Applications of Mass Spectrometric Techniques to the Analysis of Fuels and Lubricants

Abstract

The application of mass spectrometric techniques for the analysis of the complex mixtures inherent in fuel and lubricant samples will be examined. These samples because they are naturally complex mixtures, typically requires either very high resolution mass spectrometry or one of the hyphenated techniques gas chromatography-mass spectrometry(GC-MS) or liquid chromatography-mass spectrometry (LC-MS). Some fuel problems that can be addressed through mass spectrometry are associated with the changes in composition and degradation of fuels as they age, including the analysis of both major hydrocarbon components non-polar components and minor polar components will be described. The properties and composition of natural and major classes of synthetic lubricants, the presence of additives and the problems that develop as the lubricant is used such as additive depletion, thermal and oxidative degradation and lubricant contamination have also been examined using mass spectrometric techniques.

Elucidation of Low Molecular Weight Polymers in Vehicular Engine Deposits by Multidimensional Mass Spectrometry

“…The composition of polymer blends that give convoluted mass spectra could be effectively visualized by postacquisition Kendrick analysis using fractional base units. Our study also affirmed that different mass spectrometry techniques can be used cooperatively, either in series (as in LC-IM-MS) or in parallel (as in MALDI-MS vs ASAP-MS vs LC-MS), for the elucidation of complex fuels and fuel byproducts; this approach, which had been applied previously to fuels and fuel additives, ,,,, was successfully extended in this study for the first time to vehicular engine deposits. Overall, specific low molecular weight polymer structures could be detected and identified in a completely unknown sample that was examined using various separation methods and accurate mass measurements.…”

“…The (macro)molecular components found in the deposit are polar or amphiphilic; thus, they contain the structural features needed to develop noncovalent intermolecular interactions, via hydrogen bonding, electrostatic attraction, and/or coacervation, which are thought to be the cause of deposition/ particulate accumulation in vehicular engines. 17 Assessing the nature of the polar or amphiphilic components present in these deposits provides a better understanding of these unintended byproduct buildups and facilitates progress toward their prevention.…”

“…Various mass spectrometry methods have been used for the analysis of petroleum-based fuels and lubricants, , including tandem mass spectrometry (MS/MS), liquid chromatography-MS (LC-MS), ion mobility-MS (IM-MS), and atmospheric solids analysis probe-MS (ASAP-MS). − The most recently introduced ASAP-MS technique allows for the direct analysis of liquid and solid samples with little to no sample preparation . This feature makes ASAP-MS particularly appealing for the analysis of fuels and fuel byproducts, as it bypasses solubility issues and time-consuming extraction processes. , MS/MS, LC-MS, and IM-MS can also provide useful analytical information about these samples; specifically, MS/MS can reveal connectivity insight about the ions observed by MS, whereas the LC and IM event add necessary separation dimensions to deconvolute complex spectra. ,, Several of these techniques can also be interfaced with one another to reduce sample complexity, speed up the analysis, and augment the derived structural information.…”

“…While fuel and lubricant components are largely nonpolar (cf. Table 1), the more polar ingredients are often responsible for the formation of engine deposits 17 due to their heteroatom functionality (primarily amines, thiols, and ethers), which promotes attractive intermolecular interactions and aggregation. These deposits compromise engine performance, making necessary their identification, so that cleaner burning fuels can be developed.…”

“…Mass spectrometry (MS) provides compositional and structural information by generating and analyzing ions, a process that is generally more easily applied to polar, heteroatom containing molecules; hence the more polar engine deposits are uniquely amenable to this technique. Various mass spectrometry methods have been used for the analysis of petroleum-based fuels and lubricants, 17,18 including tandem mass spectrometry (MS/MS), liquid chromatography-MS (LC-MS), ion mobility-MS (IM-MS), and atmospheric solids analysis probe-MS (ASAP-MS). 19−22 The most recently introduced ASAP-MS technique 23 allows for the direct analysis of liquid and solid samples with little to no sample preparation.…”