AFG-2

Aflatoxins (AFs) such as AFB₁, AFB₂, AFG₁, and AFG₂ are some of the main sources of exogenous contamination in traditional Chinese medicines (TCMs). Contamination by these four AFs can occur in the process of planting, processing, production, storage, and circulation, and will affect the safety of TCM applications. In this work, we synthesized a macroporous covalent organic framework (COF) as the adsorbent for the online solid-phase extraction (SPE) of the four AFs. Monodisperse polystyrene microspheres were used as the sacrificial template for the creation of macropores. The physical properties of macroporous COF were characterized. The online SPE processes were optimized. The online SPE method coupled with a high-performance liquid chromatograph equipped with a UV detector was used to determine the amount of the four AFs in TCM samples, including lotus seed, Sterculia lychnophora, coix seed, Ziziphi spinosae semen, and malt. Using the optimized method, a linear calibration curve was obtained in the range of 0.05-100 ng/g. The limits of detection were 0.015-0.03 ng/g. The recoveries of the four AFs in TCM samples ranged from 80.0 % to 101 %. This study presents a feasible and effective approach for the detection of AFs at trace level.

MIPs have great potential for the selective adsorption of aflatoxins, due to their tailored binding sites. However, their synthesis using aflatoxins as templates is potentially hazardous and expensive. A viable solution to this challenge is to use dummy templates instead. Several dummy templates have been investigated for the synthesis of MIPs for aflatoxins. However, these studies have been conducted under varying conditions and by different research groups, resulting in a lack of systematic comparison. This makes it difficult to identify the optimal dummy template. In this study, five dummy templates and two functional monomers were evaluated to synthesize highly selective MIPs for aflatoxins. The polymers were produced through precipitation polymerization. FTIR, TGA, and SEM were employed to evaluate the structure, stability, and morphology of the material. The adsorption ability of the MIP and NIP was analyzed using LC-MS/MS. The findings revealed that MIPs synthesized using DMC exhibited the highest binding efficiency. In addition, MIPs created with functional monomers methacrylic acid (MAA) and methacrylamide (MAM) demonstrated similar adsorption abilities for aflatoxins. The adsorption process of the MIP is best described by the pseudo-second-order kinetic model and the Langmuir isotherm. The maximum monolayer adsorption capacities were measured at 8.13, 7.50, 8.38, and 7.63 mg/g for AFB₁, AFB₂, AFG₁, and AFG₂, respectively.