Preparation and selective recognition of a novel solid‐phase microextraction fiber combined with molecularly imprinted polymers for the extraction of parabens in soy sample

A prepared molecularly imprinted polymer with ethyl p‐hydroxybenzoate as template molecule was applied for the first time to a homemade solid‐phase microextraction fiber. The molecularly imprinted polymer‐coated solid‐phase microextraction fiber was characterized by scanning electron microscopy and thermogravimetric analysis. Various parameters were investigated, including extraction temperature, extraction time, and desorption time. Under the optimum extraction conditions, the molecularly imprinted polymer‐coated solid‐phase microextraction fiber exhibited higher selectivity with greater extraction capacity toward parabens compared with the nonimprinted polymer‐coated solid‐phase microextraction fiber and commercial fibers. The molecularly imprinted polymer‐coated solid‐phase microextraction fiber was tested using gas chromatography to determine parabens, including methyl p‐hydroxybenzoate, ethyl p‐hydroxybenzoate, and propyl p‐hydroxybenzoate. The linear ranges were 0.01–10 μg/mL with a correlation coefficient above 0.9943. The detection limits (under signal‐to‐noise ratio of 3) were below 0.30 μg/L. The fiber was successfully applied to the simultaneous analysis of three parabens in spiked soy samples with satisfactory recoveries of 95.48, 97.86, and 92.17%, respectively. The relative standard deviations (n=6) were within 2.83–3.91%. The proposed molecularly imprinted polymer‐coated solid‐phase microextraction method is suitable for selective extraction and determination of trace parabens in food samples.