Fused silica capillary tube

All experiments were performed using a capillary LC (liquid chromatography) system constructed from the following devices. The pump was a microfeeder (L.TEX Corporation, Tokyo, Japan) equipped with a 0.5 mL gas-tight syringe (ITO Corporation, Fuji, Japan). A capillary column prepared from a fused-silica capillary tube (100 × 0.32 mm i.d., GL Sciences Inc., Tokyo, Japan), an M-435 micro injection valve (Upchurch Scientific, Oak Harbor, Wash., USA) with injection volume of 0.2 μL, and a UV detector model UV-2075 (JASCO Corporation, Tokyo, Japan) used at a detection wavelength of 210 nm were used. CDS-Lite Ver. 5.0 (LAsoft LTD., Chiba, Japan) was used to process the data. The inlet pressure was monitored by a L.TEX-8150 pressure sensor (L.TEX Corporation).
The separation columns were immersed in a water bath at 25 ± 1°C to maintain a stable temperature throughout the study.
An elemental analysis of the prepared stationary phase was conducted by using a Micro Corder JM10 (J-Science Lab Co., Ltd., Kyoto, Japan). FT-IR spectra of the monoliths before and after reacting with crown ether were taken using a Spectrum 400 FT-IR Spectrometer (PerkinElmer, Waltham, MA, USA) equipped with an all-reflective optics device GladiATR (PIKE Technologies, Madison, WI, USA). The pH was measured using an HM-41 type pH meter (electrode GST-5821C) manufactured by TOA DKK Corporation (Tokyo, Japan).

The reagents employed were of guaranteed grade reagents and were obtained from Wako Pure Chemical Industries (Osaka, Japan), unless otherwise noted. Sodium bromide, sodium iodate, sodium iodide, sodium nitrate, sodium nitrite, sodium thiocyanate, ammonium chloride and benzyltrimethylammonium chloride were obtained from Nacalai Tesque (Kyoto, Japan). 3-(Trimethoxysilyl)propyl methacrylate was obtained from Tokyo Chemical Industry (Tokyo, Japan). Lithium chloride, magnesium chloride hexahydrate and potassium chloride were obtained from Yoneyama Yakuhin Kogyo (Osaka, Japan).
[2-(Methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (zwitterionic monomer) was obtained from Sigma-Aldrich (St. Louis, USA). Ultrapure water was prepared in the laboratory by using a Simplicity UV water purification system (Millipore, MA, USA), and all solutions used in this study were prepared using this ultrapure water. All packing materials were packed in fused-silica capillary tube (100 × 0.32 mm i.d.; GL Sciences, Tokyo, Japan).

In this work, all experiments were conducted by using a capillary LC system constructed by a microfeeder (L.TEX Corporation, Tokyo, Japan) equipped with a gas-tight syringe (0.5 mL; Ito, Fuji, Japan) as a pump, an M-435 micro valve injector (Upchurch Scientific, Oak Harbor, WA, USA) with an injection volume of 0.2 μL, a microcolumn prepared from a fused-silica capillary tube (100 × 0.32 mm i.d.; GL Sciences, Tokyo, Japan), a UV detector (JASCO, Tokyo, Japan) with a wavelength 210 nm, and a data processor (CDS-Lite Ver. 5.0; LA soft, Chiba, Japan). The inlet pressure was monitored by an L.TEX-8150 Pressure Sensor (L.TEX). Separation columns were immersed into a water bath for temperature controlled 20°C throughout the study.