Analytical Aplication of Dipon Ligand
| Authors | |
|---|---|
| Year of publication | 2003 |
| Type | Article in Proceedings |
| Conference | Book of Abstracts of XXVIII International Symposium on Macrocyclic Chemistry, Gdansk, Poland, July 13-18 2003 |
| MU Faculty or unit | |
| Citation | |
| Field | Analytic chemistry |
| Keywords | 1;4;8;11-tetraazacyclotetradecane-1;8-bis(methylphosphonic) acid; kinetic determination; volumetric determination; capillary zone electrophoresis determination |
| Description | Complexation reactions of macrocyclic ligands are widely utilized in analytical chemistry. Such ligands show high ion selectivity or catalytic activity of their complexes on chemical reactions. They can be applied for determination of inorganic as well as organic cations, anions and neutral compounds. In this work, the possible applications of macrocyclic ligand 1,4,8,11-tetraazacyclotetradecane-1,8-bis(methylphosphonic) acid, (dipon) in analytical chemistry were examined. The ligand exhibits extraordinary thermodynamic and kinetic stability of copper(II) complex in comparison to other metal ions. Three possibilities of utilization of dipon for copper analysis were proposed: i)kinetic determination, ii)volumetric determination (dipon as sequestering titration agent), iii)capillary zone electrophoresis (CZE) determination. For kinetic determination of copper, the effect of interfering ions also forming complexes with dipon (Zn2+, Cd2+, Pb2+, Mn2+, Ca2+, Ni2+, Co2+, Mg2+) was studied. The high selectivity of copper determination was detected in case of low excess of interfering ions. Since a decrease of sensitivity was observed in real samples (alloys, mineral water) with high excess of interfering ions, the standard addition method was used here. The linear calibration curve has a dynamic range (5-250)*10-6 mol.l-1 (0.3-16 ppm) and detection limit of the method is 5*10-6 mol.l-1 (0.3 ppm). Microtitration method with spectrophotometric indication of equivalence point was developed for copper determination in high content copper alloys. Accuracy of the copper assay determined by volumetry was lower than 5% for samples of different composition alloys. The advantage of proposed method is that it is not necessary to use masking agents for the other metal ions as in case of other chelatometric titrations. Dipon was also used as selective agent for CZE copper determination in biological samples (human serum). Because of complicated matrix in such sample, the detection limit was 300 times higher than that one for aqueous solutions, therefore proposed method can be only used for determination of relatively high concentration of labile copper in biological samples as consequence of Wilson disease or copper intoxication. |
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