Analysis of biodiesel blend samples collected in the United States in 2008

The quality of B20 (20 vol% biodiesel, 80 vol% petroleum diesel fuel) in the United States was sampled in 2008. Thirty-two samples from retail locations and fleets using B20 were tested against the proposed D7467 B6-B20 specification, which took effect later in 2008. Sixty percent were ±2% (nominally) B20. Twenty-five percent failed the proposed minimum induction period stability of 6 hours; the overall average was 8.4 hours. All B20 samples met proposed specifications for acid value, cetane, and ash. Ion chromatography was used to determine free and total glycerin in B20 blends. Results showed that all the B100 used for blending met D6751 glycerin specifications. Samples were analyzed by multidimensional gas chromatography to determine the B100 feedstock; most was soy-derived; some was animal-derived. The average dissolved water in B20 samples was 130 ppm, 30% higher than the typical saturation level of diesel fuel. Particulate contamination in the B20 was below 20 mg/L in every case but one.