Effect of sample geometry on synchronous fluorimetric analysis of petrol, diesel, kerosene and their mixtures at higher concentration
A comparison of synchronous fluorescence scan (SFS) spectra of petrol, diesel and their mixtures with kerosene in front surface, 45° and 90° angle sample geometry as obtainable from a commercial fluorimeter reveals that 90° angle sample geometry provides certain distinct characteristics to SFS spectra. The presence of extensive inner filter effects and resonance energy transfer in petroleum products are the major causes of the distinctive characteristics of these spectra. These characteristics enable the development of calibration plots for mixture samples (petrol–kerosene and diesel–kerosene) based on the shift in λSFSmax and SFS intensity. This novel method shows promise in detecting and estimating the contamination of petrol and diesel by kerosene. Calibration graphs obtained from SFS intensity measurement are found to be efficacious in the whole range 0–90% v/v of kerosene, and give a good linearity in the adulteration range generally found in the field (0–50% v/v) for petrol and diesel. The method is simple, rapid and superior both in terms of sensitivity (0.1% v/v) and accuracy to other analytical methods used for petroleum product analysis.