Determination of zinc dialkyldithiophosphate additives in lubricating oil by photometric titration

Abstract

A photometric titration, using p-dimethylaminophenylmercury(II) acetate with Michler's thioketone as indicator, is described for the determination of zinc dialkyldithiophosphates in lubricating oils. The method is simple, rapid, reproducible and accurate and samples do not require separation or other preliminary stages prior to their analysis. The method is suitable for determining additives in oils at concentrations above 0.01%.