EU sustainability policies are placing increasing requirements on manufacturers to document the origin of their raw materials. The EU Emissions Trading System (ETS), for example, requires industrial installations and waste incineration plants that use mixed fuels to determine the biomass fraction of their CO2 emissions, while the EU Packaging and Packaging Waste Regulation (PPWR) requires biobased content claims on packaging labels to be scientifically substantiated. As biobased materials can be chemically identical to their petroleum-based counterparts, identifying their origin is only possible with advanced analytical techniques, such as the radiocarbon method.
Biobased content measurement with the radiocarbon method
One of the most accurate ways to determine a material's biobased versus petroleum-based composition is to analyze its carbon content. Carbon originating from biobased sources such as plants is radioactive, whereas carbon originating from fossil sources is not. The proportion of radioactive carbon in the sample can thus be used to determine its biobased content.
The radioactive carbon-14 (14C) isotope in organic materials can be measured using accelerator mass spectrometry (AMS). This method is commonly used for radiocarbon dating to assess the age of organic material, but it can also be used to evaluate what proportion of the carbon in a material originates from renewable biomass and what proportion from fossil sources.
Interpreting the analysis results
The amount of biobased carbon in the material can be expressed against total organic carbon (TOC) or total carbon (TC). If the sample contains a significant amount of inorganic carbon (which is neither biomass- nor petroleum-based), this will reduce the apparent biobased fraction when expressed against TC.
To take an example: if all organic carbon in a material is biomass-based, the biobased fraction of total organic carbon is 100%. However, if the same material also contains inorganic carbon, for example in the form of carbonates or carbonic acid, the biobased fraction of total carbon will be less than 100%. This makes it important to specify which basis was used when reporting biobased carbon content.
In most cases, biobased carbon content is determined as a fraction of total organic carbon, as this provides the most meaningful result when the goal is to distinguish carbon of renewable origin from carbon of fossil origin.
Evaluating the biobased content of the final product
It is important to note that biobased carbon content refers only to the fraction of carbon originating from renewable sources, not to the proportion of biobased material in the product as a whole. It is thus only an indirect measure of how biobased the final product is.
To assess what proportion of the product as a whole originates from renewable sources, the total amount of carbon in the product must be known. By comparing the biobased carbon fraction against the product's total carbon content, it is possible to estimate what share of the final product is derived from biomass.
Standard methods for biobased content measurement
There are several internationally recognized standard methods for biobased content analysis:
ASTM D6866 is the most commonly applied method. It can be used to determine the biobased carbon content of solids and liquids against both TOC and TC. Gases can also be analyzed, but the results are always expressed against TC.
ISO 16620-2 can also be used to determine the biobased carbon content in relation to both TOC and TC. The method was specifically developed for monomers, polymers, and plastic products.
The AMS method described in EN 16640 is technically similar to ISO 16620-2, but the standard also specifies a liquid scintillation counting (LSC) method as a normative alternative for radiocarbon measurement. Biobased carbon content is expressed in relation to TC or the total mass of the sample.
In contrast to the other methods, EN 16785-1 is used to determine the overall biobased content of the sample rather than just the biobased carbon content. However, as the method is based on comparing the measured elemental composition (C, H, N, O) and biobased content with declared values, it requires prior knowledge of sample composition and cannot be used for independent third-party testing of products with an unknown composition.
Measurlabs offers testing with all the methods described above. Our customers use these measurements for a range of applications, from determining the biobased content of plastics to calculating the precise biomass fraction of solid recovered fuel and other mixed fuels for emissions reporting under the EU Emissions Trading System.
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