Using thermal and spectroscopic data to investigate the thermal behavior of epinephrine

Epinephrine is a neurotransmitter of the catecholamine class that acts in the mammalian central nervous system. The TG-DTA curves of epinephrine showed that the anhydrous compound starts decomposition at 165 °C, under the conditions used in this work. The reflectance FTIR spectra and X-ray powder diffraction patterns of epinephrine before and after heating up to 210 °C, as well as the TG-FTIR spectra of sample heated between 30 and 600 °C, were obtained and reveled that after heating, structural changes occurred in the sample. At temperatures higher than 205 °C the thermal decomposition took place with elimination of methylamine in agreement with the first mass loss observed in the TG curve in both air and N2 atmospheres (TG = 17.0%, calcd. = 17.0%). The melting was observed at 205 °C (DTA) or 203 °C (DSC) but this process occurred overlapped with decomposition characteristic of an incongruent melting process.