Determination of tiamulin hydrogen fumarate in animal feeds using high-performance liquid chromatography

Abstract

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.