Comparing a novel voltammetric method with a standardized method for quality control of biodiesel.

Biodiesel is a strong candidate to replace diesel and has its origin in renewable resources. The guarantee of biodiesel quality is a matter of utmost importance in order to take its place in the global energy matrix. One of the parameters that stand out in the monitoring of its quality is the acid number. The evaluation of this parameter is of paramount importance by considering the raw material used in the production of biodiesel up to its storage, since the presence of free fatty acids leads to the formation of deposits in the injector nozzles. The standardized method in Europe, Brazil and the USA is based on potentiometric titration, using KOH as a base. This method has some drawbacks such as long analysis time, parallel reactions with possible contaminants or additives, etc. Recently, our group proposed a method based on the voltammetric reduction of 2-methyl-1,4-naphthoquinone in the presence of acids. The generated pre-peak current is proportional to the concentration of acids in the medium. This paper reports a comparison of the conventional and our method considering analysis conditions, repeatability, limits of detection and quantification, recovery, selectivity, reproducibility and determination of acidity in various biodiesel samples. [ABSTRACT FROM AUTHOR]