色谱最新文献

With the growing global popularity of traditional medicine and natural drugs， especially in Southeast Asia， the quality of traditional Chinese medicines （TCMs） has attracted the attention of regulators. China's major TCM export destinations， such as South Korea， Japan， and Europe， have formulated strict maximum residue limits （MRLs） of pesticides in TCMs. Therefore， a sensitive and high-throughput method for the simultaneous determination of 101 pesticide residues in Platycodonis radix and extracts of Angelica sinensis was established， involving gel permeation chromatography （GPC） coupled with gas chromatography-ion trap mass spectrometry （GC-ITMS）. In this method， the samples were first ground into fine powder and extracted twice with 20 mL acetonitrile in an ultrasonic cleaner for 30 min. After centrifugation for 10 min at 6000 r/min， the supernatants were combined and dried at 40 ℃ using a rotary vacuum evaporator. The residue was re-dissolved in 2 mL ethyl acetate-cyclohexane （1∶1， v/v） and purified by gel permeation chromatography using a 40 cm×20 mm column. The eluent collecting time was optimized as 17-30 min to ensure both the recovery of target compounds and the removal of interferences such as pigments and lipids from the target compounds. The eluent was then dried and re-dissolved with 1 mL toluene for analysis. The 101 pesticide residues were separated using the DB-5MS capillary column and analyzed by ion trap mass spectrometry. The pretreatment conditions and ion trap mass spectrometry parameters were optimized to effectively reduce the interference of complex TCM matrices and greatly improve the quantitative accuracy of the analysis and recovery of the target pesticides. Three spiked levels of 101 pesticides were tested. The average recovery range was 58.3%-108.9% and the relative standard deviations （RSDs） at the three spiked levels （n=10） ranged from 0.4% to 16.5%. The limits of detection （LODs， S/N=3） of the 101 pesticide compounds ranged from 0.2 to 40.0 μg/kg， while the limits of quantification （LOQs， S/N=10） ranged from 0.6 to 120.0 μg/kg， which met the maximum residue limits of China's main TCM export countries and organizations. This rapid analysis method was easy to operate and high throughput， with strong sensitivity and good repeatability. The employment of gel permeation chromatography overcame the drawback of inadequate cleanup of the solid phase extraction column during TCM analysis. The application of ion trap technology further eliminated the interference of matrix impurities and increased the accuracy of the quantitative and qualitative analyses. This method fills the knowledge gap in multiple pesticide residue determination in TCMs using gas chromatography-ion trap mass spectrometry and is a useful and beneficial alternative to current analytical methods of TCMs.

Covalent organic frameworks （COFs） are an emerging class of porous crystalline materials composed of multidentate organic units connected by covalent bonds. COFs have been demonstrated to exhibit great potential and research value in many fields， including gas storage and separation， photoelectric devices， fluorescence sensors， catalysis， drug delivery， dye and pollutant adsorption， and electronic devices， and so on. The COFs obtained by post-synthesis modification tend to exhibit high crystallinities and porosities， thereby rendering them suitable materials for use in the fields of chiral resolution， asymmetric catalysis， and chromatography. In this work， TpPa-NO₂ was synthesized from 1，3，5-tricarbaldehyde phloroglucinol and 2-nitro-1，4-phenylenediamine， which was then reduced to TpPa-NH₂. Subsequently， this material was modified with D-glucose via a post-synthesis modification strategy to obtain the TpPa-NH₂-Glu. TpPa-NH₂-Glu were characterized by nuclear magnetic resonance （NMR） spectroscopy， Fourier transform-infrared （FT-IR） spectroscopy， X-ray powder diffraction （XRD） analysis， etc. In the XRD pattern， the peaks observed at 4.7°， 8.1°， 11.1°， and 27° were attributed to the TpPa-NH₂-Glu， and these peaks are consistent with previous reports， thereby confirming the successful synthesis of this derivative. In addition， circular dichroism experiments indicated that the TpPa-NH₂-Glu exhibited a Cotton effect， further confirming the chiral COF was prepared. Subsequently， this material was immobilized on the surface of spherical silica gel particles via the net-wrapping method to prepare a stationary phase for high performance liquid chromatographic column. Using n-hexane-isopropanol （9∶1， v/v） or methanol-water （9∶1， v/v） as mobile phases at a flow rate of 0.5 mL/min， 16 racemates and two benzene-based positional isomers （o，m，p-nitroaniline and o，m，p-Iodoaniline） were successfully resolved by this chiral column. In addition， under methanol-water （9∶1， v/v） mobile phase conditions， five racemates were separated， among which propranolol hydrochloride， warfarin， and metoprolol reached baseline separation. Furthermore， under n-hexane-isopropanol （9∶1， v/v） mobile phase conditions， 11 racemates were resolved， among which ethyl 2-bromopropionate and 3-butyn-2-ol reached baseline separation. Meanwhile， the effect of temperature on the TpPa-NH₂-Glu liquid chromatography column and the repeatability of the TpPa-NH₂-Glu liquid chromatography column were also explored. The HPLC column prepared by TpPa-NH₂-Glu had good repeatability， and its relative standard deviation （RSD） was 1.55% and 1.46%， respectively. It is demonstrated that the TpPa-NH₂-Glu material has good resolution ability for chiral compounds.

