The use of Raman spectroscopy for in situ monitoring of lysozyme concentration during crystallization in a hanging drop

Fiber optic Raman spectroscopy combined with a partial least-squares regression model was investigated as a means to monitor lysozyme concentration during crystallization in a hanging drop experiment in real time. Raman spectral features of the buffer and protein were employed to build the regression model. This model was used to calculate the compositional changes within the hanging drop. The use of fibre optic technology coupled with Raman spectroscopy, which is ideal for use with aqueous media, results in a powerful noninvasive probe of the changing environment within the solution. These preliminary findings indicate that solubility as well as supersaturation measurements can be made. (C) 1999 Elsevier Science B.V. All rights reserved.