Lubricating synthetic oils, used in gas turbine engines of aircraft, are generally made up of esters of branched-chain alcohols. Some additives are added to the base of synthetic oil improving the lubrication performance efficiency and avoiding corrosion, wear, and oxidation phenomena. Antioxidants used are generally composed of hindered phenols or aromatic amines in a concentration range of Ž . 0.25᎐5% wrw . Antiwear additives are generally made up of phosphorus com-Ž . pounds and they should be less than 3% wrw . In this paper, two methods are described determining additives found in lubricating oils. Both methods, based on gas chromatographic techniques, were used to measure these additives in several samples of synthetic oils, before and after accelerated oxidation. The first method is based on a gas chromatography mass spectrometer detector in selected ions monitoring, whereas the second one on a flame photometric detector with an optical filter selective for phosphorus compounds. These techniques, because of their selectivity, do not require sample pretreatments other than a dilution and addition of an internal standard and can be a useful tool evaluating ageing of lubricants in gas turbine engines. Analysis of 1᎐5 mL oil sample can be performed in less than 30 min. Sensitivity, reproducibility, and accuracy data of the methods are reported.

Lubricating synthetic oils, used in gas turbine engines of aircraft, are generally made up of esters of branched‐chain alcohols. Some additives are added to the base of synthetic oil improving the lubrication performance efficiency and avoiding corrosion, wear, and oxidation phenomena. Antioxidants used are generally composed of hindered phenols or aromatic amines in a concentration range of 0.25–5% (w/w). Antiwear additives are generally made up of phosphorus compounds and they should be less than 3% (w/w). In this paper, two methods are described determining additives found in lubricating oils. Both methods, based on gas chromatographic techniques, were used to measure these additives in several samples of synthetic oils, before and after accelerated oxidation. The first method is based on a gas chromatography mass spectrometer detector in selected ions monitoring, whereas the second one on a flame photometric detector with an optical filter selective for phosphorus compounds. These techniques, because of their selectivity, do not require sample pretreatments other than a dilution and addition of an internal standard and can be a useful tool evaluating ageing of lubricants in gas turbine engines. Analysis of 1–5 mL oil sample can be performed in less than 30 min. Sensitivity, reproducibility, and accuracy data of the methods are reported. ©2001 John Wiley & Sons, Inc. J Micro Sep 12: 585–592, 2000