Controllable synthesis of uniform flower-shaped covalent organic framework microspheres as absorbent for solid-phase extraction of trace 2,4-dichlorophenol.

Controllable synthesis of micro-flower covalent organic frameworks (MFCOFs) with controllable size, monodisperse, spherical, and beautiful flower shape was realized by using 2,5-diformylfuran (DFF) and p-phenylenediamine (p-PDA) as building blocks at room temperature. High-quality MFCOFs (5 - 7 µm) were synthesized by controlling the kind of solvent, amounts of monomers, catalyst content, and reaction time. The synthesized MFCOFs possessed uniform mesopores deriving from the intrinsic pores of frameworks and wide-distributed pores belonging to the gap between the petals. The MFCOFs-packed solid-phase extraction (SPE) column shows adsorption capacity of about 8.85 mg g-1 for 2,4-dichlorophenol (2,4-DCP). The MFCOF-based SPE combined with the HPLC method was established for the determination of 2,4-DCP in environmental water. The linear range of this method is 20-1000 ng mL-1 (R2 > 0.9994), and limit of detection (S/N = 3) is 10.9 ng mL-1. Spiked recoveries were 94.3-98.5% with relative standard deviations lower than 2.3%.

NH2-MIL-53(Al) Polymer Monolithic Column for In-Tube Solid-Phase Microextraction Combined with UHPLC-MS/MS for Detection of Trace Sulfonamides in Food Samples.

In this study, a novel monolithic capillary column based on a NH2-MIL-53(Al) metal-organic framework (MOF) incorporated in poly (3-acrylamidophenylboronic acid/methacrylic acid-co-ethylene glycol dimethacrylate) (poly (AAPBA/MAA-co-EGDMA)) was prepared using an in situ polymerization method. The characteristics of the MOF-polymer monolithic column were investigated by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffractometry, Brunauer-Emmett-Teller analysis, and thermogravimetric analysis. The prepared MOF-polymer monolithic column showed good permeability, high extraction efficiency, chemical stability, and good reproducibility. The MOF-polymer monolithic column was used for in-tube solid-phase microextraction (SPME) to efficiently adsorb trace sulfonamides from food samples. A novel method combining MOF-polymer-monolithic-column-based SPME with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was successfully developed. The linear range was from 0.015 to 25.0 µg/L, with low limits of detection of 1.3-4.7 ng/L and relative standard deviations (RSDs) of < 6.1%. Eight trace sulfonamides in fish and chicken samples were determined, with recoveries of the eight analytes ranging from 85.7% to 113% and acceptable RSDs of < 7.3%. These results demonstrate that the novel MOF-polymer-monolithic-column-based SPME coupled with UHPLC-MS/MS is a highly sensitive, practical, and convenient method for monitoring trace sulfonamides in food samples previously extracted with an adequate solvent.

Synthesis of the alkylated active metabolite of tipidogrel.

Tipidogrel (3), an effective anti-platelet drug candidate working by irreversibly inhibiting P2Y12 receptor, holds great promise in overcoming clopidogrel resistance and increasing bioavailability. As a prodrug like other thienopyridines, it metabolizes through thiophene ring opening to form active metabolites 3a and 3b, nevertheless they are easily to form disulfide bond. Derivatization of 3a and 3b via alkylation with MPBr can prevent disulfide conjugation and ensure reliable pharmacokinetic results. Thus, in order to support its pre-clinical studies on efficiencies in the formation of tipidogrel active metabolites, 13a and 13b were synthesized via seven steps of chemosynthesis and incubation with MPBr in rat plasma in vitro. The resulting crude productions were purified by semi-preparative HPLC to give Z configuration 13a and E configuration 13b. In LC-MS/MS spectra, they showed identical fragmentation pattern and retention time with M-13a and M-13b, the MPBr-derivatives of active metabolites of tipidogrel in rats. Thus, 13a and 13b were the anticipated alkylated active metabolite of tipidogrel. In addition, in the nucleophilic substitution of thioacetate with compound 11, besides the anticipated compounds 12a and 12b, their isomers compounds 12c and 12d were detected, whose structures were confirmed and the corresponding mechanism was presented.

[Phenolic constituents of Ampelopsis grossedentata from zhangjiajie].

OBJECTIVE: To study the phenolic constituents from Ampelopsis grossedentata. METHODS: Compounds were isolated using column chromatographic techniques (silica gel, polyamide gel, Sephadex LH-20) and semi-preparative HPLC. Structures were elucidated on the basis of spectral data (NMR and HR-MS). RESULTS: Eight compounds were isolated and identified as ampelopsin (I), 5, 7, 3',4',5'-pentahydroxyflavanone (II), galloyl-beta-D-glucopyranoside (III), gallic acid (IV), ethyl gallate (V), myricitrin (VI), (2R, 3S)-5,7,3',4',5'-pentahydroxyflavanonol (VII) and myricetin (VIII). CONCLUSION: Compounds II and VII are obtained from this genus for the first time.

[Content determination of two isomers containd in Garcinia hanburyi by HPLC].

OBJECTIVE: To establish a method for determing the content of two isomers containd in Garcinia hanburyi by HPLC. METHOD: Chromatographic column of SunFire (Waters) C8 (2.1 mm x 150 mm, 3.5 microm) was adopted, with acetonitrile-methanol-0.3% trifluoroacetic acid (36: 37:27) as the mobile phase. The detection wavelength was 360 nm,the flow rate was 0.3 mL x min(-1), and the column temperature was 28 degrees C. RESULT: The linear regression equation of r-gambogic acid was Y = 2.87 x 10(6) X - 2.24 x 10(5), r = 0.999 9. The linear regression equation of S-gambogic acid was Y = 3.31 x 10(6) X - 1.44 x 10(5), r = 0.999 9. The average recoveries were 100.0% and 100.9%, with RSD being 2.1% and 2.5% (n = 6), respectivley. The average contents of two gambogic acid in G. hanburyi were 30.06% and 21.45%, respectively. CONCLUSION: The method was so convenient and stable that it can be used for identification and content determination of two isomers containd in G. hanburyi.

[Determination of the total content of astragaloside IV in Radix Astragali].

OBJECTIVE: To determine the total content of astragaloside IV in Radix Astragali. METHODS: The measurement conditions were used as follows: Irregular C18 (4.6 mm x 250 mm, 5 microm) column; mobile phase: acetonitrile-water (32:68); flow rate: 1.0 ml/min; detector: ELSD 2000; the temperature of drift tube: 100 degrees C; gas flow: 2.7 L/min. RESULTS: Eight batches of Radix Astragali from different sources were determined. The stability, precision and reproducibility of the method were studied, RSD <3%. CONCLUSION: There is great difference between the content of astragaloside IV in Radix Astragali by different processing methods.