Application Note

Determination of Total Base Number (TBN) and Total Acid Number (TAN) in Lubricants Using FT-IR Spectroscopy and Multivariate Analysis


Oil additives are chemical compounds that are added to lubricating oils to improve their performance for specific applications. The additives are designed to be consumed over the lifetime of the lubricant and, as such, will break down and form new compounds as the lubricant ages. The concentration of these breakdown products, which may be acidic or basic in nature, can be used to assess the quality of the oil.

The Total Base Number (TBN) is a measure of the alkaline concentration present in a lubricating oil sample whereas the Total Acid Number (TAN) is a measurement of the acidity of the sample. This application note describes how samples of lubricant were analyzed for TAN and TBN using a PerkinElmer OilExpress 4 system.