Liquid chromatographic determination of zoalene in medicated feeds

A rapid, reliable separation and quantitation of zoalene (3,5-dinitro-o-toluamide) from feeds is accomplished by using reverse phase liquid chromatography (LC) and ultraviolet detection. An extraction technique which is similar to the present AOAC official colorimetric method is used before chromatographic analysis. This extraction is followed by an activated alumina cleanup and LC to separate zoalene from feed matrix. The methodology was applied to a variety of spiked feed matrices, and yielded good recoveries. Liquid chromatographic results were shown to correlate with colorimetric determinations.