基于金属有机框架水凝胶的一步式快速富集检测养殖水体中孔雀石绿北大核心CSCD

孔雀石绿是一种三苯甲烷类化合物,在水产品饲养中对疾病的防治有着不错的疗效,但因对人体健康有危害而被列为禁用药。由于实际样品中成分复杂,对于此类染料的检测方法难以同时兼具富集性好、灵敏度高且方便快速的优点。该工作制备了金属有机框架材料(MOF),采用MOF纳米材料掺杂的水凝胶(PAAM-SA/MOF)对养殖水体中的孔雀石绿进行吸附研究。采用一系列表征手段对MOF、PAAM-SA和PAAM-SA/MOF的微观形貌进行分析,结果表明吸附材料已成功合成。通过优化水凝胶吸附剂用量、吸附时间、孔雀石绿溶液pH、吸附温度、孔雀石绿溶液初始浓度等吸附萃取条件,使溶液中的孔雀石绿基本完全吸附在水凝胶中,在最优条件下,吸附效率最高可达97%。此外,采用不同极性的有机溶剂对吸附的孔雀石绿进行洗脱,通过优化洗脱液体积,脱附率最高达99%。在最佳条件下,该方法在高、中、低3个水平下的样品加标回收试验中回收率达到84.8%~118.1%,相对标准偏差小于5.1%,方法的检出限为0.083μg/L(S/N=3),定量限为0.25μg/L(S/N=10)。该方法简化了前处理过程,结合了MOF和水凝胶这二者各自的优点,添加的MOF材料可以在水凝胶体系中发挥其良好的吸附性,既解决了传统的MOF材料因粒径太小而回收率低的难题,便于吸附后直接提取,同时也解决了纯水凝胶吸附效率较低的问题,整体上提高了吸附效率和可回收性。实际样品测试表明该新型水凝胶吸附材料可用于养殖水体中孔雀石绿的快速萃取和检测,在食品检测领域具有很大潜力。

One-step rapid enrichment and detection of malachite green in aquaculture water based on metal-organic framework hydrogel

Malachite green is a triphenylmethane compound, which has a good effect on disease prevention and control in the breeding of aquatic products, but it is a prohibited drug because it is detrimental to human health. Owing to the low content of target malachite green and complex components in the actual sample, simultaneously achieving good enrichment, high sensitivity, convenience, and rapidity detecting is difficult. Metal-organic framework (MOF) has a multidimensional network structure, good stability, and large specific surface area, and has broad application prospects in adsorption. However, the small particle size of MOF materials and the difficulty of recycling hinder their development. The hydrogel has a three-dimensional network structure that can encapsulate the MOF nanomaterials in the network, enhancing adsorption performance and facilitating separation from the adsorbed solution. In this study, MOF materials were prepared, and hydrogel doped with MOF nanomaterials (polyacrylamide-sodium alginate/metal-organic framework, PAAM-SA/MOF) was used to investigate the adsorption of malachite green in aquaculture water. The transmission electron microscopy was used to characterize MOF nanomaterials, scanning electron microscopy was used to examine the morphology and structure of the hydrogels before and after adsorption of malachite green, representing the successful synthesis of adsorbent materials with excellent properties. The mechanical properties of the hydrogels were investigated using a tensile testing machine, with a maximum tensile strain of up to 300%, without breaking and failing to remove when separated from the solution to be tested. The pore size of PAAM-SA/MOF hydrogel is considerably smaller than that of PAAM-SA, which is beneficial to increase the specific surface area of the adsorbent and thus improve the adsorption performance.
A series of optimizations were performed on the adsorption conditions of the hydrogel adsorbent and the optimized conditions were obtained as follows: the amount of adsorbent used was 0.1 g, adsorption time was 5 h, the pH of malachite green solution was 9, the adsorption temperature was 40 ℃, and the initial concentration of malachite green solution was 100 mg/L. Under these conditions the adsorption efficiency could reach up to 97%. Furthermore, the adsorbed malachite green was eluted with organic solvents of various polarities, and the highest desorption efficiency was achieved when acetonitrile with higher polarity was used as the eluent. Simultaneously, the eluent volume was optimized, with 2 mL acetonitrile added to the malachite green-enriched hydrogel adsorbent to achieve the highest desorption efficiency of 99%. The enriched sample was separated using a Dionex Bonded Silica Products C₁₈ column (50 mm×2.1 mm, 3 μm), and eluted with an ammonium acetate-acetonitrile solvent system. The results showed that the limit of detection (LOD, S/N=3) was 0.083 μg/L, the limit of quantification (LOQ, S/N=10) was 0.25 μg/L, and the spiked recoveries of malachite green at high, medium, and low levels were 84.8%-118.1% with the relative standard deviations less than 5.1%. The pretreatment is simplified using this approach and combines the respective advantages of MOF and hydrogel to enable one-step enrichment of malachite green in aquaculture water. The additional MOF material can exert good adsorption in the hydrogel system, which solves the problem of low recovery of traditional MOF materials caused by tiny particle size, facilitating direct extraction after adsorption, and also solves the problem of low adsorption efficiency of pure hydrogel, improving the overall adsorption efficiency and recyclability. The actual sample test shows that the new hydrogel adsorption material can be used to extract and detect trace malachite green in aquaculture water. It is a novel, fast and convenient pretreatment approach with great potential in food detection.