Hong Zhikai, Dong Yingjiao, Wang Ruijie, Chen Yao, Wang Guanhua
College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, PR China.
College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, PR China.
J Chromatogr A. 2022 Aug 16;1678:463357. doi: 10.1016/j.chroma.2022.463357. Epub 2022 Jul 20.
TAPT-AN-COF, an imine-based covalent organic framework, was synthesized by a solvothermal method of 2,4,6-trihydroxy-benzene-1,3,5-tricarbaldehyde (TP) and 4,4',4″-(1,3,5-Triazine-2,4,6-triyl)trianiline (TAPT). The structure was characterized and tested by several techniques, revealing that the material had good stability and high specific surface area. The adsorption experiment demonstrates that the adsorption isotherm of TAPT-AN-COF followed the Freundlich isothermal equation, while its adsorption kinetics conformed to the pseudo second-order kinetic model. After characterization, the prepared TAPT-AN-COF was used to separate and enrich nitroimidazoles (NDZs) in milk and meat as the solid-phase extraction (SPE) adsorbent. The effects of adsorbent dosage, pH value, washing solvent, elution solvent type and volume on recoveries were studied. Under the optimal conditions, a method for the determination of NDZs in milk and meat samples was established based on high performance liquid chromatography-ultraviolet detection(HPLC-UVD).The result showed that NDZs had good linearity in the concentration range of 25-500 µg·kg, and the determination coefficients (r) were all above 0.99. When spiked at 25, 50 and 125 µg·kg, the recoveries of three kinds of food samples ranged from 64.5% to 85.3%, the limits of detection (LODs) were between 2 and 10 µg·kg, and the relative standard deviations were all below 15.9%. In addition, the recoveries of NDZs didn't decrease significantly after being reused for 6 times, showing that TAPT-AN-COF has excellent reusability. Compared with HLB and MCX sorbents, TAPT-AN-COF had better extraction efficiency and qualified purification efficiency. The established method had a satisfying performance on the determination of NDZs in food samples.
TAPT-AN-COF是一种基于亚胺的共价有机框架材料，通过2,4,6-三羟基苯-1,3,5-三甲醛（TP）和4,4',4″-(1,3,5-三嗪-2,4,6-三基)三苯胺（TAPT）的溶剂热法合成。通过多种技术对其结构进行了表征和测试，结果表明该材料具有良好的稳定性和高比表面积。吸附实验表明，TAPT-AN-COF的吸附等温线符合Freundlich等温方程，其吸附动力学符合准二级动力学模型。经过表征后，将制备的TAPT-AN-COF作为固相萃取（SPE）吸附剂用于牛奶和肉类中硝基咪唑类（NDZs）的分离和富集。研究了吸附剂用量、pH值、洗涤溶剂、洗脱溶剂类型和体积对回收率的影响。在最佳条件下，建立了基于高效液相色谱-紫外检测（HPLC-UVD）的牛奶和肉类样品中NDZs的测定方法。结果表明，NDZs在25-500 μg·kg浓度范围内具有良好的线性，测定系数（r）均大于0.99。当加标浓度为25、50和125 μg·kg时，三种食品样品的回收率在64.5%至85.3%之间，检测限（LOD）在2至10 μg·kg之间，相对标准偏差均低于15.9%。此外，NDZs重复使用6次后回收率没有显著下降，表明TAPT-AN-COF具有优异的可重复使用性。与HLB和MCX吸附剂相比，TAPT-AN-COF具有更好的萃取效率和合格的净化效率。所建立的方法在食品样品中NDZs的测定方面具有令人满意的性能。
