Preparation And Application Of A Molecularly Imprinted Material Of Olaquindox’ Residue Marker

Quinoxalines are veterinary antibiotics used in animal for promoting-growth, disease prevention and treatment. Thereinto carbadox and olaquindox obtained the most intensive application and investigation, which methyl-3-quinoxaline-2-carboxylic acid (MQCA) and quinoxaline-2-carboxylic acid (QCA) have been identified as major metabolites and designated residue markers of them, respectively.In this paper, MQCA was synthesized. Then MQCA was used as template, silica gel as support material,3-aminopropyltriethoxysilane (APTES) as functional momomer, and tetraethoxysilicane (TEOS) as cross-linker, combining surface molecular imprinting technique with the sol-gel process, prepared MQCA moleculaly imprinted polymer (MIP) firstly. The MIP was characterized by Fourier transform infrared (FT-IR) and evaluated through static and kinetic adsorption experiments. The results of adsorption experiments indicated that the MIP had good adsorption capacity, fast binding kinetics and high selectivity for MQCA and QCA.A method was developed with MIP as a selective enrichment sorbent in an online solid phase extraction (SPE) coupled with high-performance liquid chromatography (HPLC) to detect QCA and MQCA in food animal tissue. The parameters affecting the procedure including the sample solvent proportion, pH, loading flow rate and the eluting time were optimized. With a loading flow rate of2.0ml min-1for50ml of1.0μg L-1sampling solution (pH=5.0,1%of methanol contents), enrichment factors of1,349and1,046, and limits of detection (S/N=3) of0.8and2.0ng L-1for QCA and MQCA, respectively, were obtained. The peak area precision (RSD,%) for nine replicate detections was less8%and the linear range (r2>0.99) were0.03-40μg L-1and0.04-40μg L-1, respectively.At last, the pork samples from local market, determined to be free of QCA and MQCA by HPLC, were spiked with three levels of QCA and MQCA (2.0ng g-1,4.0ng g-1and8.0ng g-1) and analyzed after simple pretreatment under optimal experimental conditions. The sample preparation protocol was only included one step extraction with acetonitrile after the release of target analytes through acidic hydrolysis without further sample cleanup. With recoveries of pork samples have ranged from67%to80%. It is proved the new MIP-SPE-HPLC method was successfully applied to the quantification of trace QCA and MQCA in pork muscle.