Functionalized polyolefin capillaries for open tubular ion chromatography

Abstract

Open tubular capillary columns for liquid and ion chromatography, based upon an ionically impermeable polyolefin capillary having a bore with a sulfonate-group- or amine-group-functionalized internalsurface. The capillary columns may include a coating of ion exchanging nanoparticles electrostatically bound to the functionalized internal surface. The capillary columns may be made by exposing the interior surface to a sulfonating reagent comprising chlorosulfonic acid (CIS03H), preferably from 85 wt% to 95 wt% chlorosulfonic acid at a process temperature of 20 to 25 DEG C. The interior surfacemay be subsequently exposed to an asymmetrical diamine to form a sulfonic mid-linkage to the diamine, i.e., to form a sulfonamide-linked, amine-group-functionalized internal surface. The coating may be provided by subsequently exposing the interior surface to an aqueous suspension of ion exchanging nanoparticles to electrostatically bond the ion exchanging nanoparticles to the functionalized internal surface.

Description

[0001] governmental support [0002] The present invention was completed under government funding under the grant number NNX11AO76G granted by the National Aeronautics and Space Administration (NASA). The government has certain rights in this invention. Background technique [0003] In the chromatographic system, the separation column can be considered as the most important functional element in the system. Among the various monolithic, packed and open-tube (OT) column options used in liquid / ion chromatography (the latter type requires the least pressure), it allows the use of simple and easily miniaturized pneumatic pumping components. A recent review specifically describes the preparation and application trends of open-tube (OT) capillary columns in separation science [1], but most reported work involves the use of fused silica capillaries, which are incompatible with extreme pH values. In particular, anion exchanger (AEX) coated quartz capillaries have previously been used in ...

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Problems solved by technology

A recent review specifically addresses trends in the preparation and application of open-tube (OT) capillary columns in separation science [1], but most of the reported work involves the use of fused silica capillaries, which are incompatible with extreme pH values

In particular, anion exchanger (AEX)-coated quartz capillaries have previously been used in single-column mode with mildly alkaline or neutral pH eluents [2], but such materials do not interact with surface silanol (-SiOH) Electrostatic attachment of functional groups is not stable in the presence of high concentrations of strong bases (e.g. 50 mM NaOH) for long periods of time, therefore, the use of AEX functionalized quartz capillaries is usually limited to applications that do not require extreme pH values ​​[3,4]

Although polymethylmethacrylate (PMMA) capillaries are known to be significantly more stable than quartz in strong bases [5,6], and have surface carboxylates that can electrostatically bind AEX materials more strongly than the weaker silanol groups of fused silica capillaries Ester (-COOH) functional group, but the applicant found that the attachment of AEX latex and PMMA will gradually lose in the long-term about greater than 5 millimolar concentration (mM) hydroxide

Moreover, none of the above materials allow cation exchanger (CEX) latex particles to attach to the surface of such capillaries, because CEX latex requires a positive surface charge to attach to the capillary surface, and neither fused silica capillaries nor PMMA capillaries have modified the capillary surface. Provides a pH-stable platform for the introduction of positive surface charges

Therefore, these matrices are not suitable for use in isocratic or gradient-suppressed ion chromatography applications

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