Determination of coumarins by voltammetric techniques in micellar and emulsified media |
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Authors: | JM Pingarron Carrazon A Gordon Vergara AJ Reviejo Garcia LM Polo Diez |
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Institution: | Department of Analytical Chemistry, Faculty of Chemistry, Complutense University of Madrid, 28040- Madrid Spain |
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Abstract: | An electroanalytical study of the oxidation processes of umbelliferone and hymecromone at a glassy carbon electrode in micellar solution and emulsified medium by different voltammetric techniques is described. The non-ionic surfactant Triton X-405 in acetate-buffered medium at pH 4.8 was found to be the most suitable. Different ranges of linearity were obtained in the micellar solutions, depending on the technique used; the limits of determination for differential pulse voltammetry (DPV) at a stationary electrode were 2.9×10?6 mol l?1 and 3.3×10?6 mol l?1 for umbelliferone and hymecromone, respectively. In the emulsified medium formed with a mixture of toluene and ethyl acetate (3:2), the oxidation processes yielded similar results. With DPV, linear calibration plots were obtained in the ranges 1.0×10?5–9.0×10?7 mol l?1 umbelliferone and 1.0×10?5–2.0×10?6 mol l?1 hymecromone. The media used are predominantly aqueous so that special reference electrodes and solvent purification are not needed. |
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