Two-dimensional insertable separation tool (TWIST) for flow confinement in spatial separations

Spatial comprehensive two-dimensional liquid chromatography (^xLC×^xLC) may be an efficient approach to achieve high peak capacities in relatively short analysis times, thanks to parallel second-dimension separations [1,2]. A key issue to reach the potential of ^xLC×^xLC is to achieve adequate flow control and confinement of the analytes to the desired regions, i.e. confinement in the first-dimension direction and subsequently homogeneous flow in the second dimension. To achieve these goals we propose the TWIST concept (TWo-dimensional Insertable Separation Tool), a modular device that includes an internal first-dimension (¹D) part that is cylindrical and rotatable. This internal part features a series of through-holes, each of which is perpendicular to the direction of the ¹D flow. The internal part is inserted in the cylindrical casing of the external part. The internal diameter of the casing is marginally larger than the external diameter of the internal part. The external part also comprises a flow distributor and second-dimension (²D) channels. During the ¹D injection and development, the channel is placed in a position where the through-holes are facing the wall of the external part, such that the liquid remains confined within the ¹D channel. Thereafter, to realize the transfer to the second dimension (²D injection), the ¹D channel is rotated, so that the holes of the internal part are aligned with the holes on the external part, allowing a transversal flow of the ²D mobile phase from the distributor through the ¹D channel and eventually into the ²D area.