Automated Physical Property Measurements from Calibration to Data Analysis: Microfluidic Platform for Liquid–Liquid Equilibrium Using Raman Microspectroscopy

Abstract

The combination of microfluidics and Raman microspectroscopy has proven to reduce the time and amount of materials required to determine liquid–liquid equilibrium (LLE) data. Until now, the experiments have been conducted manually. However, many applications have shown that the highest efficiency and user independence can be reached by automation. Therefore, we developed an automated setup and workflow from calibration to data analysis for the determination of liquid–liquid equilibrium data using Raman microspectroscopy and a microfluidic platform. Pure components are premixed online using a micromixer, resulting in a closed system with the additional advantage of avoiding potential losses of volatile components. In the automated setup, one experiment generates several data points for calibration and LLE data measurements. The automated setup and workflow are successfully validated with respect to both the integrated calibration and the LLE measurements. For this purpose, we studied two ternary systems (cyclohexane–toluene–methanol and n-heptane–acetonitrile–ethanol) at T = 298.15 K. The presented automated setup is shown to be both accurate and efficient with respect to time and materials for the determination of LLE data.