Fingerprinting of Octane Rating Gasoline and its Contaminants Using Synchronous Fluorescence Spectroscopy

Fuel fraud has proliferated due to underlying economic advantage in nearly every nation. For the purpose of detecting adulteration and providing real-time quality assurance, non-destructive oil analysis is crucial. This paper reports the simple approach for fingerprinting undiluted petroleum products including gasoline from various brands, diesel, and kerosene oil in comparison with organic solvents using synchronous fluorescence spectroscopy and hierarchical cluster analysis. Fluorescence-based successful detection of adulterated samples is demonstrated in imported RON 92 gasoline, synthetically adulterated with kerosene oil (KO) in proportions up to 70%. Compared to gasoline, kerosene oil has a lower relative poly aromatic hydrocarbons, as the amount of kerosene oil (KO) increases, the KO peak at 352 nm rises, but the gasoline's peak intensity decreases in the range of 371-500 nm. It is noteworthy that imported fuel grades RON 92 and RON 95 are comparable to each other and surprisingly clustered with RON 91 from the Attock refinery presenting concerns about quality. Similarly, the Shell website mentions that Shell V-Power is RON 99 but interestingly it clusters with retail fuel samples acquired from PSO filling stations and PSO RON 95 showing disagreement with the claim that the fuel is high octane. Another use for this technique in oil exploration was the detection of adulterants and successfully spotted methanol, ethanol, and kerosene oil in the tainted samples. These findings suggest SFS as an accurate, and low-cost testing tool for gasoline fingerprinting and contamination screening.