The thermal behavior of oxytetracycline hydrochloride (OTC) antibiotic was evaluated using TG-DTA, TG-FTIR and DSC. Information was obtained regarding thermal stability and decomposition steps. From TG-FTIR, it was possible to identify some of the products of its thermal decomposition as chloridric acid, water, isocyanic acid, dimethylamine, methane, carbonic gas and ammonia, and carbon dioxide from the decomposition of the isocyanic acid. According to DSC data, melting occurred concomitantly with decomposition. The TG/DTG, DTA and DSC curves, together with the FTIR spectra of the volatile decomposition products, were used to propose a mechanism for oxytetracycline decomposition.
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