Identification of volatile degradants in formulations containing sesame oil using SPME/GC/MS

Solid-phase microextraction (SPME), in combination with gas chromatography/mass spectrometry (GC/MS), was used to identify an unknown degradant observed during stability studies of a pharmaceutical formulation containing sesame oil. SPME is a solvent-less, rapid, sensitive, and inexpensive extraction method that minimizes sample preparation. SPME combined with GC is a widely used technique in certain fields, such as food, environmental analysis, forensics, and consumer products, but has only rarely been used for the analysis of pharmaceutical formulations. Hexanal, octanal, 2-octenal, 2-decenal, 2-undecenal, and 2,4-decadienal can be detected and identified by GC/MS, but they cannot be detected by LC/MS due to their volatility and low ionization efficiency under atmospheric pressure ionization conditions. Combining the MS data from the GC/MS with LC/DAD data resulted in the identification of the unknown degradant in the formulation as 2,4-decadienal. The presence of this and other aldehydes was attributed to the oxidative degradation of the unsaturated fatty-acid component in vegetable oils.