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Accuracy Improvement When Determining Copper( II ) Ions With Zincon at Acidic Condition
Author(s) -
Lee Yesol,
Kim Ra Yun,
Eom InYong
Publication year - 2020
Publication title -
bulletin of the korean chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.237
H-Index - 59
ISSN - 1229-5949
DOI - 10.1002/bkcs.12139
Subject(s) - copper , chemistry , metal ions in aqueous solution , calibration curve , zinc , precipitation , ion , cyclohexanone , reactivity (psychology) , inorganic chemistry , metal , chromatography , detection limit , organic chemistry , medicine , physics , alternative medicine , pathology , meteorology , catalysis
2‐Carboxy‐2′‐hydorxy‐5′‐sulfoformazylbenzene has been widely used to determine Cu(II) ions. In general, basic pH condition is preferred to enhance the reactivity between metal ions and zincon. But acidic condition can be applied for copper determination because Cu(II) cannot lose reactivity at acidic condition. Also, pH = 5 condition can minimize the interference from zinc which is found together with copper in many samples. However, zincon can be precipitated at acidic condition. We minimized precipitation problem by adding cyclohexanone or the use of lower buffer concentration. Using this approach, accuracy was improved from −17.7 to 242.5% to −0.4% to 22.0%. A very linear calibration curve ( r 2 = 0.9999) was obtained for the copper concentration range of 30–2002 ng/mL. This method was successfully applied to determine copper concentration from discharged water samples. No significant interference was observed and the estimated LOD (S/N = 3) is 5.5 ng/mL.