The thermal behaviors of two over-the-counter medicines, A and B were studied by Thermo MassPhoto with PIMS. The major component of these medicines is metoprolol tartrate, widely used for hypertension, angina, and arrhythmia.

We found a remarkable difference of the PIMS spectra between the medicine A and B at 300℃. The both medicines evolved the two kinds of gases at 300℃, which can be differentiated by the detection of the molecular ions (m/z 152 and 192) using PIMS. The amount of the evolved gas with m/z 192 in the medicine A was 4 times as much as that in the medicine B. Thermo Mass Photo with PIMS provides fine thermal analysis of pharmaceutical products due to the soft ionization which allows us to detect molecular ions of organic gases without fragmentation.