Determination of tiamulin hydrogen fumarate in animal feeds using high-performance liquid chromatography
A stability-indicating procedure is described for the quantitative measurement of tiamulin hydrogen fumarate in animal feeds at levels of 10 and 120 µg g–1. The tiamulin hydrogen fumarate is extracted from the feed with a solution of ethyl acetate in hexane (25%V/V) in the presence of sodium carbonate solution (1%m/V). The tiamulin base is then back-extracted into tartaric acid solution (0.1%m/V), which is introduced on to the column by loop injection. Owing to the very low ultraviolet absorption of tiamulin, large injection volumes were required in order to obtain a response suitable for quantitation. Injection volumes as high as 3 ml have been made without any significant broadening or distortion of the tiamulin peak.