Stability studies of tetracycline in methanol solution

The stability of tetracycline in methanol solution was investigated by UV-v isible spectroscopy, HPLC and TLC methods. After dissolution in methanol, t etracycline decomposed rapidly under the influence of light and atmospheric oxygen, forming more than fourteen different degradation products. None of the previously reported degradation products, such as the epi- and anhydro -compounds, were detected as the final degradation products. The molecular structures for eight of the compounds were suggested by their product-ion m ass spectra. A degradation sequence was proposed for the reactions of tetra cycline with methanol. A new HPLC-MS mobile phase was developed, which solv ed the clogging problem at the interface between the HPLC and MS chamber an d enabled a high separation efficiency. (C) 1998 Published by Elsevier Scie nce B.V. All rights reserved.