title: Using near-infrared overtone regions to determine biodiesel content and adulteration of diesel/biodiesel blends with vegetable oils.
abstract: This work evaluates the use of near-infrared (NIR) overtone regions to determine biodiesel content, as well potential adulteration with vegetable oil, in diesel/biodiesel blends. For this purpose, NIR spectra (12,000-6300 cm(-1)) were obtained using three different optical path lengths: 10 mm, 20 mm and 50 mm. Two strategies of regression with variable selection were evaluated: partial least squares (PLS) with significant regression coefficients selected by Jack-Knife algorithm (PLS/JK) and multiple linear regression (MLR) with wavenumber selection by successive projections algorithm (MLR/SPA). For comparison, the results obtained by using PLS full-spectrum models are also presented. In addition, the performance of models using NIR (1.0 mm optical path length, 9000-4000 cm(-1)) and MIR (UATR - universal attenuated total reflectance, 4000-650 cm(-1)) spectral regions was also investigated. The results demonstrated the potential of overtone regions with MLR/SPA regression strategy to determine biodiesel content in diesel/biodiesel blends, considering the possible presence of raw oil as a contaminant. This strategy is simple, fast and uses a fewer number of spectral variables. Considering this, the overtone regions can be useful to develop low cost instruments for quality control of diesel/biodiesel blends, considering the lower cost of optical components for this spectral region.
authors.affiliation: Departamento de Química, Universidade Federal da Paraíba, João Pessoa, Brazil.
authors.forename: Fernanda Vera Cruz
authors.initials: FV
authors.lastname: de Vasconcelos
authors.forename: Paulo Fernandes Barbosa
authors.initials: PF
authors.lastname: de Souza
authors.forename: Maria Fernanda
authors.initials: MF
authors.lastname: Pimentel
authors.forename: Márcio José Coelho
authors.initials: MJ
authors.lastname: Pontes
authors.forename: Claudete Fernandes
authors.initials: CF
authors.lastname: Pereira
mesh_terms: D000465:Algorithms; D056804:Biofuels / Q000032:analysis*; D016018:Least-Squares Analysis; D016014:Linear Models; D010938:Plant Oils / Q000032:analysis*; D019265:Spectroscopy, Near-Infrared
chemical_list: D056804:Biofuels; D010938:Plant Oils