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Polycyclic aromatic hydrocarbons are
ubiquitous in nature present in petroleum products in varying
concentrations. They are used as a marker for chemical
fingerprinting of crude oil, adulteration detection of kerosene in
petrol and diesel, source liability determination in environmental
contamination, and oil spill cases. In forensic investigation
chromatographic methods used are expensive and increases cost of
analysis per sample. Hence, replacement of chromatographic technique
with low cost, simple, and sensitive method of analysis is required.
Conventional fluorescence spectroscopy and synchronous fluorescence
spectroscopy (SFS) method was compared for their application in
forensic study. Pure kerosene, diesel and petrol samples, and six
different brands of diesel samples were analyzed with conventional
method. Six diesel samples were analyzed with developed SFS method.
For adulteration detection, diesel sample was simulated with
kerosene sample 0.1 to 50% concentration and then analyzed with SFS.
Conventional fluorescence spectroscopy does not show sharpness in
fluorescence intensity, whereas SFS shows well separated sharp
fluorescence intensity peaks. As the concentration of kerosene
increases in the diesel, it causes self-quenching of diesel
fluorescence, subsequently decreasing the intensity of fluorescence
spectra. From present study, it is concluded that synchronous
spectrofluorimetry needs to be developed and included in forensic
laboratories for routine petroleum product analysis that can replace
traditional method of analysis.
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Key words: Adulteration,
Oil spill, Petroleum product, Polycyclic aromatic hydrocarbons,
Synchronous fluorescence
spectroscopy |
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