Autoxidation of fats and oils

Compounds of this type are called triglycerides and contain several sites within the molecule where autoxidation can occur to cause breakdown of the molecule. This is especially true if the fatty acids are unsaturated (i.e. contain at least one carbon-carbon double bond if the carbon chain contains several double bonds, the oil is said to be polyunsaturated). 

These oils, if they are to be used parenterally, need to be chemically pure and free from microbial contamination. As stated above, plant oils are often complex mixtures of chemically similar compounds and so require special forms of pharmaceutical assay (e.g. determination of their acid and 

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