The determination of wax esters in lube oil by infrared spectrometry

A simple and rapid method for estimating the content of wax esters in lubricating oils has been developed through the use of isopropanol extraction to concentrate the wax esters. The ratio of the absorption bands at 1740 and 1385 cm^-1 can be used directly for the determination of wax esters in lube oil samples. The method can be satisfactorily applied at levels down to 1 %, with an overall deviation of less than 10 %; for samples containing as low as 0.5 %, the procedure can be used semi-quantitatively with an error of about 20 %. This infrared method can also be used to determine marine and sulfurized wax esters.