On-Line Gas-Free Electrodialytic Eluent Generator for Capillary Ion Chromatography

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• 作者：Bingcheng Yang ; Masaki Takeuchi ; Purnendu K. Dasgupta
• 刊名：Analytical Chemistry
• 出版年：2008
• 出版时间：January 1, 2008
• 年：2008
• 卷：80
• 期：1
• 页码：40 - 47
• 全文大小：260K
• 年卷期：v.80,no.1(January 1, 2008)
• ISSN：1520-6882

文摘

Both low- and high-pressure, gas-free, capillary-scaleelectrodialytic generators for eluents in ion chromatography are described. While the low-pressure devices relyon planar or tubular membranes, the high-pressuredevices rely on ion-exchange beads used both as one-wayionic gates and as ball-on-seat valves to provide sealing.The high-pressure device is easily implemented in theform of a commercial cross fitting and can withstand atleast 1400 psi. By design these devices do not producegas in the eluent channel; hence, it is not necessary toremove gas afterward. With appropriate electrolytes andelectrode polarities, such devices can produce either acidor base or salt. In regard to ionic transport, the behaviorof these devices fully corresponds to that of a semiconductor diode. To our knowledge, this is the first time suchcomplete equivalence of ion transport through ion-exchange media and with the more familiar example ofelectron transport through a semiconductor diode underboth forward- and reverse-biased conditions have beendemonstrated. Reverse bias can be applied to minimize/prevent Donnan-forbidden leakage or ion exchange. Evenwith 4 M KOH in the electrode compartments and 4 L/min water flowing through the eluent channel, with areverse bias of -12 V, the leakage KOH concentration is<30 M, whereas the KOH concentration with zerovoltage applied, hereinafter termed open circuit penetration (OCP), is 1600 M. It is suggested that this OCPoccurs not as much through Donnan-forbidden leakagebut via ion exchange. Chromatograms and reproducibilitydata are presented for both isocratic and gradient chromatography, using ion-exchange, latex-modified, opentubular and packed monolithic columns.