Fused-silica capillaries with photopolymer components

Abstract

A separation column is provided with a photopolymer component which, when irradiated, causes controlled porosity polymerization. A particularly preferred embodiment is wherein the separation medium is retained by a photopolymer frit, which can be reliably and reproducibly generated with controlled porosity.

Description

[0001] 1. Field of the Invention[0002] This invention generally relates to separation columns, particularly capillaries useful in capillary zone electrophoresis, including capillary electrochromatography, and more particularly to separation columns that includes a photopolymer component. This photopolymer component may be in the form of a frit.[0003] 2. Description of Related Art[0004] Over the past decade, capillary zone electrophoresis (CZE), with its high peak capacity (i.e., the number of peaks separated per unit time), has developed into a powerful and widely used technique for separating ionic species by their electrophoretic mobilities. The lack of selectivity for uncharged analytes in CZE, however, has remained more problematic. Several methods have been developed, such as micellar electrokinetic chromatography (MEKC), to help overcome this problem by providing a pseudostationary phase in which uncharged compounds can be separated. The application of methods such as MEKC is ...

AI Technical Summary

Problems solved by technology

The lack of selectivity for uncharged analytes in CZE, however, has remained more problematic.

The application of methods such as MEKC is limited because of the restricted number of pseudostationary phases that can be employed in this technique.

Although systematic studies regarding the effects of the frits on the performance of such capillaries have not been reported, it is thought that these frits may degrade the efficiencies of these capillary columns.

Capillary columns prepared in this manner, however, suffer from low retention and low sample capacities as well as long preparation times. An alternative method for the preparation of open tubular capillary columns uses monolithic packing technology.

This approach has several disadvantages, including (1) difficulty in generating the frit reliably and reproducibly, (2) alteration of the characteristics of the stationary phase within the frit itself, (3) difficulty in controlling the porosity of the frit, (4) weakness of the capillary at the location of the frit, (5) band broadening caused by the frit, (6) bubble formation and adsorption of polar analytes on the frit.

These problems can directly affect the column performance and column-to-column reproducibility.

This results in a short total frit preparation time, and avoids the use of elevated temperatures.

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