Quantification of biodiesel content in diesel/biodiesel blends by fluorescence spectroscopy: Evaluation of the dependence on biodiesel feedstock

In a recent paper published by our group (M.D. Scherer et al. J. Fluoresc. 21 (2011) 1027–1031), we showed that fluorescence spectroscopy has a potential to be used to determine the biodiesel content in the diesel/biodiesel blends. However, this method presents some challenges that must be overcome to be successfully applied. For instance, the method must work with biodiesel produced from different vegetable oils and fats. In the present study, we evaluated the ability of fluorescence spectroscopy to quantify the biodiesel concentration in diesel/biodiesel blends prepared from different feedstocks. Four different blends prepared using biodiesel produced from four refined vegetable oils (canola, sunflower, corn, and soybean) were used in the present investigation. For all samples, the fluorescence spectra were collected between 300 and 800 nm when excited at 260 nm. Our results revealed that the four blends presented a similar emission profile with a maximum at 470 nm. Furthermore, the same fluorescence behavior (emission intensity as a function of biodiesel content) was observed for all blends. Therefore, the results showed that fluorescence-based method for quantifying the biodiesel content in the diesel/biodiesel blends is independent of the refined vegetable oil used in the biodiesel production.

► Fluorescence measurements of diesel and diesel-biodiesel blends were performed.
► Blends were prepared using biodiesel produced from canola, soybean, corn, and sunflower refined oils.
► A similar increase in the fluorescence intensity as a function of biodiesel content was determined for all blends.
► Fluorescence behavior was practically independent of the biodiesel feedstock.