Differentiation between used motor oils on the basis of their IR spectra with application of the correlation method

Two brands of motor oils (Elf and Castrol) that had been used for various periods of time were examined. The aim was to differentiate these samples (of varying degree of use) on the basis of their infrared spectra, for criminalistic purposes. The correlation method was used. It was found that the FTIR method is capable of providing sufficiently detailed information if some specific fragments of spectra are examined. Hence, it can be concluded that the investigation procedure proposed is adequate.