Journal of separation science最新文献

Chiral covalent organic frameworks (CCOFs) are emerging porous materials with tunable chiral structures, abundant pores, and high surface areas, gaining significant attentions in separation, sensing, and asymmetric catalysis. This review summarizes the synthesis methods of CCOFs and their applications in chiral recognition. It discusses the advantages and limitations of three synthesis strategies, including chiral post-modification, direct synthesis, and chiral-induced synthesis. The review also highlights the potential of CCOFs in chiral separation, sensing, and asymmetric catalysis for efficient purification, detection, and synthesis of chiral molecules. Challenges and future directions for the preparation and application of CCOFs are also addressed, aiming to guide further research and practical applications.

Cembranoids are significant flavor precursors found in flue-cured tobacco leaves. The degradation products can serve as important aromatic compounds. In this study, 16 cembranoids were discovered in flue-cured tobacco leaves by liquid chromatography–mass spectrometry (MS), and 1 cembranoid featuring both oxidation and dehydrogenation from α/β-cembranoid was identified for the first time. α- and β-cembranoids were confirmed to be precursors to various degradation products. Additionally, β-cembranoid was prone to epimerize into α-cembranoid while simultaneously undergoing allylic rearrangement, with the hydroxyl group undergoing migration. During the aging and curing processes, cembranoids can easily add oxygen atoms to the carbon–carbon double bonds, whereas the hydroxyl group in the structure may form epoxides, oxidize into ketones, or undergo dehydration reactions. Additionally, the microwave plasma torch interfaced with an MS was used to create and detect the pyrolysis and oxidized products of cembranoids. More degradation products were discovered, including oxidation products with the addition of one to three oxygen atoms, as well as a series of aromatic compounds such as 1,3,5-heptatriene and its range of homologs. This research presented the different degradation pathways of cembranoids in flue-cured tobacco during aging and curing processes, offering valuable insights for the enhancement of tobacco production techniques and quality control.

Cembranoids are significant flavor precursors found in flue-cured tobacco leaves. The degradation products can serve as important aromatic compounds. In this study, 16 cembranoids were discovered in flue-cured tobacco leaves by liquid chromatography–mass spectrometry (MS), and 1 cembranoid featuring both oxidation and dehydrogenation from α/β-cembranoid was identified for the first time. α- and β-cembranoids were confirmed to be precursors to various degradation products. Additionally, β-cembranoid was prone to epimerize into α-cembranoid while simultaneously undergoing allylic rearrangement, with the hydroxyl group undergoing migration. During the aging and curing processes, cembranoids can easily add oxygen atoms to the carbon–carbon double bonds, whereas the hydroxyl group in the structure may form epoxides, oxidize into ketones, or undergo dehydration reactions. Additionally, the microwave plasma torch interfaced with an MS was used to create and detect the pyrolysis and oxidized products of cembranoids. More degradation products were discovered, including oxidation products with the addition of one to three oxygen atoms, as well as a series of aromatic compounds such as 1,3,5-heptatriene and its range of homologs. This research presented the different degradation pathways of cembranoids in flue-cured tobacco during aging and curing processes, offering valuable insights for the enhancement of tobacco production techniques and quality control.

Chiral covalent organic frameworks (CCOFs) are emerging porous materials with tunable chiral structures, abundant pores, and high surface areas, gaining significant attentions in separation, sensing, and asymmetric catalysis. This review summarizes the synthesis methods of CCOFs and their applications in chiral recognition. It discusses the advantages and limitations of three synthesis strategies, including chiral post-modification, direct synthesis, and chiral-induced synthesis. The review also highlights the potential of CCOFs in chiral separation, sensing, and asymmetric catalysis for efficient purification, detection, and synthesis of chiral molecules. Challenges and future directions for the preparation and application of CCOFs are also addressed, aiming to guide further research and practical applications.

