Sensitive determination of phenylurea herbicides in soybean milk and tomato samples by a novel hypercrosslinked...

A heterocyclic hypercrosslinked polymer (Py-DMB HCP) was prepared by Friedel-Crafts alkylation reaction using pyrrole as monomer and p-dimethoxybenzene as crosslinker. The Py-DMB HCP was employed as an adsorbent for solid-phase extraction (SPE) of phenylurea herbicides (PUHs) and showed superior extraction performance. Thus, a sensitive analytical method for the determination of PUHs from soybean milk and tomato samples was established by combining Py-DMB HCP based SPE with high performance liquid chromatography. Under the optimal conditions, good sensitivity was achieved with the detection limits of 0.10-0.20 ng mL^-1 and 0.06-0.15 ng g^-1 for soybean milk and tomato samples, respectively. The linearity range of PUHs was 0.3-150.0 ng mL^-1 and 0.2-150.0 ng g^-1, respectively. The recoveries were 87.4% to 116% with relative standard deviations lower than 6.5%. Density functional theory calculation was performed to study the intermolecular interaction mechanism, demonstrating the coexistence of both the H-bonding and π-π interactions in the adsorption process.