State of the art in miniaturized separation techniques

Abstract

Miniaturized separation techniques have become very attractive recently because they offer a number of advantages over classic ones, for example, reduced chemicals consumption, separation improvement, and better sensitivity. It is also very important that they require minute samples, which is very often of primary importance in the environmental or biomedical sciences. In general, miniaturized systems that are being developed currently are divided into column and chip ones. For best performance of the separation microsystem, it must be properly designed in the terms of volumes and shapes of the parts it consists of. Theoretical considerations present this problem. As column systems are better known and understood the microcolumns are more frequently developed. Current works are focused on the preparation of unified columns that can be used in various techniques - for example, in micro-HPLC and CEC. Because of problems occurring in packed capillary column preparation and utilization, monolithic (rod) columns are developed to overcome the problems of inhomogeneity of packing or bubble formation under electroosmotic flow conditions. The requirements of minute sample analysis have been resolved by the construction of chip devices originating from total analysis system (TAS). Such systems are primarily designed for zone electrophoresis separations; however, micellar electrokinetic chromatography, gel chromatography, electrochromatography, or liquid chromatography can be performed using a chip device. In this article the most important trends in miniaturization of the separation systems are discussed, including theory, system preparation, and performance as well as exemplary applications.