Gas-liquid chromatographic determination of antibiotic X-537A, lasalocid

A method is described for the chemical analysis of lasalocid, formerly known as antibiotic X-537A. The method is based on quantitative thermolysis of the antibiotic to a retroaldol ketone which is assayed by gas chromatography. No catalyst or special pyrolysis attachment is needed for the assay, as cleavage of the antibiotic is complete in the injection port of the gas chromatograph. This technique has the advantage that no derivatization step is necessary prior to analysis.