Recently, pharmaceuticals and personal care products in the water environment exhibited potential risks to both human and aquatic organisms. In order to improve the sensitivity and accuracy of pharmaceutical detection, the polyimidazolyl acetate ionic liquid was synthesized by Radziszewski reaction and coated on cellulose filter papers as a thin-film extraction phase for extraction of non-steroidal anti-inflammatory drugs from water. The attenuated total reflection-infrared spectrometry, thermogravimetric analysis, and scanning electron microscope analyses demonstrated that the polyimidazolyl acetate ionic liquid was successfully prepared and attached to the surface of the cellulose filter paper through chemical bonding. The adsorption capacity of the homemade thin-film extraction material for the four non-steroidal anti-inflammatory drugs was greater than 8898 ng/cm2 under the optimum conditions, and the desorption rate was over 90%. Then, a paper-based thin-film extraction phase-high-performance liquid chromatography-tandem mass spectrometry method was established for the extraction of non-steroidal anti-inflammatory drugs in water. This method provided limits of detection and limits of quantification were in the range of 0.02–0.15 and 0.17–0.50 μg/L, respectively. Hence, the obtained thin-film extraction phase showed excellent recovery and reproducibility for the target non-steroidal anti-inflammatory drugs with carboxyl groups from water. 相似文献
We demonstrate here a novel method for the design of liquid crystals (LCs) via the cyclization of mesogens by flexible chains. For two azobenzene-4,4′-dicarboxylate derivatives, the cyclic dimer, cyclic bis(tetraethylene glycol azobenzene-4,4′-dicarboxylate) (CBTAD), shows LC properties with smectic A phase, while its linear counterpart, bis(2-(2′-hydroxyethyloxy)ethyl azobenzene-4,4′-dicarboxylate (BHAD), has no LC phase. The difference is ascribed to the shackling effect from the cyclic topology, which leads to the much smaller entropy change during phase transitions and increases the isotropic temperature greatly for cyclics. In addition, the trans-to-cis isomerization of azobenzene groups under UV-light is also limited in CBTAD. With the reversible isomerization of azobenzene groups, CBTAD showed interesting isothermal phase transition behaviors, where the LC phase disappeared upon photoirradiation of 365 nm UV-light, and recovered when the UV-light was off. Combined with the smectic LC nature, a novel UV-light tuned visible light regulator was designed, by simply placing CBTAD in two glass plates. The scattered phase of smectic LC was utilized as the “OFF” state for light passage, while the UV-light induced isotropic phase was utilized as the “ON” state. The shackling effect outlined here should be applicable for the design of cyclic LC oligomers/polymers with special properties.
The extract of Bidens bipinnata L. exhibited wide spectrum of bioactivities owing to the presence of flavonoids. In this study, a purification process was developed to enrich the flavonoid-rich extract from B. bipinnata L. (BBTF). AB-8 resin was selected for the purification of total flavonoids. Response surface methodology coupled with Box–Behnken design was employed to optimize the purification condition; it was optimized as pH 5.1, volume of ethanol 80 ml, flow rate of ethanol 1.8 bed volume per hour (BV/h) and concentration of ethanol 76.0%. The total flavonoid content of BBTF was 56.48% under the optimal conditions. The identification of flavonoids in BBTF was conducted using UHPLC–ESI-Q-TOF MS. A total of 14 compounds, including 12 flavonoids, were identified in BBTF. Finally, the in vitro antioxidant activities, α-glucosidase and α-amylase inhibitory activities of BBTF were comprehensively analyzed by an analytical hierarchy process. The results indicated that it exhibited higher bioactivities than the crude extract. These findings suggested that the optimized process could significantly enhance the purity of flavonoids and their bioactivities. This study showed a comprehensive analysis of a total flavonoid extract of B. bipinnata L. for the first time, which could provide a useful approach for its purification process and quality control as well as bioactivities. 相似文献