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Amperometric Determination of Calcium Ion with an Alizarin/Nafion Modified Electrode
Author(s) -
Jo Guebong,
Won MiSook,
Shim YoonBo
Publication year - 1999
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/(sici)1521-4109(199908)11:12<885::aid-elan885>3.0.co;2-y
Subject(s) - chronoamperometry , nafion , analytical chemistry (journal) , chemistry , amperometry , electrode , detection limit , cyclic voltammetry , alizarin , ion , electrochemistry , chromatography , nuclear chemistry , organic chemistry
Determination of Ca 2+ ions with 4 μL –5.0×10 –3 M alizarin and 5 % Nafion‐modified electrode was studied employing cyclic voltammetry and chronoamperometry. The Nafion film fabricated in different humidities gave different responses for the Ca 2+ ion, of which morphology was characterized with atomic force microscope. Various experimental parameters, which influenced the sensitivity of the modified electrode to Ca +2 ions, were optimized. The modified electrode covering the Nafion film at the low humidity of 40 % was stable in all experiments. The electrodes were stable over pH 4–12 and cation interference could be avoided by controlling the pH of the sample solution. The linear response range for Ca 2+ ions employing double potential chronoamperometry was 2.0×10 4 –1.5×10 6 M. Least square analysis provided two equations I [mA]=–0.668 –0.136 C [10 5 M] and I [mA]=–0.566 –0.0185 C [10 5 M]. The correlation coefficients were 0.997 for both cases. The relative standard deviation was ±4.7 % at 1.0×10 –5 M for five determinations. From the signal‐to‐background characteristics of the response, the detection limit was about 1.0×10 –6 M. Satisfactory results were acquired for the determination of the Ca 2+ ion in the certified standard urine reference material (SRM's 2670) and in tap water.