Biodiesel SRM Development

The NIST Analytical Chemistry Division has collaborated with the Brazil National Institute of Metrology, Standardization and Industrial Quality (INMETRO) on the development of the certified reference materials (CRMs) for biofuels, specifically bioethanol and biodiesel materials. NIST led the development of two biodiesel SRMs, one prepared from soy and one prepared from animal fat, and INMETRO led the development of a bioethanol CRM.

Biodiesel is an alternative fuel produced by the transesterification of triglycerides of vegetable oils or animal fat with methanol to form the fatty acid methyl esters (FAMEs). Because some of the by-products, if not removed, can cause engine problems, it is important to have reliable measurements for glycerol, mono- and diacylglycerols, unreacted triglycerides, and fatty acids. The biodiesel industry within the U.S. is growing rapidly, and the biodiesel industry needs reference materials to benchmark the measurements not only of the fatty acids and glycerins but also for sodium, potassium, calcium, magnesium, sulfur, phosphorous, moisture, and density. To meet this need, NIST has developed two biodiesel SRMs, one produced from soybeans (SRM 2772) and one produced primarily from white grease and pork lard (SRM 2773).

The soy-based and animal-based biodiesel materials were obtained from commercial producers and subsampled into 10-mL ampoules that had been flushed with argon. NIST identified the critical chemical and physical properties to measure in the candidate biodiesel SRMs including FAMEs, glycerol content (free and total), glyceride content (mono, di- and triglycerides), methanol and ethanol content, elemental content (sulfur, phosphorus, alkali and alkaline metals, water content, viscosity, density, and acid number. Both NIST and INMETRO provided measurements on the two biodiesel SRMs for as many of these chemical and physical properties as possible. 

Major Accomplishments:

• Developed two biodiesel reference materials, SRM 2772 B100 Biodiesel (Soy-based) and SRM 2773 B100 Biodiesel (Animal-based) with values assigned for key chemical and physical properties