Thermally induced structural changes of acetaminophen in phase transition between the solid and liquid states monitored by combination analysis of FT-IR/DSC microscopic system

The molecular structure of acetaminophen in solid/liquid phase transition states was simply investigated by Fourier transform infrared (FT-IR) microspectroscopy equipped with differential scanning calorimetry (DSC). The result indicated that the intermolecular hydrogen bonds in the solid-state acetaminophen molecules were dramatically broken from 165°C, and loosened its molecular structure and packing to induce the phase transition between solid and liquid states. This study clearly shows that the microscopic FT-IR/DSC system is a useful tool for easy investigation of the changes in hydrogen bonding at the solid and liquid states of acetaminophen.