Open-Bio - Deliverable 3.2: Evaluation of applicable techniques for the determination of the bio-based content

This report presents the comparison between different methods for the bio-based content determination. Radiocarbon method supplemented by elemental analysis (EN 16785-1) is the standardized method used for the determination of bio-based carbon content and total bio-based content. Application of EN 16785-1 to a certain product results in a fixed number for the bio-based content of the product, describing which fraction of the product originates from biomass. This report discusses a possibility to use stable isotope analysis for the determination of total bio-based content. Sun lotions as a final product and all its constituents were chosen as test product to evaluate the possibility of using stable isotope techniques for the bio-based content determination. The results of the investigations indicate that neither stable isotope analysis of the carbon isotope (d13C) alone, nor stable isotope analysis of carbon, hydrogen and oxygen isotopes (d13C, d2H and d18O) combined cannot be conclusive with respect for the determination of the bio-based content in the selected product and therefore cannot be compared with the bio-based carbon content determined by the radiocarbon method. In the case of the selected product, d13C results of all components and also of the final prod-uct fell into the range of d13C values that are known for C3 plants (from -33 to -20) that could indicate that the material can possibly be produced from C3 plants. However, since the d13C values derived from fossil feedstock materials are in the same range as for C3 plants, then based only on the d13C analysis it cannot be even qualitatively assured whether the ma-terial has a bio-based or fossil origin. It shall be noted here, that such qualitative conclusion would be possible with a higher confidence if d13C range of the measured product and its components corresponded to C4 plants, since there is a clear distinction between the d13C values in C4 plants (from -14 to -9) and fossil feedstock derived materials. But also for materials when it is known that they are produced from C4 plants, to quantify the result to make it comparable with the bio-based content obtained by radiocarbon analysis methods, remains unclear at the current stage of the research. However, probably stable isotopes can be used for certain product categories where one can observe the correlation between d13C and carbon-14, in order to make reliable bio-based content estimations. Nevertheless, despite that stable isotope analysis cannot be used to obtain a certain number for the bio-based content of a product, multiple stable isotopes analysis is widely used to obtain some indications on the geographical origin of the materials and or feed stock. In the food industry authenticity analysis is used to allow distinction between synthetic and natural products. However, these aspects are beyond the scope of the current report. To conclude, in order to determine the bio-based content of a product, the radiocarbon method supplemented by the elemental analysis remains to be the most studied and the most accurate. The limitation of this method is that it cannot provide information on the bio-based content for random products and for products that do not contain carbon. For such products, there is a suggestion to use 3H isotope of hydrogen that is also radioactive. Currently there is no standardized methodology developed for the use of 3H analysis for the bio-based content determination. This subject still demands more research.