Abstract: In order to detect the content and related substances of oxyclozanide suspension, a new method using high performance liquid chromatography (HPLC) was established. Content determination was carried out using Hypersil BDS C18 (150 mm×4.6 mm, 5 μm) column and 0.1% phosphoric acid water-method (volume ratio=38:62) as mobile phase, column temperature was 25 ℃, and determination wavelength was 300 nm. Related substances was carried out using InertSustainSwift C18 (150 mm×4.0 mm,5μm) column, mobile phase, detection wavelength and column temperature were the same as the content determination method. The results showed that liner range of content determination of oxyclozanide suspension were 34.01-104.35 μg·mL^-1 (R²=1.000), and average recovery was 100.1%. The liner range of 2-amino-4, 6-dichlorophenol hydrochloride and 3, 5, 6-trichlorosalicylic acid were 0.51-20.4 μg·mL^-1 (R²=0.996, 1.000, respectively), and average recovery were 110.3% and 98.6%, respectively. It showed that the method was convenient, simple and accurate, and could simultaneously determine the content and related substances of oxyclozanide suspension, and provided standards for quality control of the product.

Key words: HPLC, oxyclozanide, linear range, the average recovery rate