Spectrophotometric and Chemometric Determination of the ASTM Color of Automotive Diesel

• Published in: Energy & fuels 2009-04, Vol.23 (4), p.2136-2142
• Main Authors: Corgozinho, Camila Nunes Costa, Carvalho, Mariana Machado de Oliveira, Barbeira, Paulo Jorge Sanches
• Format: Article
• Language: English
• Subjects: Fossil Fuels
• ISSN: 0887-0624; 1520-5029
• DOI: 10.1021/ef801019s

An important quality standard to be examined is the color of diesels, given the fact that consumers tend to relate a dark colored fuel to low quality fuel, where the dark color comes from the fuels aging. This aging process occurs due to the auto-oxidation of olefins, leading to the formation of soluble and insoluble sediments that can cause crusts inside the engine or clogging of the fuel injection system, preventing the well functioning of the engine. The ASTM 1500 used to determine the diesel color is rather subjective and is only applied to diesel samples that do not contain any type of dye. Having said that, in Brazil the color of a significant fraction of the samples cannot be determined because of the red dye that is added to the diesel from the interior part of the country, this is done in order to differentiate it from the metropolitan diesel with a lower level of sulfur. The methodology proposed in this paper joined partial least-squares regression (PLS) with spectrophotometry of molecular absorption enabling the determination of the ASTM color of diesel oil in the 0 to 6.5 range, including samples with dye added, thus excluding the subjective character and presenting higher precision than the ASTM 1500 method with excellent accuracy.