QUANTITATIVE TLC OF ERYTHROMYCIN - APPLICATION TO COMMERCIAL BULK SAMPLES AND BIOLOGICAL SAMPLES

A quantitative thin layer chromatographic (TLC) method on silica gel, with dichloromethane - methanol - 25% m/m ammonia (90 + 9 + 1.5, nu/nu ) as mobile phase, has been developed for the analysis of bulk erythro mycin. Detection by post-chromatographic color reaction was achieved b y spraying with 0.15% m/nu xanthydrol in concentrated hydrochloric aci d - acetic acid (90 + 7.5) and then heating the plate. Spots were quan titated by scanning at lambda = 525 nm, using troleandomycin as intern al standard. The main component, erythromycin A, was separated from al l related substances present in commercial samples except erythromycin s B and E. Results for some commercial samples obtained by this TLC me thod correlated well with those obtained by a previously established L C technique. The TLC method separates erythromycin D from erythromycin A; this is not possible by LC. The application of this TLC method to biological samples of erythromycin is also reported.