Further studies on the colorimetric determination of ronidazole in feeds.

A previously published colorimetric method for determining ronidazole, (1-methyl-5-nitro-imidazol-2-yl)methyl carbamate, can be used as an analytical technique for measuring the stability of this drug in medicated feeds. Although the color reaction per se is not selective, elution profiles of ronidazole and its demonstrated hydrolytic degradation product, 1-methyl-2-hydroxymethyl-5-nitroimidazole, show that the chromatographic separation used in the sample preparation efficiently isolates the drug from the degradation product. No interference was found in feeds containing 0.010% ronidazole and up to 0.010% degradation product.