Quantitative analysis of biodiesel in diesel fuel by ultraviolet-visible spectroscopy

A preliminary methodology for the determination of biodiesel content in commercial diesel fuel by ultraviolet and visible absorption spectroscopy (UV-Vis) was developed, with the aim of exploring its potential application in optical sensors for monitoring the diesel/biodiesel mixtures in heavy vehicles. Absorbance of visible light between 400 nm and 500 nm showed a linear response of the optical signal as a function of the biodiesel content for the investigated volume concentration range of biodiesel (varying from 0 % to 20 %). Multivariate analysis was used to validate the construction of different calibration curves, differentiated by the origin of feedstocks for the starting pure biodiesel and diesel components, and to determine the optimal wavenumber for performing ordinary linear regression. A narrow range of the visible spectrum around 450 nm provided the best coefficient of correlation for all calibration curves. The effects of the supplier of base biodiesel and diesel components used to obtain the calibration curves on the predictions of the univariate model were also assessed.