Liquid chromatographic analysis of bacitracin methylene disalicylate in feed.

Because of its peptide structure, bacitracin is not chemically distinct from many matrixes such as feeds or residue samples. Thus, bacitracin must be isolated from the matrix components or chemically altered to form a distinct component. Because of the complexity of this problem, bacitracin is still analyzed almost exclusively by microbiological methods. However, advances in solid-phase extraction has made sample isolation from the matrix much more practical. In this investigation both strong-cation exchange and C8 columns were used to isolate bacitracin for liquid chromatographic (LC) analysis. Results of both LC and microbiological analyses are compared.