1H and 13C Analysis of Residues (Gasoline/Diesel/Lubricants)
Using various preperative techniques (dialysis, evaporation under nitrogen blanket, washing with a solvent series of differing polarity) samples can be prepared for NMR analysis that can yield information on the following:
- Additive Chemistry – PIB amines, polyether based detergents (molecular structure and size can be determined), carrier fluids, emulsifiers, cetane enhancer.
- Blow-by severity can be deduced from aromatic content observed by NMR.
In lubricants additive chemistry can be observed:
- Ethylene propylene VI improver can be observed and backbone sequence deduced (E-P ratio, block size distribution).
- Anti wear chemistry can be deduced (ZnDTP, MoDTP)
- PIB dispersency can be observed – discrepancies in PIB content can lead to information on blow by from fuel side of piston.
- In used oils presence of fuel additives can be observed and viscosity issues with used oils can be equated to presence of these additives.
Solvent-series washed additives can be “reverse engineered” to yield important information on various additive structure as as well as relative quantitation.
An example of what can be observed by evaporating gasoline samples is shown below. The two gasolines were supposed to be identical – the NMR analysis showed serious differences in the heavy aromatic components present in the sample. Differences in additive treat level (PIB detergent with propylene oxide based fluidizer) were also observed.