A novel fused-silica capillary dropping mercury electrode with long drop-time and its application on determination of critical micelle concentration |
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Authors: | Sou?ková Jitka Skopalová Jana Muller Luká? Vymětalíková Michaela Barták Petr |
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Institution: | Department of Analytical Chemistry, Faculty of Science, Palacký University, 17 Listopadu 1192/12, 77146 Olomouc, Czech Republic |
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Abstract: | A novel long drop time mercury electrode has been constructed from common fused-silica capillary (50 μm I.D., 360 μm E.D.). Proposed device provides reproducible mercury drops with typical lifetime 40-120 s. The electrode was used for a set of electrocapillary measurements aimed at determination of critical micelle concentration of anionic surfactants by a convection controlled drop-time technique. A critical micelle concentration of sodium dodecyl sulfate 5.6 ± 0.4 mmol L−1 and 4.3 ± 0.4 mmol L−1 were obtained in 1 mmol L−1 and 5 mmol L−1 phosphate buffer (pH 7.0), respectively. The values were comparable to those obtained from conductometric measurements under the same conditions (7.0 ± 0.1 mmol L−1 and 5.2 ± 0.1 mmol L−1, respectively) and the difference was explained in accordance with theory of hemi-micelle formation. |
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Keywords: | Electrocapillary measurement Dropping mercury electrode Critical micelle concentration Fused-silica capillary Sodium dodecyl sulfate |
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