Development of an accelerated artificial ageing method for the characterization of degradation products of antioxidants in lubricants by mass spectrometry.

The understanding of ageing mechanisms of antioxidants in base oils is indispensable for the development of improved lubricants. In this study, a novel artificial ageing method based on the application of peroxide as oxidant is presented for improved monitoring of thermo-oxidative degradation processes in combination with mass spectrometry. Model oils containing aminic and phenolic antioxidants were aged and chemical structures of their oxidation products were elucidated by ultrahigh performance liquid chromatography and electrospray ionization high resolution (Orbitrap) mass spectrometry.

Ultrahigh-performance liquid chromatography/electrospray ionization linear ion trap Orbitrap mass spectrometry of antioxidants (amines and phenols) applied in lubricant engineering.

Rationale: For the qualification and quantification of antioxidants (aromatic amines and sterically hindered phenols), most of them applied as lubricant additives, two ultrahigh-performance liquid chromatography (UHPLC) electrospray ionization mass spectrometric methods applying the positive and negative ion mode have been developed for lubricant design and engineering thus allowing e.g. the study of the degradation of lubricants.

CID of singly charged antioxidants applied in lubricants by means of a 3D ion trap and a linear ion trap-Orbitrap mass spectrometer.

The aim of this study was to investigate the fragmentation behavior induced by low-energy collision-induced dissociation (LE-CID) of four selected antioxidants applied in lubricants, by two different types of ion trap mass spectrometers: a three-dimensional ion trap (3D-IT) and a linear IT (LIT) Orbitrap MS. Two sterically hindered phenols and two aromatic amines were selected as model compounds representing different antioxidant classes and were characterized by positive-ion electrospray ionization (ESI) and LE-CID. Various types of molecular ions (e.

Different target surfaces for the analysis of peptides, peptide mixtures and peptide mass fingerprints by AP-MALDI ion trap-mass spectrometry.

The desorption/ionization behavior of individual peptides, an equimolare peptide mixture and a tryptic digest was investigated by AP-MALDI-IT-MS using four different target materials (gold-covered stainless steel (SS), titanium nitride-covered SS, hand-polished SS, and microdiamond-covered hardmetal) under identical conditions. Gold-covered as well as polished SS targets yielded comparable mass spectra for peptides and peptide mixture in the low pMol-range. The first target exhibited superior data down to the 10fMol-range.

Electrospray ionization and atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry of antioxidants applied in lubricants.

The aim of this study was to investigate the utility of ion trap mass spectrometry (ITMS) in combination with the two desorption/ionization methods, electrospray (ESI) and atmospheric pressure matrix-assisted laser desorption/ionization (AP-MALDI), for the detection of antioxidants which are applied in lubricants. These experiments should form the base for future investigations of antioxidants in tribologically formed thin layers on the surface of frictional systems. Seventeen different antioxidants were selected out of the group of hindered phenolic and aromatic aminic compounds.