Improvement of Determination Method of Oxolinic Acid Residues in Live Eel

The oxolinic acid residues in eel was extracted with methylene chloride.After expelling the solvent,the residue was treated with dilute HCl and n-hexane to remove the fat.The similar extraction process was repeated with methylene chloride.The methylene chloride was evaporated to dryness and the residue was dissolved in methanol-aqueous solution.The residue content was determined by HPLC fluorescence detector.The recovery range was 82.7%—89.4%,the limit of determination of this method was 0.005mg/kg.