Ester content evaluation in biodiesel from animal fats and lauric oils

• Published in: European journal of lipid science and technology 2006-04, Vol.108 (4), p.309-314
• Main Authors: Schober, Sigurd, Seidl, Ingrid, Mittelbach, Martin
• Format: Article
• Language: English
• Subjects: Biodiesel; Biological and medical sciences; ester content; Fat industries; Food industries; Fundamental and applied biological sciences. Psychology; gas chromatography; heptadecanoic acid
• ISSN: 1438-7697; 1438-9312
• DOI: 10.1002/ejlt.200500324

A modified method for the determination of ester contents of biodiesel based on EN 14103 has been developed. The method includes natural contents of heptadecanoic acid ester, which are found in animal fats and interfere with the standard method, into the calculation of ester content values. As a result, biodiesel samples prepared from waste animal fats and oils showed an increase in ester content between 2 and 7 wt‐% compared to values measured according to EN 14103. Furthermore, modifications of the GC temperature program made it possible to include also short‐chain fatty acid esters C8–C12, which can be found in coconut and palm kernel oil, into the calculation. Measurements showed that the ester content of such biodiesel differs by more than 40 wt‐% compared to EN 14103 determinations. However, also the stability of the internal standard solution methyl heptadecanoate influences the values of ester content. It can be demonstrated that after a period of 7 days, an ester content decrease of about 2 wt‐% can be observed. Therefore, the use of almost freshly prepared standard solutions should be recommended.