Abstract: 【Objective】 The detection methods of the related substances in cefquinome sulfate intramammary infusion were optimized by referencing the cefquinome sulfate injection in Veterinary Drug Quality Standard Assembly. A specific, sensitive, simple and rapid method was developed, which could be used to analyze the related substance in cefquinome sulfate intramammary infusion, effectively. And it will be useful for its quality control and process optimization. 【Method】 The instrument method was made by the pharmacopoeia requirements. The separation was performed on sodium perchlorate buffer (3.45 g NaClO₄·H₂O was dissolved in 1 000 mL water, mixed in 12 mL phosphoric acid and 115 mL acetonitrile, and adjusted pH to 3.6 with triethylamine) as the mobile phase at flow rate of 1.0 mL·min^-1. The detection wave length was 270 nm and the injection amount of sample solution was 20 µL. The LOD and concentration of the related substance in cefquinome sulfate were estimated by HPLC area normalization method. The linearity, the RSD of injection precision and method precision were tested. For the specificity test, by using 0.2 mol·L^-1 HCL, 0.2 mol·L^-1 NaOH to destroy the drug for 4 h, using 10% H₂O₂ to destroy the drug for 30 min and 90℃ high temperature to destroy the drug for 1 h. The before and after destroyed samples were detected by HPLC after preparation. And the main-substances’ area, related-substances’ concentration, and their resolutions were contrasted with each other, and the number of the peak values of the impurities was also contrasted. 【Result】 After a series of dilutions of the cefquinome sulfate intramammary infusion, when the concerntration of the main component was at 7.5 µg·mL^-1, the S/N of the related-substance was no less than 3, and through calculation of the LOD of the related substance was 0.05 µg·mL^-1, and the RSD of injection precision and method precision of 100 µg·mL^-1 were 0.8% and 0.6%, respectively. The calibration curve of the related substances was a liner equation as y = 45935x-130.03 with a correlation coefficient of 1. The infusions were degraded by almost 10%, 10%, 30%, and 20% under the conditions of acid, alkali, an oxidizing agent, and high temperature, respectively. The retention time and resolution of cefquinome and related-substances were good, and the concentration and numbers of the impurities were added. After detecting the concentration of related substances of the 3 batches of cefquinome sulfate intramammary infusion, and calculated by HPLC method, it was found that the area of related substances were less than 2% of Cef, which met the the Quality Standards of Veterinary Drugs Provisions. 【Conclusion】 The method is simple and easy, selective and sensitive, which can be used to analyze the related substances in agents efficiently.

Key words: cefquinome sulfate intramammary infusion, related substance, HPLC method