Interferometry measurement of protein concentration evolution during crystallization and dissolution with improved reliability and versatility

Interferometry is a widely used technique for real-time monitoring of concentration variation during processes in a solution like crystal growth and dissolution. This paper reports a protein concentration measurement system using a conventional Mach-Zehnder interferometer that allows monitoring the time course evolution of the protein concentration distribution during the processes of crystallization or dissolution. The demonstrated method showed improved reliability and versatility in that it (1) enables measurements under versatile temperature conditions and (2) eliminates the unpredictable errors caused by the environmental disturbances. The measurement system described in this paper can also be applied in measurements in other solution systems.