A novel method to prepare monolithic molecular imprinted polymer fiber for solid-phase microextraction by microwave irradiation

In this paper, a new approach to prepare monolithic molecularly imprinted polymer (MIP) fibers for solid-phase microextraction is proposed with the help of microwave irradiation. Imprinting polymerization was carried out within silica capillaries in 4.5 min, using dimethyl phthalate (DMP) as a template molecular, -methacrylic acid as a functional monomer and ethylene dimethacrylate as a crosslinker, acetonitrile as the porogenic solvent. The synthesis was optimized by varying the ratio of template/monomer and different volume of porogen. The resulted MIP fibers were obtained after silica being etched away with a controlled length of 1 cm, and subsequently characterized by SEM. In order to increase the selective extraction of DMP, factors affecting the extraction including extraction time, salt concentration, desorption time, and desorption solvents were investigated for solid-phase microextraction procedures in detail. The selectivity coefficients, defined as the extraction amount ratio of MIP to its nonimprinting fiber, were 5.6, 2.6, and 1.4 for DMP and its counterpart including dibutyl phthalate and di-n-octylo-phthalate, respectively. The resulted fibers were also applied to detect DMP, dibutyl phthalate, and di-n-octylo-phthalate in bottled beverage samples coupled to HPLC and resulted in relative recoveries of up to 73.8-98.5%, respectively.