Effect Of Mobile Phase Flow State On Chromatographic Behavior

Radial inhomogeneity is a common problem in liquid chromatography columns.The presence of this inhomogeneity leads to a certain degree of bending and broadening of the target analyte band during the chromatographic process,thereby reducing the overall efficiency of the chromatogram.To this end,this paper combines computational simulation and chromatographic experiments to study the flow state model of the mobile phase of annular flow and multi-channel parallel splitting flow,revealing the inherent laws affecting chromatographic behavior,and providing new solutions for the development of liquid chromatography technology in the future.The research results are as follows:Annular flow:It is found through computational simulation that annular flow has an effect on the chromatographic behavior,the flow state of the annular flow is not only related to its position and size,but also related to the radial inhomogeneity and length of the column;When PR=1.10,the circular flow state of PD=0.8 and PL=O.5 can increase the column efficiency by 1.38 times;when the column length is 240 mm,the annular flow state of PD=0.8 and PL=0.5 can improve the column efficiency by 73.6%.Pr indicates the radial inhomogeneity of the column,PD indicates the ratio of the diameter of the circular shape of the circular flow chromatography to the inner diameter of the column,which is the size parameter of the annular flow state.PL indicates the ratio of the placement height of the circular shape of the circular flow chromatography to the column length,which is the positional parameter of the annular flow state.It has also been found that the annular flow is more suitable for large-scale preparative columns.It was further verified by chromatographic experiments that for a column of 80 mm× 14 mm,the circular flow of PD=0.2 and PL=0.125 can improve the efficiency of the liquid chromatography by 1.4 times.Multi-channel parallel splitting flow:It is found through computational simulation that the multi-channel parallel splitting flow state has an effect on the chromatographic behavior.The size ratio of inner tube and core is the main factor to affect the multi-channel parallel splitting flow state,and the effective radial direction distance of the channels(dv)ratio is a key parameter for characterizing multi-channel parallel splitting flow.Under certain conditions,the smaller dv ratio contributes to the improvement of chromatographic efficiency of multi-channel parallel splitting flow;Under certain radial structural characteristics,there is the best core height,and the radial structure conditions are different,the optimal core height is also different.Under the multi-channel parallel splitting flow state,the media size of the internal channel has the optimal size.For example,for a column of 200mm×20mm,when the dv1/dv2=4:3 and the height of the core is 20 mm,the media size in internal channel is 3 ?m,the column efficiency is the highest,reaching 61.21%.It is further verified by chromatographic experiments that under certain conditions,the multi-channel parallel splitting flow of the mobile phase can improve the column efficiency.The chromatographic behavior of the B-structure of the parallel flow of the two channels is better than the A-structure,which can improve the column efficiency by 21.52%.