Colorimetric Determination of Ronidazole in Feeds
Abstract Ronidazole, (l-melhyl-5-nitroimidazoI- 2-yl)mcthyl carbamate, is extracted from finished poultry feeds with methanol and chromatographcd on an AL2O3-FIorex column. The eluate is concentrated and dissolved in CCI4 and the ronidazole is extracted with. H2O. The purified ronidazole is hydrolyzcd in NaOH solution in the presence of copper and p-aminobenzoic acid; the resulting diazonium compound is then coupled with naphthylethylenediamine to form a colored complex, which is measured spectrophotometrically at 550 mµ. No significant interference was found from finished feeds, domestic and foreign, or from 48 common feed additives. Recovery experiments on 36 laboratory-prepared feed samples at levels ranging from 0.0015 to 0.030% ronidazole averaged 100.8% with a standard deviation of 2.4.