| A novel molecularly imprinted polymer has been prepared using silica gel as support material, enrofloxacin as template, 3-aminopropyltriethoxysilane (APTES) as functional monomer, tetraethoxysilicane (TEOS) as cross-linker by combining surface molecular imprinting technique with a sol-gel process. The imprinted polymer was evaluated by FT-IR and static and kinetic adsorption experiments. The results showed that the imprinted sorbent exhibited good recognition, selective ability and offered a faster kinetics for the adsorption and desorption of the template enrofloxacin. The results of the Scatchard model evaluation indicated that the adsorption isotherm of imprinted polymer towards the template molecule were in good accordance and with linearity. The saturated adsorption capacity (Qmax) of imprinted sorbent toward enrofloxacin was 3.33 mg g-1.A method was developed with this polymer as enrichment sorbent for on-line solid-phase extraction coupled with high performance liquid chromatography to detect trace enrofloxacin in animal-derived products. The parameters affecting the procedure including the sample pH, loading flow rate and time, the eluting time were optimized in this research. With a loading flow rate of 1.0 ml min-1 for sampling 50 ml of 0.1μg L-1 enrofloxacin-H3PO4 (pH=2.5), the enrichment factor has achieved 566. The detection limit (S/N=3) was 0.008μg L-1. The peak area precision (RSD, %) for nine replicate detections of 0.1μg L-1 enrofloxacin was 4.39% and the linear range (r2=0.9952) was 0.04-20μg L-1.To evaluate the usefulness of the novel imprinted sorbent, the fresh samples of fish and chicken from local market, determined to be free of enrofloxacin, were spiked with three levels of enrofloxacin (10 ng g-1, 20 ng g-1 and 30 ng g-1) and analyzed after simple pretreatment under optimal experimental conditions. At each concentration, good recoveries of fish and chicken muscle have ranged from 70.27% to 81.16 %, respectively. It is proved that the detection of enrofloxacin in animal-derived products is feasible in this method. |
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