Rapid determination of the carboxylic acid contribution to the total acid number of lubricants by Fourier transform infrared spectroscopy

摘要

A Fourier transform infrared (FTIR) spectroscopic method was developed to rapidly and quantitatively determine the contribution of carboxylic acids to the Total Acid Number (TAN) of lubricating oils. The method is based on measurement of the carboxylic acids present as a result of oil oxidation and employs differential spectra in order to eliminate interferences from other components present in the oil.