Particle size independent spectrometric determination of wear metals in aircraft lubricating oils

TLDR: In this article, a method for the particle size independent determination of Ni, Fe, Mg, Cu, Al, Sn, Mo and Ti in synthetic ester lubricating oils by spectrometric analysis is presented.

Abstract: A method for the particle size independent determination of Ni, Fe, Mg, Cu, Al, Sn, Mo, and Ti in synthetic ester lubricating oils by spectrometric analysis is presented. Partial dissolution of Cr, Si, Pb, and Ag also occurs. Used ester lubricating oils as well as samples prepared with -325 mesh (44 ..mu..m) or -200 mesh (74 ..mu..m) metal powders were reacted with a small amount of hydrofluoric acid and aqua regia at 65/sup 0/C for 45 min with ultrasonic agitation. The reacted mixture was then diluted with a methyl isobutyl ketone and isopropyl alcohol mixture and analyzed spectrometrically. The recoveries for metal powder suspensions of Ni, Fe, Mg, Cu, Al, Sn, Mo, and Ti ranged from 97 to 103% and the relative standard deviation ranged from 4 to 10%. In addition to the metal powder suspensions, over 200 aircraft oil samples were analyzed. The method is much faster and more convenient than previously reported particle size independent methods using ashing techniques.