Journal of separation science最新文献

Novel methods were proposed for determining primaquine (PQN) in tablets by multiple-injection capillary zone electrophoresis (MI-CZE) and by short-end injection CZE (SEI-CZE), both with ultraviolet detection. The background electrolyte (BGE), consisting of 20 mmol/L of tris (hydroxymethyl) aminomethane and 30 mmol/L of hydrochloric acid at pH 2.0, was selected considering a comprehensive study involving the effective mobility versus pH curves of the analytes and BGE components. Experimental designs were applied in methods developments, showing the chemometric tool's applicability in achieving suitable electrophoretic conditions. A baseline resolution in the separation of adjacent peak pairs was obtained by injecting a spacer electrolyte for 18 s, with a voltage of + 15 kV, and the sample can be injected six consecutive times in a single run in less than 3 min, in the MI-CZE method. For the SEI-CZE method, the migration time of PQN was 0.6 min, and the method was applied to a demonstrative forced degradation study. Some validation parameters were evaluated for both methods, and all results were satisfactory, indicating that they can be implemented as PQN determination methods in routine quality control analyses.

Yan Huanglian is the whole grass and rhizome of Corydalis saxicola Bunting (CSB) of the Papaveraceae family. CSB has various pharmacological effects and is a promising ethnopharmaceutical. The chromatographic fingerprint of 16 batches of CSB samples was established in this study. Quantitative analysis of multi-components by single marker and the external standard method (ESM) was used to quantitatively assess seven constituents of CSB. Because of its high stability and availability, dehydrocavidine was used as a reference to determine the relative correction factors (RCFs) of columbamine, epiberberine, coptisine hydrochloride, palmatine chloride, berberine hydrochloride, and chelerythrine based on high-performance liquid chromatography. The calculated quantitative analysis of multi-components by single marker values is consistent with those obtained from the ESM, and the repeatability of the RCFs was demonstrated. For the first time, the quantitative analysis of multi-components by the single marker method has been established for the simultaneous determination of seven components, and it is demonstrated to be feasible and accurate for the quality evaluation of CSB combined with chromatographic fingerprint analysis. The combination of these methods could be used as a reference for quality control in Chinese medicine.

A new nanocomposite based on alginate microbeads impregnated with novel strontium–aluminum layered double hydroxide (Sr-Al LDH) incorporated with choline chloride-urea deep eutectic solvent (ChCl-U DES) was introduced. The microbeads and LDH were characterized by adsorption/desorption isotherms, Fourier-transform infrared spectroscopy, SEM, and x-ray diffraction. The adsorbent was employed for determining penicillin G (PENG) using dispersive solid-phase extraction prior to HPLC analysis. The extraction efficiency of the adsorbent, compared with that of unmodified alginate, showed a 2.5-fold increase. Significant parameters, including elution conditions, sorbent composition and mass, adsorption time, and sample pH, were optimized. The LOD was 0.4 µg kg⁻¹, and the linear range was 1.4–500 µg kg⁻¹. The LOQ (1.4 µg kg⁻¹) was lower than the established maximum level for PENG by the European Union (4 µg kg⁻¹). Enrichment factor and synthesis reproducibility were also investigated. The method's accuracy was evaluated through PENG analysis in dairy products and water, with recoveries of 81%–107% (RSDs < 7.6%). The procedure's greenness was assessed using the Analytical Eco-scale and achieved excellent green credentials. To the best of our knowledge, this is the first report on the synthesis and application of a novel alginate composite for the extraction of PENG from dairy and water samples.

