Towards ultra-high peak capacities and peak-production rates using spatial three-dimensional liquid chromatography. 
In order to successfully tackle the truly complex separation problems arising from areas such as proteomics research, the development of ultra-efficient and fast separation technology is required.  In spatial three-dimensional chromatography, components are separated in the space domain with each peak being characterized by its coordinates in a three-dimensional separation body.  Spatial three-dimensional (3D-)LC has the potential to offer unprecedented resolving power when orthogonal retention mechanisms are applied, since the total peak capacity is the product of the three individual peak capacities.  Due to parallel developments during the second- and third-dimension separations, the analysis time is greatly reduced compared to a coupled-column multi-dimensional LC approach.  This communication discusses the different design aspects to create a microfluidic chip for spatial 3D-LC.  The use of physical barriers to confine the flow between the individual developments, and flow control by the use of (2)D and (3)D flow distributors is discussed.  Furthermore, the in situ synthesis of monolithic stationary phases is demonstrated.  Finally, the potential performance of a spatial 3D-LC systems is compared with the performance obtained with state-of-the-art 1D-LC and (coupled-column) 2D-LC approaches via a Pareto-optimization approach.  The proposed microfluidic device for 3D-LC featuring 16 (2)D channels and 256 (3)D channels can potentially yield a peak capacity of 8000 in a total analysis time of 10 minutes.