No.8（2013）10.Determination of ETBE contents in red-dyed gasoline by liquid scintillation counting

Shunji Yunoki, Masaaki Saito, Yoshiyasu Nagakawa

  Ethyl tert-butyl ether (ETBE) added in colorless gasoline can be theoretically measured by liquid scintillation counting (LSC), where 14 C is measured to determine the contents of bio-based carbons. However, red fuel dye in gasoline may cause "color quenching" in LSC measurements, which disturbs precise counting of 14 C. In this study we evaluated the effect of removing the red dye on the determination of ETBE contents in simulated gasoline (10% and 25% ETBE in petroleum benzine (E10 and E25)) by LSC. As expected, the red dye caused quenching in LSC, decreasing counting efficiency. This disturbance in LSC could not be completely corrected by the routinely applied external standard method. When E10 and E25 were treated with activated clay at the weight ratio of activated clay to simulated gasoline increased to 0.05, the counting efficiency increased to be similar levels when the dye was absent. On the other hand, the counting efficiency of the colorless simulated gasoline significantly decreased when the weight ratios of activated clay reached 0.2. We concluded that LSC could precisely determine ETBE contents in E10 and E25 by removing the red dye with activated clay at concentrations of 0.05-0.1.

Keywords
Bio-based content, Biofuel, Ethyl tert-butyl ether, Liquid scintillation, Radiocarbon, Gasoline

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