The quantitative surface analysis of an antioxidant additive in a lubricant oil matrix by desorption electrospray ionization mass spectrometry.
Bottom Line: The 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.The application of DESI-MS to the direct, quantitative surface analysis of a commercial lubricant additive in a native oil lubricant matrix is demonstrated.
Affiliation: Centre for Analytical Science, Department of Chemistry, Loughborough University, Loughborough, LE11 3TU, UK.Show MeSH
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Mentions: The DESI-MS analysis was conducted on a Waters Synapt HDMS quadrupole-time-of-flight (Q-TOF) mass spectrometer (Waters, Manchester, UK) which consists of a quadrupole, trap, T-wave ion mobility and transfer stacked-ring ion guide regions and a time-of-flight mass analyser. The instrument was equipped with an in-house modified DESI source equipped with a custom-built outer cone and x,y,z-manipulated sample stage. A schematic diagram of the DESI-MS source is shown in Fig. 1. The custom-built outer stainless steel cone fits over the standard inner cone of the inlet to the z-spray interface of the spectrometer, replacing the standard outer cone. A stainless steel Swagelok tube fitting (part number: SS-100-R-2, Swagelok, Manchester, UK) was welded to the cone enabling attachment of stainless steel extender tubing (1/16" (0.16 cm) o.d., 0.05 cm i.d., length 5–20 cm), which acts as an ion transfer tube for non-proximal DESI analyses.
Affiliation: Centre for Analytical Science, Department of Chemistry, Loughborough University, Loughborough, LE11 3TU, UK.