Molecularly imprinted polymer as a novel solid-phase microextraction coating for the selective enrichment of trace imidazolinones in rice, peanut, and soil.

The development and application of an imazethapyr molecularly imprinted polymer-based solid-phase microextraction coating were investigated. A novel molecularly imprinted polymer coating with imazethapyr as template was firstly prepared by a one-step in situ polymerization method, and demonstrated specific selectivity to imidazolinone herbicides in complicated samples. The structural characteristics and extraction performance of the imazethapyr molecularly imprinted polymer coating were studied. The molecularly imprinted polymer coating was homogeneous, dense, and heat and solvent resistant. Adsorption capacity experiments showed that the molecularly imprinted polymer coating could selectively extract imazethapyr and its structural analogs, and the maximum adsorption capacity was 2.5 times as much as that of the nonimprinted polymer coating. A method for the determination of five imidazolinones by imazethapyr molecularly imprinted polymer solid-phase microextraction coupled with high-performance liquid chromatography was developed. The linear range was 0.50-50 μg/L for imazameth, imazamox, imazapyr acid, and imazethapyr, and 1.0-100 μg/L for imazaquin acid, and the detection limits were within the range of 0.070-0.29 μg/L. The method was applied to simultaneous and multiresidual determinations of trace imidazolinones in rice, peanut, and soil samples with satisfactory recoveries of 60.6-99.5, 79.1-123, and 61.3-116%, respectively, and relative standard deviations of 0.40-10%, which indicated that this method was suitable for the trace analysis of imidazolinones in complex food and environmental samples.