Colquhounia root tablets (CRT) and Tripterygium hypoglaucum hutch tablets (THHT), two major Tripterygium hypoglaucum hutch (THH) commercial preparations, have been used to treat chronic kidney diseases or rheumatic diseases. However, there have been no reports on the chemical comparison between CRT and THHT, greatly hindering the understanding of their pharmacological difference as well as their rational application in clinical practice. In the present study, ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry combined with automated data analysis by MS-DIAL software and MS-FLO website was employed to systematically screen and characterize the components in CRT and THHT. Multivariate statistical analysis was used to compare the differences between these two preparations. As a result, up to 92 components were tentatively identified, and 17 of them were characterized for the first time in THH preparations. According to the criteria of variable importance in projection (VIP) >1, p < 0.05, and fold change (FC) > 1.2, 46 components could be screened as major differential chemical components. Among them, phenolic acids, organic acids, amino acids, and diterpenoids were higher in CRT, while the sesquiterpene alkaloids were relatively higher in THHT. This study clarified the chemical material basis and the difference between CRT and THHT, providing a valuable reference for quality control and clinical rational use of THH preparations.

A chiral monolith stationary phase was fabricated by modifying the monolith surface using L-cysteine through a thiol-epoxy click reaction. L-cysteine-bonded polymer monolith was characterized by scanning electron microscopy/energy-dispersive X-ray and attenuated total reflectance Fourier-transformed infrared. The monomer content and modification temperature were carefully optimized to create a polymer monolith with excellent mechanical stability and permeability. Our findings revealed that the column morphology depended significantly on the porogen concentration and modification temperature for its morphology and efficiency. Adequate pores and binding sites were formed with the optimal porogen content, while a higher modification temperature improved the modification yield, enhancing peak shapes and increasing separation efficiency. The column demonstrated its capability for enantioseparation of dansyl glutamic acid, dansyl aspartic acid, dansyl methionine, and dansyl phenylalanine using a 60 mM ammonium acetate buffer solution and acetonitrile in a 20:80 v/v ratio. It maintained good mechanical stability and repeatability with no relative standard deviation exceeding 7%. These results indicated that the L-cysteine-bonded polymer monolith has excellent potential as a chiral stationary phase.

The metabolism research of bioactive phenolic acids  widely found in natural products is of great significance for elucidating pharmacologic mechanisms and screening lead compounds. However, it is time-consuming and vulnerable to interference to conduct the traditional metabolism approach by applying organisms or biomaterials. Herein, a bionic technology was established by combining online electrochemistry-mass spectrometry (EC-MS) with offline electrochemistry-liquid chromatography-mass spectrometry (EC-LC-MS) to investigate the oxidative transformation and metabolic processes of the active phenolic acids (including salvianolic acid A, caffeic acid, 3, 5-O-dicaffeoylquinic acid, ferulic acid, salvianic acid A, and protocatechuic acid). Phase I metabolism of the phenolic acids were simulated by applying a three-electrode controlled potential electrochemical reactor with a boron-doped diamond electrode, with glutathione mixed into the oxidative products simultaneously for obtaining the phase II metabolites. Finally, structural characterization of the simulated metabolites of the phenolic acids was achieved successfully, including hydroxylation, methylation, demethylation, decarboxylation, etc. It was revealed that the simulated metabolism process based on an electrochemical system was effective in yielding a wide variety of metabolites for these compounds, which was also compared with the metabolism results applying rat liver microsomes. Consequently, this bionic technology is expected to be a powerful tool to investigate the material basis for the efficacy of active ingredients of natural products.

Cortisol and testosterone are important biomarkers for diagnosing complex disorders, including polycystic ovary syndrome and Cushing's syndrome, where symptomatology usually overlaps with other prevalent disorders. This work proposes, for the first time, an analytical method based on a switchable hydrophilicity solvent as an extraction phase for the determination of cortisol and testosterone in oral fluid (OF) by high-performance liquid chromatography with diode-array detection. The optimized extraction conditions consisted of 1000 µL of OF, 100 µL of decanoic acid solution (65 mg/mL), 170 µL of Na₂CO₃, 900 µL of H₂SO₄ and 150 µL of acetonitrile for dilution. The method was validated, and coefficients of determination higher than 0.9926, the limit of detection of 4.55 ng/mL and the limit of quantification of 15.00 ng/mL were obtained. Intra-day precision varied from 5.6% to 11.9%, inter-day precision ranged from 6.1% to 13.5%, and relative recoveries ranged from 98.9% to 104.6% for cortisol, and 89.1% to 103.9% for testosterone. This methodology was successfully applied to five OF samples from volunteers. Moreover, the greenness of this methodology was evaluated based on the sample preparation metric of sustainability achieving a global score of 7.37 which can be considered sustainable.

