ASTM D6866
- Also known as
- D6866, biobased carbon test
ASTM D6866 is a standard test method that measures how much of the carbon in a product comes from recent biological sources rather than from fossil fuels, using radiocarbon (carbon-14) analysis. It is the basis for certified biobased content claims.
What is ASTM D6866?
ASTM D6866 is a test standard published by ASTM International for determining the biobased content of a material: the share of its carbon that comes from plants, animals or other recently living sources rather than from petroleum, natural gas or coal.
How the test works
The method relies on radiocarbon. Living things continually take up carbon from the atmosphere, which contains a small, steady proportion of carbon-14, a naturally radioactive form of carbon. Fossil fuels formed millions of years ago, long enough for their carbon-14 to decay away completely. So:
- Carbon from a recent biological source contains carbon-14.
- Carbon from a fossil source contains essentially none.
The laboratory measures the carbon-14 content of a sample, usually by accelerator mass spectrometry, and compares it with a modern reference to calculate the percentage of the carbon that is biobased.
What the result means
The result is the biobased share of the organic carbon in the product. It is not a percentage of total weight, and it says nothing about water, minerals or other inorganic ingredients. A product labeled 100 percent biobased contains no fossil carbon; a product at 50 percent draws half its carbon from each source.
The test also does not measure biodegradability or environmental impact. It answers only where the carbon came from.
Where ASTM D6866 is used
The USDA BioPreferred Program requires ASTM D6866 testing for products that carry the USDA Certified Biobased Product label, and the percentage shown on the label comes from it. The method is also used to verify renewable content claims in fuels, plastics and chemicals.
Frequently asked questions
No. It measures only the source of a product’s carbon. Biodegradability is tested separately, for example under OECD 301.
Carbon-14 decays with a half-life of about 5,700 years. Fossil fuels are millions of years old, so any carbon-14 they once contained has decayed away.
Sources
- ASTM D6866, Standard Test Methods for Determining the Biobased Content of Solid, Liquid, and Gaseous Samples Using Radiocarbon Analysis, ASTM International
- USDA Certified Biobased Product label requirements, USDA BioPreferred Program