Determination of the relative amounts of the B and C components of neomycin by thin-layer chromatography using fluorescence detection.

The determination of the relative amounts of the B and C components of neomycin sulphate by thin-layer chromatography using silica gel plates from Whatman as the stationary phase is described. The mobile phase consisted of methanol-20% (m/v) sodium chloride solution (15:85). Fluorescence detection was performed after derivatization with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole. The influence of different parameters on the separation was investigated. A number of commercial samples was analysed using this method and the results were compared with results obtained with ion-exchange chromatography and ninhydrin colorimetric detection, which is the official method prescribed by the European Pharmacopoeia. The described method is much easier to perform than the official method.