Premium
The quantitative surface analysis of an antioxidant additive in a lubricant oil matrix by desorption electrospray ionization mass spectrometry
Author(s) -
Da Costa Caitlyn,
Reynolds James C.,
Whitmarsh Samuel,
Lynch Tom,
Creaser Colin S.
Publication year - 2013
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.6690
Subject(s) - chemistry , lubricant , mass spectrometry , calibration curve , repeatability , detection limit , desorption electrospray ionization , chromatography , analytical chemistry (journal) , matrix (chemical analysis) , electrospray ionization , quantitative analysis (chemistry) , electrospray , desorption , chemical ionization , ionization , ion , organic chemistry , adsorption
RATIONALE Chemical 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. METHODS 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. RESULTS An 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/mm 2 additive on spot with relative standard deviations in the range 3–14%. CONCLUSIONS The 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.