Application of Ion-exchange Polymer Modified Electrode on Trace Analysis
| Autor: | Hao-Yun Yang, 楊浩筠 |
|---|---|
| Rok vydání: | 1999 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 87 This project is to develop two analytical procedures for the determination of tellurium in aqueous samples by square-wave cathodic stripping voltammetry. In the first procedure, a Nafion/oxine coated mercury film chemically modified (NOMF) electrode for the determination of the anionic tellurium(IV) is described. In order to adapt to various matrixes for the determination of tellurium(VI), a Tosflex/oxine coated mercury film electrode (TOMF) electrode is developed for trace analysis of cationic tellurium in chloride media. As the result, both Nafion and Tosflex modified electrode showed improved resistance to interference from surface-active compounds on the determination of tellurium(IV), especially for sodium dodecyl sulphate which is generally considered as a major interference in the determination of tellurium at a hanging-mercury drop electrode. In the procedures, addition of EDTA in the sample solution effectively eliminated the interference from metal ions, such as molybdenum(VI), lead(II), and cadmium(II) which are capable of forming complexes with oxine.. Good sensitivity was achieved through the catalytic process between oxine and tellurium. For NOMF modified electrode, linear calibration graphs were obtained over the range 1-80 ppb of tellurium(IV), with a detection limit (3×blank signal) of 0.2 ppb. For TOMF modified electrode, the calibration plot thus obtain showed a linear behavior between 1 and 100 ppb of tellurium with a sensitivity of 2.6μA per ppb. The detection limit for TOMFE, defined as the concentration of the analyte resulting a signal three times the standard deviation of the blank, was 0.2 ppb. The TOMF electrode is easy to prepare and chemically more stable than other anion-exchange polymer modified electrodes such as polyvinylpridine modified mercury film electrode. |
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