Molecularly imprinted polymers combined with membrane-protected solid-phase extraction to detect triazines in tea samples

Spherical molecularly imprinted polymers (MIPs) were prepared by emulsion polymerization. The isothermal adsorption and selective adsorption indicated that the MIPs obtained exhibit excellent specific recognition for the template (atrazine) and its analogues. The MIPs were encapsulated in a polypropylene microporous membrane to fabricate MIP adsorption packages for the direct extraction of triazines in uncentrifuged and unfiltered tea extracts. The extraction conditions affecting the extraction efficiency, including the type and volume of extraction solvent, the number of MIP adsorption packages, the surface area of the MIP adsorption packages, the mass of MIPs in the MIP adsorption packages, the extraction time, the eluting solvent, and the eluting volume, were optimized. Under the optimal extraction and high-performance liquid chromatography–tandem mass spectrometry conditions, the method exhibited excellent linearity in the range from 0.5 to 250 ng g^-1, with R² ≥ 0.9992. The detection limit of the method was 0.09–0.18 ng g^-1. The intraday and interday relative standard deviations ranged from 3.1% to 7.5% and from 3.1% to 7.9%, respectively. The method was successfully used to detect triazines in five tea samples. At a spiking concentration of 2 ng g^-1, satisfactory recoveries ranging from (81 ± 3)% to (104 ± 7)% were obtained. The membrane-protected solid-phase extraction method based on molecularly imprinted material is expected to be widely used to enrich triazines in complex samples. [Figure not available: see fulltext.].