Fourier-transfer Infra Red Spectroscopy (FTIR) is a powerful tool for analysis of oil, grease and fuel samples. It is especially useful for monitoring and identifying certain types of contaminants.
The underlying principle is that infrared energy from the source is absorbed in the sample at wave lengths which are characteristic of specific molecular bonds. Each scan generates an FTIR spectrum which can be analysed and interpreted.
At its most basic the technique can be used to measure predetermined parameters, such as oxidation, nitration, sulphation or presence of fuel and glycol in an engine oil. Some of those require prior calibration and a scan of a virgin sample to be used as reference.
More advanced analysis can help monitor degradation, identify and match unknown contaminants, verify lubricant formulation or help identify and source an unknown lubricant.
In some cases Gas Chromatography coupled to Mass Spectroscopy (GC-MS) is called upon to work in tandem with FTIR analysis on particularly tricky samples, where exacting information is nonetheless required.
You can download an Example FTIR Report here