Monitoring petroleum fuel adulteration: A review of analytical methods

Detection of adulteration in the petroleum fuels (gasoline and diesel) is challenging because the adulterants usually include those compounds which are already present in these fuels. Measurements of various physico-chemical properties are employed in addition to chromatography and spectroscopy for determining the compositional variations of these fuels. It is required to ensure their compliance with the regulatory specifications. The inclusion of statistical design and data treatments certainly provide enough sensitivity to discriminate adulterated and unadulterated samples in the case of gasoline. On the contrary, discrimination of diesel from its adulterants is difficult which demands rigorous analytical strategies and unequivocal data interpretation. Through this review, we have attempted to organize the literature information on this subject with an emphasis to identify and optimize methods suitable for monitoring adulteration. Detailed discussions on the role of physico-chemical, chromatographic and spectroscopic methods in gasoline and diesel characterization have been presented.