Journal of AOAC International 2010-01-01

Quantitative analysis of closantel and rafoxanide in bovine and ovine muscles by high-performance liquid chromatography with fluorescence detection.

Hoi-Sze Yeung, Wing-Hong Ching, Shirley Sau-Ling Lai, Wai-On Lee, Yiu-Tung Wong

Index: J. AOAC Int. 93(5) , 1672-7, (2010)

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Abstract

An HPLC method with a fluorescence detector (HPLC-FLD) was described for the quantitative determination of closantel and rafoxanide in bovine and ovine muscles. A structural analog closely related to rafoxanide, viz., N-[4-(4-chlorophenoxy)phenyl]-2-hydroxy-3,5-diiodobenzamide, was synthesized as an internal standard. Bovine and ovine muscles were extracted with acetonitrile-acetone (60 + 40, v/v) followed by cleanup on mixed mode anionic exchange SPE cartridges. After evaporation and reconstitution with the mobile phase, the sample was analyzed by HPLC-FLD using internal standard calibration. The method was validated by using fortified bovine and ovine muscles at 15, 30, and 60 microg/kg. The accuracy and RSD were 70-110% and < or =10%, respectively.