Differentiation of used motor oils on the basis of their IR spectra with application of cluster analysis

Two brands of motor oils, Elf and Castrol, were examined for criminalistic purposes. The aim was to distinguish between oil samples of varying degree of use. The chemical composition of the oils expressed by their infrared spectra was the basis of investigations. The mathematical approach applied to processing and interpretation of the physicochemical data was a chemometric procedure consisting of a few stages and including such methods as factor and cluster analysis. It was shown that the procedure presented can be recommended as very helpful for qualitative estimation of the effects examined.