Towards microfluidic devices for multi-dimensional separations

The aim of this this work is to explore and study the functionality of 3D-printed devices for application in multi-dimensional separations. In particular, this work focuses on the development of spatial 2D-LC systems. Several aspects are investigated, such as (i) the creation of a homogeneous stationary phase, for example through the incorporation of polymeric monoliths in selective regions in various housings (e.g materials), (ii) establishing homogeneous flows that are confined to the appropriate dimension during each of the separation stages, (iii) maximizing the peak capacity, and (iv) maintaining the integrity of the resulting separations. A novel way to rapidly create prototypes of separation devices may be established through the use of 3D-printing technologies. In this work, 3D-printed channels for the separation of small molecules were successfully developed in-house and a reversed-phase LC (RPLC) separations was described that were achieved by in-situ fabrication of porous polymer monoliths, directly within 3D-printed channels. Also, several aspects of prospective spatial 2D-LC systems were studied, viz. efficient transfer of samples between the two dimensions and the flow behaviour within the device. Focus was on the computational transient and steady-state simulations to study flow velocity and band broadening. In devices intended for multi-dimensional separations, it is critical to confine the flow to the correct dimension and the boundaries between the dimension, with clearly defined zones of different stationary phases for each dimension. Therefore, the implementation of monolithic frits in a two-dimensional separation device were explored and described. The work in this thesis are steps to come closer to achieving a spatial 2D-LC separation in the future