Terahertz Time-domain attenuated total reflection spectroscopy using flow-through method for continuous analysis of dehydration process

In the present paper, we present a novel process monitoring method for the dehydration of ethanol, based on the terahertz time-domain total attenuated reflection spectroscopy (THz-ATR) system, which can be used for measurement of the optical constant of liquids circulating over the ATR surface. Our results indicate a close relationship between the moisture content in ethanol and the refractive index in the THz range. The proposed system successfully evaluates the dehydration of ethanol rapidly and non-destructively. This method is expected to contribute to real-time measurements of chemical reactions for quality control in pharmaceutical manufacturing.