Analysis of biodiesel-diesel blends using ultrafast gas chromatography (UFGC) and chemometric methods: Extending ASTM D7798 to biodiesel

Abstract Ultrafast gas chromatography (UFGC) along with supervised and unsupervised chemometric methods were utilized for evaluation of biodiesel-diesel blended fuels. A variety of biodiesel feedstocks (soybean, tallow, canola, safflower, sunflower, camelina, flaxseed, etc.) and concentrations (1–20%) were evaluated. The method, which uses a short nonpolar column, falls within ASTM D7798 requirements for diesel and extends the method to include biodiesel-diesel blended fuels. Using Principal Components Analysis (PCA), samples clustered based on concentration and diesel type, and differences in plant and animal feedstocks were apparent. Biodiesel concentration was accurately assessed using Partial Least Squares (PLS) on a training set for B0–B20, while predictions were made with some success on a set of commercial and lab unknowns. k Nearest Neighbors (kNN) was used to describe and predict concentration, plant versus animal feedstock, and to identify biodiesel blends. The combination of chemometric methods alongside UFGC proves an effective and fast technique for the analysis of biodiesel source and composition in biodiesel-diesel blended fuels.