|Bio and fossil ratio determination from 2 uL of fuel|
|In contrast to LSC technique, discoloration of the sample does not hinder the measurement|
|Placing only one drop of the sample in to a glass tube along with MnO2 reagent|
|Cooling at -70°C and evacuation|
|Sealed tube combustion at 550°C|
|CO2 purifying and graphitization|
The European Union, aiming more effective environmental preservation actions, has set the goal of reducing of the contribution of fossil fuels in several economic sectors. In road transport, one of the applied principles is admixing of certain ratio of biogenic, i.e. renewable components to fossil fuels. Nevertheless, some of the additive biogenic compounds are originally presented in the fossil energy sources as well; hence, their extraction is considerably circumstantial. Therefore, the significance of 14C-based methods has increased in investigations relating to the quantification of the fraction of biogenic components in fuels. The cosmogenic radiocarbon content of fossil materials has decayed long time ago, while the similar biogenic additives are of well determined radiocarbon content (approximately 226 Bq/ kg C) which is identical with that of the atmosphere; this assumption make the differentiation of the fractions possible.
Radiocarbon content of fuels can be directly measured by liquid scintillation method, however due to the discoloration of samples, as a big drawback, the chemical quench effect can be significant, furthermore, measurements require a lot of time as well. In favour of the simplified measurement, a new AMS preparation method was developed at HEKAL. In course of this method one drop of the fuel is placed in a glass tube along with MnO2 oxidizer reagent, this sample then is combusted off-line in a muffle oven and, eventually, the evolved CO2 is purified using a high vacuum system. The reliability, efficiency, reproducibility, accuracy of the developed method was tested on samples with diverse biogenic and fossil fractions.