Qualitative and Quantitative Analysis of Zinc Dialkyldithiophosphates in Lubricating Oils using High Performance Liquid Chromatography

Abstract

A new procedure that readily allows to idnetify and quantify zinc dialkyldithiophosphates(ZDTPs) formulated in lubricating oils using high performance liquid chromatography with UV detector has been developed. This procedure utilized derivatives of highly UV active anthracenylmethyl dialkyldethiophosphates(AMDTPs) from the reaction of ZDTPs and 9-chloromethylanthracene(CMA). Types of alkyl groups in commercial ZDTPs were readily analyzed with this procedure. Since it was confirmed that none of lubricating oil additives other than ZDTPs reacts with CMA and forms its derivatives, this procedure was suitably applied to the analysis of ZDTPs in formulated lubricating oils.