Voltammetric determination of pentachlorophenol with a silica gel-modified carbon paste electrode |
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Institution: | (1) Department of Analytical Chemistry, Faculty of Chemistry, Complutense University of Madrid, E-28040 Madrid, Spain |
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Abstract: | Summary The anodic voltammetric behaviour of pentachlorophenol at a silica gel-modified carbon paste electrode in aqueous solution
is reported. Adsorption of the fungicide onto the electrode under open-circuit conditions is followed by application of either
differential or square wave voltammetry. The results obtained by differential pulse voltammetry at pH 2.9, with a modifier
concentration of 10% and accumulation times of 120 and 300 s, allowed the development of a method to determine pentachlorophenol
in the ranges of 1.0×10−6–1.0×10−5 and 1.0×10−7–1.0×10−6 mol l−1. The relative standard deviation is 2.6% for a concentration of 2.0×10−7 mol l−1, with a detection limit of 1.8×10−8 mol l−1 (5 ppb). The effect of other chlorophenols was studied. The results obtained by square wave voltammetry showed a behaviour
typical of an irreversible electron transfer. Amplitude, step height and frequency were optimised, taking into account the
resolution of the voltammetric response. No improvement in sensitivity was obtained with respect to DPV. Good results were
obtained by applying the proposed differential-pulse voltammetric method to the determination of pentachlorophenol in a commercial
fungicide. |
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