Qualitative Identification of Chlortetracycline and Oxytetracycline in Feeds

Abstract A microscopic method is given for the qualitative differentiation and identification of chlortetracycline and oxytetracycline in mixed feeds at levels usually encountered. Identification depends upon the colors produced by the antibiotics as they pass into solution in modified Sakaguchi reagent 1% boric acid in 70% H2S04, i.e., intense red for oxytetracycline and intense purple for chlortetracycline. Collaborative study gave excellent agreement, and the method is recommended for adoption as official, first action.