The present work has been devoted to application of iodine-coated polycrystalline platinum electrode to separate and simultaneous analysis of hydroquinone and catechol. For a relatively short potential range, -0.2 – 0.9 V, the iodine-coated platinum electrode exhibits remarkable inertness towards adsorption and surface processes. The voltammogram of hydroquinone at iodine-coated electrode shows an anodic peak centered at 0.55 V and a cathodic peak centered at 0.33 V. Catechol voltammetric features are manifested by anodic peak centered at 0.70 V and a cathodic peak centered at 0.45 V. Excellent linearity between anodic or cathodic peak currents and hydroquinone concentration within a concentration range of 8.5x10-6 – 0.01 M was demonstrated. Similarly catechol also showed an excellent linear relationship between the peak currents and the concentration within the concentration range 5x10-5 and 0.01 M. Simultaneous determination of a mixture of hydroquinone and catechol by the developed method was applicable to analysis of mixtures of the two compounds as proved by analysis of standard mixtures of both compounds. Determination of hydroquinone in pharmaceutical bleaching creams with excellent accuracy provides an evidence for applicability of the developed method for analysis of real pharmaceutical samples.
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