Determination of common inorganic anions and cations by non-suppressed ion chromatography with column switching
2008
Amīn, Muḥammad | Lim, Lee Wah | Takeuchi, Toyohide
An ion chromatography (IC) method has been proposed for the determination of seven common inorganic anions (F⁻, H₂PO₄ ⁻, NO₂ ⁻, Cl⁻, Br⁻, NO₃ ⁻, and SO₄ ²⁻) and/or five common inorganic cations (Na⁺, NH₄ ⁺, K⁺, Mg²⁺, and Ca²⁺) using a single pump, a single eluent and a single detector. The present system used cation-exchange and anion-exchange columns connected in series via a single 10-port switching valve. The 10-port valve was switched for the separation of either cations or anions in a single chromatographic run. When 1.0mM trimellitic acid (pH 2.94) was used as the eluent, the seven anions and the five cations could be separated on the anion-exchange column and the cation-exchange column, respectively. The elution order was found to be F⁻ <H₂PO₄ ⁻ <NO₂ ⁻ <Cl⁻ <Br⁻ <NO₃ ⁻ <SO₄ ²⁻ for the anions and Na⁺ <NH₄ ⁺ <K⁺ <Mg²⁺ <Ca²⁺ for the cations. Complete separation of the above anions or cations was demonstrated within 35min each. Detection limits calculated at S/N=3 were 0.05-0.58ppm (mg/l) for the anions and 0.05-0.38ppm for the cations, whereas repeatability values were below 2.26, 2.76, and 2.90% for peak height, peak area and retention time, respectively. The method was successfully applied to the determination of inorganic anions and cations in river water samples.
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