A high-frequency microtitration method is described for the determination of total acid number in new and used lubricating oils. The sample, dissolved in tolueneethanol (7 + 3), is titrated with standard alcoholic tetramethylammonium hydroxide solution. A study of solvents, titrants, sample size and other experimental parameters is reported.This method provides sharp breaks a t the end-point and more repeatable results faster than those obtained with the standard potentiometric method. The method can be expanded to the macro-scale using a commercially available titrator and offers an alternative to the ASTM and IP methods for the determination of total acid number.

No abstract