase microextraction (EM-SPME) device was integrated into a microfluidic chip. It was employed for the extraction of phenoxyacetic acid herbicides, including 2-methyl-4-chlorophenoxyacetic acid (MCPA) and 2,4-dichlorophenoxyacetic acid (2,4-D), in environmental and food samples. The separation and determination of the analytes was performed by GC-MS. A nanostructured polypyrrole/zirconium-based metal–organic framework/Ti₃C₂T_x titanium carbide (MXene) fiber, synthesized electrochemically, was used as the acceptor adsorbent and also electrode. The simultaneous application of an electric field and nanocomposite-based adsorption enabled efficient preconcentration of the analytes within a compact and low-solvent system. Effective parameters on the extraction of the analytes were investigated and optimized. Under optimized conditions, the developed EM-SPME–GC-MS method exhibited limits of detection of 0.3 µg L⁻¹ for both analytes and linear ranges of 1–1000 µg L⁻¹ for MCPA and 2,4-D (R² ≥ 0.9934). Intraday and interday RSDs% were below 7.6% and 10.2% respectively, demonstrating satisfactory precision. The method was validated through real sample analysis in river water, cucumber, and rice extracts, achieving recoveries from 89% to 119%. The chip consumes 10 µL of 1-octanol as SLM and 250 µL of methanolic tetrabutylammonium bromide for derivatization per analysis (total < 0.26 mL organic solvent), which is markedly lower than conventional liquid–liquid extraction/solid phase extraction workflows.

A comprehensive mass balance approach was developed to quantitatively determine the oxytetracycline-free base in oxytetracycline hydrochloride. The measurement uncertainty of the reference material includes the uncertainty component introduced during the preparation process. The structural analogues of the principal components were quantitatively determined by liquid chromatography (HPLC-DAD), moisture was determined by the Karl Fischer method, nonvolatile impurities were determined by inductively coupled plasma mass spectrometry (ICP-MS), residual solvents were determined by headspace gas chromatography, and the content of chloride ions was determined by ion chromatography. The principal component structural analog impurities were qualitatively analyzed by HPLC-MS, and the structural analogue impurities were quantitatively analyzed by the external standard method. The HPLC-DAD analysis results showed that there were 17 impurities in oxytetracycline hydrochloride. Eleven out of the 17 impurities were successfully identified by HPLC-MS. The results show that the content of structural analog impurities in oxytetracycline hydrochloride is 47.23 mg/g, the content of nonvolatile impurities is 0.18 mg/g, the content of volatile impurities is 0.89 mg/g, the content of chloride ions is 65.16 mg/g, and the water content is 89.90 mg/g. The free base content of oxytetracycline in oxytetracycline hydrochloride was 796.6 mg/g, and the expanded uncertainty was U = 9.4 mg/g (k = 2). The method was verified by quantitative nuclear magnetic resonance (qNMR) spectroscopy. The results showed that the content of free base in oxytetracycline hydrochloride was 788.6 mg/g, and the uncertainty was U = 6.1 mg/g (k = 2). The established mass balance method provides a strong framework for the formulation and certification of oxytetracycline reference standards and offers a reliable alternative to traditional quantitative methods. This study establishes a validated method for the characterization and quantification of oxytetracycline hydrochloride, which has potential applications in the quality control and standardization process of the pharmaceutical industry.

Triazole antifungals are clinically established agents for the prophylaxis and treatment of invasive fungal diseases in patients with hematologic malignancies. To address the requirements of clinical therapeutic drug monitoring, we developed and validated a novel ultra-high-performance liquid chromatography tandem mass spectrometry method for the simultaneous quantification of three triazole antifungals and their metabolites in human plasma: itraconazole (ICZ), hydroxy-itraconazole (ICZ-OH), voriconazole (VCZ), voriconazole N-oxide (VCZ N-oxide), and posaconazole. The five target analytes were successfully separated using a BEH C18 column (2.1 × 50 mm, 1.7 µm) maintained at 40°C, with gradient elution employing mobile phase A (5.0 mM ammonium acetate in water containing 0.1% formic acid) and mobile phase B (100% acetonitrile [ACN]) at a constant flow rate of 0.4 mL/min. A positive ion pattern was chosen for quantification under multiple reaction monitoring. Following the addition of 10 µL of internal standard, 50 µL of plasma underwent protein precipitation with ACN, and the resulting supernatant was diluted for subsequent analysis. Method validation followed Food and Drug Administration guidelines and Chinese Pharmacopoeia regulations, demonstrating acceptable accuracy, precision, matrix effects, recovery, and stability. The calibration curves exhibited excellent linearity over the range of 0.1–10 µg/mL for all five analytes, with correlation coefficients (r²) ≥ 0.9962, while the lower limit of quantification and limit of detection were established at 0.1 and 0.03 µg/mL, respectively. The intra- and inter-day coefficients of variation were below 8.7% at all concentration levels, and the accuracy was 90.0%–113.0%. This methodology was successfully applied for TDM of three triazole antifungals and their metabolites in 150 patients with hematologic malignancies. Therefore, the method demonstrates good analytical performance, establishing its reliability for clinical TDM of triazole antifungals.

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.