Determination of Triazine Residues in Fruits and Vegetables by Dual-Template Molecularly Imprinted Solid Phase Extraction Combined with High Performance Liquid Chromatography

A new dual-template molecularly imprinted polymer (MIPs) for efficient adsorption of triazines was prepared with cyromazine and melamine as template molecules, and its adsorption performance was evaluated for triazine residues in fruits and vegetables. Under the optimized condition of molar ratio of cyromazine to melamine = 3:2, the highest adsorption capacity of MIPs was achieved. The maximum adsorption capacity of MIPs at two specific binding sites 2.85 and 5.46 mg/g, and the binding constants were 26.688 and 80.775 mg/L, respectively. The adsorption process attained equilibrium in 100 minutes and showed a higher adsorption capacity than did non-imprinted polymers (NIPs). Molecular imprinting-based solid-phase extraction (MI-SPE) combined with high performance liquid chromatography (HPLC) was used for the measurement of four triazine residues including atrazine, prometryn, ametryn, and simetryn in cucumber, apple, and corn. The limit of detection of this method was 0.01–0.03 ng/mL, and the average recoveries of spiked samples at concentrations ranging from 0.1 to 0.5 μg/mL were 83.2%–102.3% (n = 3), with relative standard deviation (RSD) between 2.3% and 6.8%. The proposed method, therefore, is suitable for the trace detection of triazine residues in fruit and vegetable samples.