Gravity‐flow open tubular cation chromatography

Abstract

We describe ion chromatography (IC) on open tubular cation exchange columns with a controllable capacity multilayered stationary phase architecture. The columns of relatively large bore (75 lm id) are fabricated by coating fused-silica capillaries with multiple layers of poly(butadiene-maleic acid) (PBMA) copolymer and crosslinking the deposited layers by thermally initiated radical polymerisation. Column capacity increases in a predictable manner with increase in the number of successively coated layers. Gravity flow with a modest head (a 2 m) can provide the desired separations within a reasonable period. We provide a minimalist configuration where no suppression is used, the sample is injected hydrodynamically as in CE, and detection is accomplished by an inexpensive homebuilt contactless conductivity detector or a capacitance to voltage digital converter. A 1 m long 75 lm bore column coated with two layers of PBMA allows gravity-flow open tubular IC to separate four alkali cations in a 10 min with a 1 mM tartaric acid (TA) eluent. Simultaneous separation of alkali and alkaline earth metal cations can be accomplished in less than 25 min using 1.75 mM pyridinedicarboxylic acid as an eluent. Contactless conductometric detection (C 4 D) allows LODs down to 150 nmol/L, corresponding to 30 fmol injections. Analysis of real water samples is demonstrated.

Analytical Conditions and Separation Performance of Capillary Chromatography Based on the Tube Radial Distribution of Aqueous-Organic Mixture Carrier Solvents under Laminar-Flow Conditions

“…13,14 We modified the inner walls with specific functional groups or molecules, such as phenylboronic acid, iminodiacetic acid, and antibodies for capillary chromatography to take advantage of specific interactions between the solutes and the modified walls. [15][16][17][18] Methods for the preparation of open capillary tubes coated with molecularly imprinted polymer 19 and cation exchange polymer 20 have also been reported for use in chromatography. Furthermore, such coating techniques have been applied to fused-silica capillary tubes less than 10 μm in i.d.…”

A thin-layer contactless conductivity cell for detection in flowing liquids

“…A comparison is possible, to a certain degree, for the K + ion which was detected in the present work and in Refs. [7,10]. It can be seen from Table 3 that the thin-layer C 4 D exhibits a substantially wider linear dynamic range than the tubular detectors, the other parameters being rather similar.…”

Use of disposable open tubular ion exchange pre-columns for in-line clean-up of serum and plasma samples prior to capillary electrophoretic analysis of inorganic cations

“…Preparation of poly(butadiene-maleic acid) (PBMA) based OT columns was described previously [18]. A thin layer of PBMA prepolymer mixed with 5% azobisisobutyronitrile (AIBN) was coated onto a 1 m long FS capillary (75 m ID, 375 m OD, Microquartz GmbH, Munich, Germany) and crosslinked at 160 • C for 15 min.…”