Abstract:

A series of fragment imprinted polymers for selective recognition of seven triazole pesticides(triadimefon, diniconazole, paclobutrazol, uniconazole, tebuconazole, triadimenol and bitertanol) were prepared through fragment imprinting technique, utilizing various benzene derivatives as the alternative-template. Results of batch binding experiments show that the fragment imprinted polymer(M1) with 2-nitrophenol as the template exhibit the highest recognition ability for the tiazoles. In light of the effects of the structures of the triazoles on the adsorption capacity of the fragment imprinted polymer, the recognition mechanism is proposed as follows: the terminal phenyl group of the tiazoles enters a cavity in the fragment imprinted polymer, while the tiazoles′ hydroxyl standing outside the cavity forms hydrogen bond between with the nitrogen atom of the functional monomer 4-vinylpyridine standing outside the cavity; the former is the key factor affecting the recognition of the fragment imprinted polymer. Finally, the polymer(M1) was used as the sorbent of solid-phase extraction. For the molecularly imprinted solid-phase extraction(MISPE) procedure, the loading, washing and elution conditions were optimized. The optimized MISPE procedure was applied to the clean-up of the matrix solid-phase dispersion(MSPD) extracts from soil samples for the determination of the above-mentioned triazole pesticides. The clean-up of MISPE was proved. Recoveries of MSPD-MISPE extracts from soil samples spiked at three levels were 75%—102%, with good precision(RSD=3%—9%, n=5). The lowest limits of detection(the ratio of signal to noise=3) ranged from 0.9—15 μg/kg. This study highlights the potential of the novel method combining the simplicity of MSPD with the high selectivity of MISPE for extraction of trace compounds from complex matrices.

Key words: Fragment imprinting; Triazole pesticide; Recognition mechanism; Molecularly imprinted solid-phase extraction; Matrix solid-phase dispersion