The aim of this research was the therapeutic drug monitoring for valproic acid in epilepsy patient's serum samples by the common, sensitive, and accessible HPLC-UV method. Because of the absence of a suitable chromophore in the valproic acid structure, a facile, selective, and cost-effective pre-column derivatization was designed. This catalyst-free ultrasound-assisted derivatization assay can accomplish the derivatization very quickly only in 5.0 min and at a mild temperature of 60°C. 2,4ʹ-Dibromoacetophenone and nonanoic acid was used as derivatizing agent and internal standard, respectively. The effect of sample pH, buffer concentration, ultrasound exposure time, reaction temperature, and derivatizing agent amount were optimized. The proposed method exhibited a good linear range of 5.0–300.0 µg/mL with acceptable correlation coefficients of 0.9981. The limit of detection was as low as 0.4 µg/mL. Also, the limit of quantification was reported as 1.3 µg/mL. Interday and intraday relative standard deviations (n = 10) were 1.1% and 0.3%–7.0%, respectively. In addition, the relative recovery ranged from 100.3% to 107.7%. The measurement of valproic acid was performed in the presence of several epilepsy and non-epilepsy drugs by the developed protocol. This confirmed the specific and accurate determination of valproic acid in the patient's serum. A comparative evaluation was employed against the precise chemiluminescence immunoassay approach. The correlation coefficient between the two methods was 0.9992, which demonstrated the results were statistically the same.

The aim of this research was the therapeutic drug monitoring for valproic acid in epilepsy patient's serum samples by the common, sensitive, and accessible HPLC-UV method. Because of the absence of a suitable chromophore in the valproic acid structure, a facile, selective, and cost-effective pre-column derivatization was designed. This catalyst-free ultrasound-assisted derivatization assay can accomplish the derivatization very quickly only in 5.0 min and at a mild temperature of 60°C. 2,4ʹ-Dibromoacetophenone and nonanoic acid was used as derivatizing agent and internal standard, respectively. The effect of sample pH, buffer concentration, ultrasound exposure time, reaction temperature, and derivatizing agent amount were optimized. The proposed method exhibited a good linear range of 5.0–300.0 µg/mL with acceptable correlation coefficients of 0.9981. The limit of detection was as low as 0.4 µg/mL. Also, the limit of quantification was reported as 1.3 µg/mL. Interday and intraday relative standard deviations (n = 10) were 1.1% and 0.3%–7.0%, respectively. In addition, the relative recovery ranged from 100.3% to 107.7%. The measurement of valproic acid was performed in the presence of several epilepsy and non-epilepsy drugs by the developed protocol. This confirmed the specific and accurate determination of valproic acid in the patient's serum. A comparative evaluation was employed against the precise chemiluminescence immunoassay approach. The correlation coefficient between the two methods was 0.9992, which demonstrated the results were statistically the same.

The widespread use of organophosphorus pesticides (OPs) has raised significant environmental and health concerns due to their residues in soil and potential entry into the food chain. This study introduced chiral analysis methods for four OPs—methamidophos (METHP), dipterex (DIP), malathion (MALA), and isothiophos-methyl (ISOME)—using liquid chromatography–tandem mass spectrometry (LC–MS/MS) with cellulose-based chiral columns. Three distinct methods were established: one for METHP, another for DIP, and a third for MALA and ISOME. Key chromatographic variables, including organic mobile phases and column temperatures, were systematically optimized, achieving maximum resolutions (Rs) of 1.61 for METHP, 2.40 for DIP, 1.70 for MALA, and 2.02 for ISOME. The QuEChERS method was employed for sample pretreatment, ensuring high recoveries. All three methods demonstrated excellent linearity (R > 0.998), accuracy with recoveries ranging from 79% to 121%, precision with RSD% < 11%, and sensitivity with low limits of enantiomer detection (LODs) as low as 0.17 µg/kg for METHP, 0.087 µg/kg for DIP, 0.062 µg/kg for MALA, and 0.054 µg/kg for ISOME, representing a sensitivity improvement of 16–172 times compared to existing methods. Field soil samples from Yangzizhou District, Nanchang, China, revealed significant contamination by ISOME, with concentrations of a single enantiomer reaching up to 8343 µg/kg, while MALA exhibited varying enantiomeric ratios with depth. This study provides robust analytical tools for monitoring chiral OP residues in soil, contributing to food safety and environmental protection.