A Colorimetric Method, based on Metallic Complex Formation, for the Detection of Aureomycin in Presence of Amino-Acids and Proteins

Abstract

EXPERIMENTS involving the feeding of aureomycin to animals are now so common that it would be an advantage to have a rapid and reliable chemical method for its detection in body fluids and similar media. This is the more desirable since microbiological methods of assay are not easy to carry out because of the instability of the antibiotic in ordinary bacteriological media, even at 25°^1,2. There is one remarkable chemical property of aureomycin, apparently not yet recorded in the literature, which might be made use of to this end, namely, its ability in alkaline solution to form stable, yellow complexes, soluble in n-butanol, with certain divalent cations only, notably Mg, Ca, Co, Ni, Cu and Sr. Zn, Cd, Mn, Ba, Hg and Pb do not form stable coloured complexes. Aureomycin alone gives, of course, a yellow colour with excess of ammonia or caustic soda, but this fades quite quickly and irreversibly at 30°, a purple fluorescence developing in its place. Shaking with n-butanol then extracts no colour.