Design and implementation of an array of micro-electrochemical detectors for two-dimensional liquid chromatography—Proof of principle

Experimental verification of some theoretical considerations on preparative separation with orthogonal pressurised planar electrochromatography

This paper reports for the first time the coupling of a two-dimensional separation technique known as orthogonal pressurised planar electrochromatography (OPPEC) with on-line UV/VIS detection. It establishes the efficiency characteristic of a planar column used in OPPEC. The studies show that in OPPEC, all separation steps (mixture introduction, separation, and detection) can run successfully as non-separate operation, much like in HPLC, and the planar column has itself good efficiency, ensuring a relatively low plate height value. In its use, some findings of the previously proposed theoretical model concerning optimisation of preparative separation of components with the same electrophoretic mobility are verified - showing that there is a good agreement between theory and experiment. The paper also demonstrates by means of a specific example of separation of a post-reaction mixture obtained after synthesis of valine diastereomers that OPPEC can be a powerful tool used in preparative separation in that it can achieve much higher separation productivity and significantly lower eluent consumption than when using column chromatography techniques.

Construction and initial evaluation of an apparatus for spatial comprehensive two-dimensional liquid-phase separations

Spatial comprehensive two-dimensional chromatography is discussed as a potentially alternative to the conventional column-based approach. In "spatial" separations each analyte ends up in a specific location, rather than being eluted at a specific time. Ultimately, higher peak-capacity-production rates (peak capacity per unit time) may be attained by spatial two- and three-dimensional separations. While low-pressure planar chromatography is well developed, the high-pressure equivalent is still in its infancy. We discuss the requirements for a device for high-pressure spatial two-dimensional chromatography and we describe a possible design. A prototype instrument has been constructed in-house. The preparation of a polymer monolithic separation body and a valve configuration that allows manual sample injection are described. Initial tests of this study included the investigation of the homogeneity of the monolith and the flow profile through the separation body. Furthermore, in order to evaluate the current chromatographic performance of the device, a mixture of dyes was separated in one dimension within 30 s.