Use of kinetic plots for the optimization of the separation time in ultra-high-pressure LC.

The kinetic-plot approach, in which experimental t(0) and N-values are extrapolated to the performance at maximum system pressure by increasing the column length, was validated by coupling 250×3 mm columns packed with 3 μm particles. The extra-column volume introduced by coupling columns could be neglected with respect to the peak volumes. Plate numbers of up to 132,000 were experimentally achieved by coupling four columns.

Automatic column coupling system to operate chromatographic supports closer to their kinetic performance limit and to enhance method development.

A new hardware solution is proposed that allows one to automatically change the length of a chromatographic bed. The setup is based on the serial coupling of chromatographic columns using two rotor-stator valves (with N positions, N + 1 ports). Despite the use of a prototype setup requiring rather long connection tubing, only 9% loss in efficiency is observed for compounds with a retention factor above 4 compared to the efficiency expected on the basis of the individual column results.

A protocol for designing comprehensive two-dimensional liquid chromatography separation systems.

In this paper a protocol is proposed for establishing suitable column dimensions (length and diameters), particle sizes, flow rates, and second-dimension injection volumes (i.e. loop sizes) in comprehensive two-dimensional liquid chromatography (LC x LC).

Comparison of the efficiency of microparticulate and monolithic capillary columns.

A comparison is made between the efficiency of microparticulate capillary columns and silica and polymer-based monolithic capillary columns in the pressure-driven (high-performance liquid chromatography) and electro-driven (capillary electrochromatography) modes. With packed capillary columns similar plate heights are possible as with conventional packed columns. However, a large variation is observed in the plate heights for individual columns.