The quantitative surface analysis of an antioxidant additive in a lubricant oil matrix by desorption electrospray ionization mass spectrometry

Abstract

RATIONALEChemical additives are incorporated into commercial lubricant oils to modify the physical and chemical properties of the lubricant. The quantitative analysis of additives in oil-based lubricants deposited on a surface without extraction of the sample from the surface presents a challenge. The potential of desorption electrospray ionization mass spectrometry (DESI-MS) for the quantitative surface analysis of an oil additive in a complex oil lubricant matrix without sample extraction has been evaluated.METHODSThe quantitative surface analysis of the antioxidant additive octyl (4-hydroxy-3,5-di-tert-butylphenyl)propionate in an oil lubricant matrix was carried out by DESI-MS in the presence of 2-(pentyloxy)ethyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate as an internal standard. A quadrupole/time-of-flight mass spectrometer fitted with an in-house modified ion source enabling non-proximal DESI-MS was used for the analyses.RESULTSAn eight-point calibration curve ranging from 1 to 80 µg/spot of octyl (4-hydroxy-3,5-di-tert-butylphenyl)propionate in an oil lubricant matrix and in the presence of the internal standard was used to determine the quantitative response of the DESI-MS method. The sensitivity and repeatability of the technique were assessed by conducting replicate analyses at each concentration. The limit of detection was determined to be 11 ng/mm2 additive on spot with relative standard deviations in the range 3–14%.CONCLUSIONSThe application of DESI-MS to the direct, quantitative surface analysis of a commercial lubricant additive in a native oil lubricant matrix is demonstrated. © 2013 The Authors. Rapid Communications in Mass Spectrometry published by John Wiley & Sons, Ltd.

TiO2 Photocatalysis–DESI-MS Rotating Array Platform for High-Throughput Investigation of Oxidation Reactions

“…The average relative standard deviation of the peak areas of six replicated DESI-MS-analysis of verapamil and its main oxidation products was 16%. This indicates typical repeatability of DESI-MS-analysis presented in earlier works, − although it also includes the repeatability of TiO 2 photocatalysis.…”

Antioxidants Classification and Applications in Lubricants

“…dialkylated diphenylamine) and sterically hindered phenols (e.g. 2,6-di-tert-butylphenol) are two common antioxidants which are useful in lubricants stabilization to gain synergistic effects [3,13]. A better understanding of the chemistry of antioxidants and their degradation mechanisms at the molecular level is crucial for developing more efficient lubricants.…”

DESI-MS analysis of human fluids and tissues for forensic applications

“…In order not to duplicate the data, Table 1 does not contain results included in a review a few years earlier published by Morelato et al [9]. DESI-MS method has also proved its potential in many other non-forensic applications such as food control analysis of multiple pesticides on different food surfaces [40], analysis of drugs in wastewater [41], veterinary drugs in feedstuffs [42], lubricant oil additives [43] and clinical diagnostics [21,46]. Research shows great DESI-MS potential in the analysis of lipids, proteins, protein complexes, carbohydrates, and oligonucleotides, specimens from industrial polymers to small organic molecules [44].…”