Electrolytic Conductivity as a Quality Indicator for Bioethanol

We present results of the European Metrology Research Project on the SI traceability of electrolytic conductivity measurements in bioethanol. As a first step to this aim secondary conductivity measurements have been performed to characterize reproducibility, stability, measurement uncertainty and the significance of the measurement results. The relative standard measurement uncertainty is of the order 0.3%, while inter-laboratory reproducibility is around 6.9%. The measured conductivities of two samples from different sources show a relative difference of around 30%. These results show that conductivity is an appropriate quality indicator for bioethanol. However, it also demonstrates that inter-laboratory reproducibility has to be improved, in particular with respect to SI traceability.