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^-12 m² suffice to keep the total sample spillage from an open ¹D channel under 1 In case of 3DLC devices, it was shown that flow confinement could be achieved using an open ¹D channel in combination with a highly-permeable monolith (permeability on the order of 10^-12 m²⁾ in the second-dimension (²D) and a less permeable packing with a permeability on the order of 10^-15 m² (e.g. 1 μm particles) in the third-dimension (³D). Additionally, the impact of the ³D flow-distributor has been studied and a novel design, capable of limiting the spillage to the other dimensions to the absolute minimum, is proposed.