The Design And Study Of Ring Frit Structure In Liquid Chromatograph

Radial heterogeneity of chromatographic column is both ubiquitous and difficult to eliminate in all HPLC columns. Radial heterogeneity causes the broaden of analyte band in the axial direction during the migration. This phenomenon will cause the extension of the peak and even the worse of the peak tailing. In this way, radial heterogeneity reduced the separation performance of the columns. In this study, A new column frit structure termed ring frit was designed to decrease the influence of column radial heterogeneity. This design was implemented to reduce the velocity gradient caused by radial heterogeneity and uniform the flow distribution to optimize the separation performance of columns.Computational Fluid Dynamic method and FLUENT software was employed to evaluate the performance of the ring frit structure. By the simulation of chromatographic process, the working mechanism and the rules of ring frit structure was revealed. More column experiments and chromatographic separation of mixture system experiments were carried to confirm and to evaluate the effect of the ring frit structure.Many achievements were made in this research. Firstly, CFD method by FLUENT software was proved to be a promising tool in the research of chromatographic columns. This method can reveal the detailed chromatographic process inside columns and describe the mechanism theoretically. Secondly, the contributions of ring frit to column efficiency were confirmed by computational fluid dynamics method and real life column experiments. Compared with conventional frit, ring frit structure can decrease the influence of radial heterogeneity on columns. It can equalize flow rate to generate an optimized peak and thus to improve column efficiency. At the same time, the effect of the ring frit structure was found to be connected to the size of the impervious region. Under the study condition, the ring frit with a 50%-80%impervious region was proved to be better than other sizes. Lastly, the effect of ring frit structure is affected by the velocity and the length of columns. The ring frit has a better performance in a longer column when the mobile phase velocity is low. And it has a better performance in a shorter column when the mobile phase velocity is high.