Dummy Template–Based Molecularly Imprinted Solid-Phase Microextraction Coating for Analysis of Plasticizers in Food Samples

Dummy molecularly imprinted polymers (DMIPs) were grafted on the surface of microspheres (CG161M) by surface imprinting and layer by layer self-assembling process and applied as adsorbent for the rapid and selective detection of phthalate compounds, such as diethyl phthalate (DEP), dibutyl phthalate (DBP) and dioctyl phthalate (DOP). Dioctyl phthalate (DOP) was chosen as a dummy template for diethyl phthalate (DEP) and dibutyl phthalate (DEP), allowing selective and specific identification of DEP and DBP and did not affect the accuracy of the analysis even if the template has not been eluted completely. The synthesized composites were characterized by Fourier transform infrared spectrometer, scanning electron microscope, static/kinetic adsorption, thermogravimetric analysis and nitrogen adsorption analysis. The maximum adsorption capacities of the MIPs for DEP, DBP and DOP were 0.006, 0.008 and 0.007 mg g −1 , respectively. The adsorption of phthalates reached equilibrium within 260 min and complied well with pseudo-second-order kinetic model and Langmuir model. Moreover, MIPs-based sorbents combined with hollow fibre stirring bar sorptive extraction followed by gas chromatography–mass spectrometry was applied to the recognition of DEP, DBP and DOP in several food samples. Under the optimum conditions, the limits of detection (LODs) for DEP, DBP and DOP were 0.0047, 0.0054 and 0.0031 mg L −1 , with spiked recoveries of 73.06–106.02% and relative standard deviations (RSDs) within 3.91–6.89%, exhibiting high adsorption capacity and good selectivity of DMIPs towards DEP, DBP and DOP. Since the template of surface molecularly imprinted polymers could be changed with the analytes, MIP-based molecularly imprinted polymers combining with hollow fibre stirring bar sorptive extraction can be a promising and selective method for recognition and separation of a certain series of analytes with similar skeleton in complicated samples without sample clean-up. Graphical Abstract