Rotrode filter spectroscopy - A method for multi-elemental analysis of particles in used lubricating oil

A convenient and economical method has been developed To provide additional spectrometric analysis of the wear particles in used oil samples. It has b een recognized for some time that spectroscopy is more or less blind to the larger particles in an oil sample, precisely those particles which are som etimes most indicative of an abnormal wear mode. The rotrode filter spectro scopy (RFS) method makes use of the fact that the carbon disc electrode use d in a rotating disc electrode (RDE) spectrometer is itself porous and may be used as a filter A fixture was designed so that a used oil sample is pul led through the disc which is then washed with solvent thus retaining only particulates on the outer circumference of the disc. The disc is subsequent ly "burned" on a spectrometer providing an analysis of larger particulates in a sample.