Study of retention behavior of anions by ion chromatography
| Authors | |
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| Year of publication | 2018 |
| Type | Article in Proceedings |
| Conference | XVIII. Workshop of Biophysical Chemists and Electrochemists |
| MU Faculty or unit | |
| Citation | |
| Web | http://www.sci.muni.cz/~labifel/files/soubory/sbornik_2018.pdf#page=72 |
| Keywords | Separation; Ion chromatography; Determination of anions; Analysis of drinking water |
| Description | Ion chromatography (IC) belongs to the large group of separation methods that are based on separation of components in sample between two immiscible phases: mobile and stationary. In IC, the substances are separated due to different strengths of coulombic interactions with the stationary phase. Short analysis times, high separation efficiency, high reproducibility and low analysis costs make this technique useful in industry, clinical laboratories, food control and environmental analysis. This work is focused on the study of retention behavior of anions by IC and influence of experimental conditions (temperature, pH) on the separation efficiency. Mixtures of anions (F-, Cl-, NO2-, Br-, NO3-, PO43-, SO42- and I-) were analyzed on the Metrohm861 Advanced Compact IC ion chromatograph (Metrohm, Switzerland) with conductometric detector and Metrosep A Supp 4 - 250/4.0 annex column. The tested concentrations were in range of 0.08-10 mg/L. The analysis was performed with flow rate F of 1 ml/min, all samples were measured three times. The study of influence of temperature and pH on the separation was the main aim of this work. It was found that higher temperature and pH significantly decrease values of retention factors kA. The biggest difference was observed in case of iodide anions, where the retention time shifted from 22 to 14 min when the temperature was increased from 22 to 50 °C. The optimal analysis conditions were pH = 10.22 and t = 22 °C. The calibration provided LOD values between 3 µg/L (in case of Cl-) and 200 µg/L (in case of I-). To demonstrate the practical relevance of the method, real samples of drinking waters were analyzed. The achieved results were in good agreement with the concentration values declared by the producers. Ion chromatography represents a valuable approach for determination of anion concentrations. We have optimized the method with respect to effect of temperature and pH on the separation efficiency, the method is suitable for analysis of real samples. Due to discovered dependences it is possible to predict theoretical values of retention factors, which could be used to estimation of anion retention. |
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