In Situ Analysis of Lactose Crystal in Solution through Slurry Flow Cell X-Ray Diffraction

To realize the in situ study of polycrystals, X-ray diffraction (XRD) with the sample stage of slurry flow cell is used to study the crystal state of the lactose in solution directly. The influence of absolute ethyl alcohol and pH on the crystallization of lactose is investigated by the slurry flow cell. As the lactose is dispersed into absolute ethyl alcohol, the equilibrium of crystal is reconstructed, which induces crystal dissolution, nucleation formation, and crystal growth, then results in the difference of lactose diffractogram between the absolute ethyl alcohol solution and powder state. Peaks become sharper and higher in absolute ethyl alcohol than those of absolute ethyl alcohol with pH 3.5, which suggests that the crystal growth is easier in ethyl alcohol solution. The investigation of absolute ethyl alcohol and pH on the lactose crystals proves the capability of the XRD technique for in situ crystallization study.