Analytical Sciences

Simultaneous Determination of Inorganic Cations by Capillary Ion Chromatography with a Non-suppressed Contactless Conductivity Detector

Li RONG,*,** Zhiguo LIU,* Menglin MA,* Jiaqin LIU,* Zhihong XU,* Lee Wah LIM,** and Toyohide TAKEUCHI**

*Department of Chemistry, School of Physics and Chemistry, Xihua University, 999 Jinzhou-Road, Chengdu 610039, P. R. China
**Department of Chemistry, Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan

A non-suppressed capillary ion chromatographic method with a laboratory-made packed cation-exchange column (100 mm × 0.32 mm i.d.) was developed for the separation and simultaneous determination of five common inorganic cations (sodium, ammonium, potassium, magnesium and calcium). Cation exchangers were prepared by the reaction of the hydroxyl group on the surface of diol-group bonded silica gel with 1,3-propanesultone in methanol. Simultaneous separation of these five common inorganic cations were achieved within 17 min using 1 mM methanesulfonic acid and 0.1 mM 15-crown-5 ether in methanol–water (8:2, v/v) as the eluent. The effects of organic solvents and crown ethers in the eluent on the retention of analytes were investigated. The limits of detection (S/N = 3) of the cations were in the range of 18 – 124 μg/l, the linear correlation coefficients were 0.9991 – 0.9998, and the RSD values of retention time and peak height were all smaller than 2.1%. The present analytical method was successfully applied to the rapid and direct determination of inorganic cations in samples of river water and commercial drinks, with satisfactory results.

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