The application of high pressures in ion chromatography (IC) can significantly improve the efficiency and reduce the analysis time. In this work, the kinetic-performance limits of capillary IC columns with inner diameters of 400 µm packed with 4 and 7 µm super macroporous anion-exchange particles were investigated employing a capillary ion-exchange instrument allowing column pressures up to 34MPa.

Plate heights below 10 µm could be realized in isocratic mode using capillary columns packed with 4 µm particles. Compared to conventional IC using 7 µm particle-packed columns and pressures up to 20 MPa a 40% improvement in plate number could be achieved when working at the kinetic performance limits at 34 MPa and using columns packed with 4 µm particles. The performance limits were also characterized in gradient mode. Using a linear gradient significant broadening was observed with increasing retention factor. Therefore the use of concave gradients were explored to establish the performance limits at maximum operating pressure. The potential of high-efficiency capillary IC is demonstrated with high-pressure gradient IC separations using coupled columns.

In a next step to system miniaturization we are focusing on the development of a portable ion analyzer, composed of different substrate layers, each with their own channel layout and functionality. In a first step, a prototype on-chip microfluidic membrane suppressor has been developed and characterized as a stand-alone module and its capabilities and limitations will be discussed.