Measurement of temperature and concentration dependences of refractive index of hen-egg-white lysozyme solution

This paper reports the measurement of temperature and concentration dependences of the refractive index of hen-egg-white lysozyme (HEWL) solution, and the temperature dependence of refractive index of the quartz container, which are indispensable for the efforts to measure HEWL concentration of the solution during the processes like crystal growth and dissolution using interferometer. As all of these dependences might be different under different observation wavelengths, temperatures and solution compositions, it is necessary to measure them for specific conditions. In this paper, the desired dependences were measured without knowing the actual value of the refractive index. The measurement method was introduced and the measurement experiments were undertaken at wavelength 780nm. The dependences obtained will be also useful for those studies employing the same wavelength and solution conditions.