Determination of cyclopiazonic acid in food samples by using molecularly imprinted polymers based on magnetic halloysite nanotubes.

A fast, accurate, and simple method of molecularly imprinted solid-phase extraction from magnetic molecularly imprinted polymers (m-MISPE) has been developed for the determination of cyclopiazonic acid (CPA) in food samples. For the synthesis of the magnetic molecularly imprinted polymers, the core-shell method through microwave irradiation was employed. Firstly, as the core halloysite nanotubes were functionalized with magnetite nanoparticles. Then, the molecular imprinted polymer (MIP) shell was created around the halloysite nanotube cores by microwave induction. In the MIP synthesis for the template molecule, an analogous compound in structure to that of CPA has been used as a surrogate molecule to reduce the costs and toxicity produced by the toxin. Besides, washing and elution m-MISPE steps were optimized to eliminate the interferences. Cross-reactivity of the m-MISPE proposed method has been tested with different mycotoxins to determine the selectivity of the polymer towards CPA (imprinting factor (IF): MIP/NIP_CPA = 3,1; MIP/NIP_ZON = 2,2; MIP/NIP_AOH = 1,7; MIP/NIP_OCRA = 0,8). Finally, the m-MISPE method has been successfully applied to rice flour samples at three different concentration levels, 75, 120, and 200 μg/L, whose recoveries were 83, 97, and 93% and their RDS were 1, 2, and 2, respectively. The detection and quantification limits were 11.1 and 36.5 µg/kg respectively. This procedure is considered an easy and economical analytical way to determine CPA in food in routine laboratories of any food quality and is easy to implement versus the current methods in the determination of this mycotoxin.