Optimizing design and employing permeability differences to achieve flow confinement in devices for spatial multidimensional liquid chromatography.

In spatial multi-dimensional liquid chromatography (LC) devices the flow of each dimension has to remain in the corresponding region, otherwise the separation efficiency is undermined. Adequate flow-confinement measures are necessary. Here, the use of permeability differences across different compartments of spatial two-dimensional (2D) and three-dimensional (3D) LC devices as a method to guide fluid flow and reduce analyte loss during the first, second- and third-dimension development was investigated with computational fluid dynamics (CFD) simulations. In case of 2DLC devices, it was shown that porous barriers with a permeability on the order of 10 m suffice to keep the total sample spillage from an open D channel under 1%. In case of 3DLC devices, it was shown that flow confinement could be achieved using an open D channel in combination with a highly-permeable monolith (permeability on the order of 10 m) in the second-dimension (D) and a less permeable packing with a permeability on the order of 10 m (e.g. 1 μm particles) in the third-dimension (D). Additionally, the impact of the D flow-distributor has been studied and a novel design, capable of limiting the spillage to the other dimensions to the absolute minimum, is proposed.