Exploitation of novel calibration strategies, digital images and flow analysis for biodiesel quality control

Abstract

Biodiesel is produced from renewable sources, such as vegetable oils or animal fats, which cause lower impact on the emission of greenhouse gases. In Brazil, this biofuel is commercialized as blends with diesel in the amount of 10% (v/v) since March 2018. Because of the high demand for biodiesel and the variety of raw materials used for its production, simple, fast, and reliable analytical procedures are required for quality control. However, most official methods are time-consuming and require high amounts of toxic solvents. On the other hand, alternative procedures are often prone to matrix effects. In this context, this project proposes the evaluation of different analytical strategies, involving novel alternatives for calibration, exploitation of digital images and flow analysis for the development of simpler and fast procedures, which should be suitable for in situ analyses and to circumvent matrix effects. Based on digital images and colorimetric reactions, it is proposed the development of a paper-based spot test to quantify biodiesel in blends with diesel, and differentiation maps involving the main parameters for biodiesel quality control. These alternatives ought to minimize the amounts of reagents and solvents and show characteristics suitable for in situ analysis. With the same purpose, it is proposed the development of a flow-based spectrophotometric procedure by exploiting the lab-in-syringe approach to quantify methanol residues in biodiesel. Calibration strategies (especially multi-energy calibration) will be investigated to circumvent matrix effects in the determination of iodine value, free glycerol, and water content in biodiesel samples from different sources. The analytical performance will be critically evaluated by comparison with those obtained in the reference procedures. (AU)