A prototype of an optical sensor for the identification of diesel oil adulterated by kerosene

Abstract Background: Liquid fuel adulteration has several far-reaching impacts such as environmental pollution. A widespread practice is typically the adulteration of diesel oil by kerosene. The relatively cheap price of kerosene is probably the most important reason for its usage in illegal adulteration. Herein, we demonstrate the use of a prototype optical sensor for efficient tracking of adulterated diesel oil. Methods: In this study, a prototype of an optical sensor for screening of fake diesel oil is proposed. The device exploits the phenomenon of laser light reflection from a fuel film over a roughened glass plate. The sensing mechanism of the devise is based on the refractive index mismatch between the glass and the fuel sample, and the wetting property of the fuel film over the roughened surface. For the sake of comparison, the refractive index for each of the fuel samples was measured at room temperature with the aid of an automatic temperature controlled Abbe table refractometer. The sensitivity of this prototype optical sensor was tested using training sets of diesel oil samples adulterated with low concentrations of kerosene. Results: Originally, a commercial handheld glossmeter, with a new innovation of a removable sensor head for liquid inspection is presented as a prototype sensor for the screening of possible adulteration of diesel oils with kerosene. The significant difference in the signal readings obtained from carefully prepared training sets of adulterated diesel oil composed of low percentages (5–15%) of kerosene has proven the high sensitivity of the developed sensor. Conclusions: The ability to detect low concentrations of kerosene in diesel using the newly developed hand-held prototype sensor proves its high sensitivity compared to a high-accuracy Abbe refractometer. We envisage that this proposed sensor could, in the future, be made accessible to the authorities as a mobile fake fuel measurement unit