5.1.4. Chemical Degradation Analysis

The most standard approach to monitor and/or detect chemical degradation is analysis using (U)HPLC. Impurities or degradation products often present as new peaks; however, recognition of additional products often requires the use of techniques such as liquid chromatography-mass spectrometry (LC-MS). Degradation of molecules can be induced using harsh processing conditions, and exact knowledge of the chemistry of

unwanted products is crucial in order to recognize and avoid potentially problematic process steps [163].

Vibrational spectroscopic methods may also be used to determine whether a chemical change has taken place during the process of manufacture and storage. The disappearance of peaks associated with key frequencies of the API could be an indication of degradation. FTIR and RS have been used to ascertain that NCM formulated for the delivery of lamivudine-zidovudine [19,42,111], tadalafil [169], and diclofenac [170] had not undergone chemical degradation or chemically interacted with the stabilizers.

While less commonly used for the purposes of determination chemical degradation, SEM-EDX may offer valuable information regarding the state of the NCM within a bulk. The technique was effectively used to determine whether chemical degradation had occurred by revealing the disappearance of elemental peaks of the appearance of new ones. In addition, the percentage of abundance was equally used as a determinant of chemical degradation for the NCM [42].
