Characterization of ageing products of ester-based synthetic lubricants byliquid chromatography with electrospray ionization mass spectrometry and by electrospray ionization (tandem) mass spectrometry

Ageing products of a commercial jet engine oil based on pentaerythritol tet raesters which were formed upon operation in an aviation turbine were detec ted by electrospray ionization mass spectrometry (ESI-MS) and characterized by LC-ESI-MS. The fatty acid composition of these ageing products was inve stigated by ESI-MS-MS analysis. The ammonium adducts of the newly formed pe ntaerythritol tetraester degradation products were found to be suitable par ent ions for further structure elucidation work. ESI-MS, LC-ESI-MS and ESI- MS-MS proved to be versatile tools to study the chemical composition (distr ibution of homologues) as well as the mechanism of ageing of ester based lu bricants on a molecular level. Due to its high sensitivity, ESI-MS can also be used to characterize and identify trace levels of ester-based lubricant s. (C) 2001 Elsevier Science B.V. All rights reserved.