Molecularly Imprinting Materials Solid Phase Co-Extraction—HPLC For Detecting Two Veterinary Drugs Simultaneously

Along with the increase of people on demand of animal food ceaselessly, a large number and a variety of veterinary drugs are used in many links of modern livestock and poultry production. Although veterinary drugs can improve annimal’s living conditions, reduce animal’s morbidity and maortality, part of veterinary drugs also have other functions, such as promote animal growth, improve animal production performance, lower feed conversion rate, improve the quality of animal products and so on. But the use of veterinary drugs, also pollutes the environment, results in the emergence of a large number of resistant strain, makes animal’s disease-resistant ability drop. At the same time also causes veterinary drug residues which get into the human body and ecological system, harm the human health. Therefore, establishing a fast, effective, sensitive and stable detection method which simultaneously detects multiple veterinary drug molecular is very important.In this article, two kinds of molecularly imprinted polymers was prepared using enrofloxacin and ractopamine respectly as template and silica gel as support material by coupling surface imprinting with a sol-gel process. The results of adsorption experiments indicated that the two imprinted polymers had better adsorption capability and selectivity for their own templates respectly.A method was developed with the two prepared polymers which filled in the solid phase extraction column in turn as solid-phase extraction sorbent combining with high performance liquid chromatography for the analysis and detection of the two veterinary drug molecular. And the parameters affecting the procedure including the pH, sampie flow velocity, elution solvent, elution volume were optimized in this research. Finally pH4.5, a flow rate of 1.0 mL min-1,5 mL acidified methanol as elution solvent were identified as the optimal condition. Under this condition, with a flow rate of 1.0 mL min-1 for sampling 100 mL of 1 μg L-1 mixed standard- H3PO4 solution, the enrichment times of enrofloxacin has achieved 91, the enrichment times of ractopamine has achieved 80; the LODs (S/N=3) of enrofloxacin was 10 μg L-1, the LODs (S/N=3) of ractopamine was 6 μg L-1; both of relative standard deviation of the two veterinary drug molecular with nine repeated determinations were below 4.33%; the linear range of enrofloxacin was 0.5-15 μg L-1, the linear range of ractopamine was 0.5-10 μg L-1.To evaluate the applicability of the developed method, the fresh samples of pork which determined with no enrofloxacin and ractopamine were spiked and determined. Three spiked levels (5 ng g-1,10 ng g-1,15 ng g-1) were setted up. After sample extracting and processing, at each concentration, recoveries of enrofloxacin under optimal experimental conditions achieved from 62.80%-71.16%, recoveries of ractopamine achieved from 57.63-63.05%. All of the relative standard deviation (RSD) were below 5.34%. It is proved that this method of detection is feasible.