Quantitative Determination by ¹⁴C Analysis of the Biological Component in Fuels

Abstract

ABSTRACT. Radiocarbon analysis was performed by liquid scintillation counting (LSC) and accelerator mass spectrometry (AMS) to assess whether the content of biological components in hydrocarbon fuels could be derived. Different fuel mixtures were prepared containing bioethanol, fossil ethanol, and fossil gasoline. The specific 14 C activity of these mixtures was obtained from LSC measurements and directly related to the concentration of carbon originating from the bioethanol (biocarbon). The results were checked via standardized carbon dating procedures and AMS. A good linear correlation exists between the fuel mixture's specific 14 C activity and the concentration of biocarbon. Also, the biocarbon fraction of the fuel mixture (the ratio biocarbon : total carbon) and the normalized fraction of biocarbon (%M) showed good linear correlation. Therefore, both relations provide a possibility to quantitatively determine a fuel's biocarbon content by 14 C analysis. When the sample composition is known (e.g. resolved by gas chromatography-mass spectroscopy [GC-MS] and nuclear magnetic resonance [NMR]), the amount of particular biological components in a fuel sample can be derived subsequently. For mixtures of bioethanol, fossil ethanol, and gasoline with bioethanol contents in the range of 0.5-2% m/m, it was found that errors in the normalized fraction of biocarbon (%M) were in the range of 25-10%, respectively. For samples with a higher bioethanol content (up to pure bioethanol), the errors in %M were <10%. Errors might be larger if substantial changes in the concentration of atmospheric 14 C took place during the growth period of the biofuel feedstock. By taking into account the variation in specific 14 C activity of carbon over the last decades, and by modeling simple tree-growth, it could be illustrated that this effect becomes significant only if the biofuel feedstock stopped growing more than 1 decade ago, e.g. with wood from constructions.

Interlaboratory Variability of Radiocarbon Results Obtained from Blind AMS Analyses on Several Modern Carbon Samples

“…This suggests that volatile liquid fuels may be more difficult to prepare for analysis without incurring significant sample processing errors. If the variability in pMC values noted for the bioethanol are truly due to sample processing errors, then using the direct liquid scintillation counting (LSC) approach for analyzing liquid fuels (Dijs et al 2006;Norton 2009) might reduce the amount of interlaboratory variability for those types of samples, since that method does not involve sample combustions with subsequent processing of CO 2 . However, the interlaboratory repeatability of the direct LSC method has not yet been explored.…”

Determination of biogenic component in liquid fuels by the 14C direct LSC method by using quenching properties of modern liquids for calibration

“…Intensive use of fossil fuels for energy production and transport during 20th century caused an increase of CO 2 concentration in the atmosphere (Dijs et al, 2006). The increase of CO 2 concentration can be slowed down by the use of biogenic materials for energy production and/or transport.…”

Simplified Radiocarbon Analysis Procedure for Measuring the Renewable Diesel Concentration in Diesel Fuel Blends

“…This is known as the direct LSC method since all conventional sample preparation procedures are eliminated, thereby reducing sample preparation time and analytical costs by 90% or more. The direct LSC method has recently been used to analyze gasoline/ethanol fuel blends and appeared to be promising for that application [7,10]. Since no studies have been reported on using that method to analyze other types of liquid fuels, we explored the applicability of the method to renewable diesel measurements.…”