Electrochemical determination of triclosan at a mercury electrode

Abstract

A voltammetric method for the determination of trace amounts of triclosan was developed. Differential pulse voltammetry of triclosan exhibits tensammetric peak at the adsorption and desorption potential of triclosan. In the potential range where adsorption occurs, the base current is depressed. The determination method is based on the adsorption of triclosan on hanging mercury drop electrode and desorption of triclosan at negative tensammetric peak. The system showed no positive tensammetric peak on hanging mercury drop electrode under the experimental conditions. The tensammetric peak potential of triclosan was between −1190 and −990 mV (versus Ag/AgCl), depending on pH, scan rate, accumulation potential, accumulation time and presence of organic materials. Variation of the scan rate between 80 and 500 mV s −1 caused a linear increase in the tensammetric peak height. The peak current was proportional to the concentration of triclosan over the range 2.5–60 μg l −1. Under optimum experimental conditions (pH=7, accumulation potential of −450 mV and accumulation time of 90 s), the detection limit (DL) was obtained as 1.9 μg l −1 and the relative standard deviation (R.S.D.) was lower than 3%. The method was applied to the determination of triclosan in samples of toothpaste (containing 0.3% triclosan) and wastewater.