A selective ultra-high performance liquid chromatography tandem mass spectrometry cubed (UHPLC/MS³) assay for simultaneous determination of methotrexate (MTX) and 7-hydroxy-methotrexate (7-OH-MTX) in human plasma was developed and validated. After protein precipitation with methanol, chromatographic separation of MTX, MTX-d₃, and 7-OH-MTX was performed on a Waters AcQuity UPLC-BEH column (2.1 × 50 mm I.D., 1.7 µm) with gradient elution. MRM³ transition was used for the detection of MTX (m/z 455.2→308.0→175.1) and 7-OH-MTX (m/z 471.3→191.0→148.1). The linear range of UHPLC/MS³ assay for the determination of MTX and 7-OH-MTX was 0.5–300 ng/mL (R² ≥ 0.99) and 5–1500 ng/mL (R² ≥ 0.99), respectively. The enhanced selectivity and sensitivity are the novelties of the developed UHPLC/MS³ assay. The analytical method was successfully applied to simultaneous determination of MTX and its major metabolite 7-OH-MTX in real human plasma samples.

In the current study, a new magnetic sorbent (Fe₃O₄@2,6-diamino-4-(3,4-dihydroxyphenyl) pyridine-3,5-dicarbonitrile) was prepared as a new and efficient sorbent to be used in the magnetic solid-phase extraction method to extract tebuconazole and propiconazole as model compounds. In this regard, effective parameters such as pH of the sample solution, desorption volume, ionic strength, extraction time, desorption time, and amount of the magnetic sorbent were optimized using experimental design. In the optimal condition, the linear dynamic ranges for tebuconazole and propiconazole were between 0.5 and 200.0 µg/L. Also, the limits of detection, limits of quantification, and relative standard deviations were 0.21–0.14 µg/L, 0.49–0.45 µg/L, and 1.3%–4.6%, respectively. The estimated enrichment factors for tebuconazole and propiconazole were 22 and 28, respectively. The absolute recovery (AR%) values for tebuconazole and propiconazole were also 67% and 84%, respectively. Finally, the proposed method was used for determination of tebuconazole and propiconazole in cucumber, tomato, orange, and lemon fruits. The obtained result confirmed that the presented method is capable for the analysis of the selected analytes in complicated matrices. In addition, the ARs% were in the range of 67%–84%. The result proved that the presented method can be an alternative to the extraction process of various pesticides.

Glucosinolates, a crucial group of secondary metabolites in Brassica vegetables, present significant chromatographic separation challenges due to their anionic form, structure diversities, and co-existence of other phenolic compounds. This study comparatively investigated the retention and separation of seven glucosinolates using a mixed-mode reversed-phase/weak anion-exchange column and a conventional reversed-phase C18 column. Separation factors for each glucosinolate with its adjacent peaks were over 1.0 on the mixed-mode column, while co-eluting was observed on the C18 column. The effects of mobile phase additives and pH on the separation and retention of glucosinolates were also investigated. Results showed that glucosinolate retention was inversely related to both buffer concentration and pH. The optimized method for the mix-mode column was applied to the complex Brassica vegetable samples. In addition to the 17 well-resolved glucosinolate peaks, 34 peaks for phenolic compounds were identified in broccoli microgreen, suggesting the successful application scenarios for qualitative analysis in comparison with the single mode reverse phase C18 column. This study demonstrates that the mixed-mode reversed-phase/weak anion-exchange column can be used as a promising separation tool for organic anions in a complex sample matrix.