Capillary electrophoresis-mass spectrometry （CE-MS） combines the advantages of capillary electrophoresis， such as the high separation efficiency and low sample consumption， and the high detection sensitivity of mass spectrometry and the ability for providing the structural information for structure elucidation of unknown components. However， the interface technology for coupling capillary electrophoresis and mass spectrometry is still not well resolved. In the present work， we explored the application of the sheathless CE-MS interface which was prepared by gold foil-wrapped CE separation column tip directly as a spray electrode for the analysis of five tyrosine kinase inhibitors， namely sunitinib， imatinib mesylate， gefitinib， dasatinib and erlotinib. This interface integrates separation and electrospray ionization in one capillary， which is easy to manufacture， low in cost， and can be produced in batches. We found that using the nonaqueous CE separation mode can not only achieve baseline separation of five tyrosine kinase inhibitors， but also obtain stable mass spectrometry signals. First， we investigated the effect of the electrolyte solution composition on the separation. The optimized background electrolyte composition was obtained： 2% （v/v） acetic acid and 5 mmol/L ammonium acetate in acetonitrile-methanol （80∶20， v/v）. Under optimized conditions， the five kinase inhibitors could be baseline separated， meantime， the sheathless interface could also maintain stable electrospray for a long time. The relative standard deviation （RSD） values of the intraday and interday repeatability of the analyte retention times were less than 0.5% and 0.8%， respectively， and the RSD value between interface batches is less than 2.6%. Compared with CE-MS with aqueous phase， the separation column efficiency of the five tyrosine kinase inhibitors under nonaqueous phase conditions is higher， the detection sensitivity is higher， and the absolute detection limit reaches amol level. In addition， we evaluated the sheathless interface with various organic acids， such as palaflin A， salvianolic acid C， and rosmarinic acid， as well as hydrophobic macrolide antibiotics， azithromycin， erythromycin， and sporin A， good separation effect and mass spectrometric detection results can be obtained.

Heparin （Hp） is the most widely used anticoagulant drug in the clinics， with an annual global output of over 10 billion dollars. Hp， a member of the glycosaminoglycans （GAGs）， is prepared from porcine intestinal mucosa via extraction， separation， and purification. Hp is a linear polysaccharide with repeating disaccharide units. Low-molecular-weight heparins （LMWHs） are depolymerized from Hp via chemical or enzymatic degradation. Compared with Hp， LMWHs exhibit less bleeding side effect， milder immunogenicity， and higher bioavailability when injected subcutaneously. In general， Hps， including LMWHs， are high complex drugs with large molecular weights （MWs）， inhomogeneous MW distributions， and structural heterogeneity， including different degrees and locations of sulfonation， and unique residues generated from different production processes. Thus， developing efficient analytical methods to elucidate the structures of Hps and characterize or quantitate their properties is extremely challenging. Unfortunately， this problem limits their quality control， production optimization， clinical safety monitoring， and new applications. Research has constantly sought to elucidate the complicated structures of Hp drugs. Among the structural analysis and quality control methods of Hp currently available， chromatographic methods are the most widely studied and used. However， no literature thoroughly summarizes the specific applications of chromatographic methods in the structural analysis， manufacturing process， and quality control of Hp drugs. This paper systematically organizes and describes recent research progresses of the chromatographic methods used to analyze Hp drugs， including the identification and composition of monosaccharides， disaccharides， oligosaccharides， and polysaccharides. The applications， innovations， and limitations of these chromatographic methods are also summarized in this review. The insights obtained in this study will help production and quality control personnel， as well as drug researchers， obtain a deeper understanding of the complex structures of Hp drugs. This paper also provides a comprehensive reference for the structural analysis and quality control of Hps， proposes ideas for the development of new quality control methods， and lays a strong foundation for the in-depth structural elucidation of Hp drugs.