Off-line magnetic Fe(3)O(4)@SiO(2)@MIPs-based solid phase dispersion extraction coupling with HPLC for the simultaneous determination of olaquindox and its metabolite in fish muscle and milk samples

An innovative core–shell magnetic molecularly imprinted polymers, Fe(3)O(4)@SiO(2)@MIPs, was elaborately tailored for specific separation and enrichment of olaquindox (OLA) and its metabolic marker methyl-3-quinoxaline-2carboxylic acid (MQCA). Herein, benefiting from the combination of functionalized magnetic nanoparticles (Fe(3)O(4)@SiO(2)) and MIPs, Fe(3)O(4)@SiO(2)@MIPs not only possessed favorable magnetic properties and stability, avoiding tedious sample pretreatment process, but also demonstrated exceptional selective recognition ability and adsorption capacity, suppressing influence of coexisting interfering substances. Encouraged by prominent merits, Fe(3)O(4)@SiO(2)@MIPs-based magnetic solid phase extraction with HPLC method was developed, realizing simultaneous measurement of OLA and MQCA. Under optimal conditions, excellent linear ranges of 0–100 μg/L with detection limit of 0.175–0.271 μg/L were obtained. The proposed method was finally utilized for determination of OLA and MQCA in fish muscle and milk samples with satisfactory recoveries (80.56–95.26%) and relative standard deviation below 8.1%, furnishing a reliable and sensitive strategy for enrichment and detection residual veterinary drugs in food samples.