Carbon nanotube doped poly(3,4-ethylenedioxythiophene) for the electrocatalytic oxidation and detection of hydroquinone

A sensitive amperometric sensor for the selective detection of hydroquinone in cosmetics was developed based on the excellent electrocatalytic property of carbon nanotube (CNT) doped poly(3,4-ethylenedioxythiophene) (PEDOT) conducting polymer toward the oxidation of hydroquinone. The oxidation potential of hydroquinone on the PEDOT/CNT modified carbon paste electrode was much lower than that on the bare electrode, and the charge transfer rate constant for the oxidation of hydroquinone was significantly increased from 0.45 to 1.84 s−1 after the modification with PEDOT/CNT. Under optimal conditions, the differential pulse voltammetry current of the sensor was linear with hydroquinone concentration across a 1.1–125 μM range and associated with a detection limit of 0.3 μM. Significantly, the detection limit is comparable or better than many current electrochemical hydroquinone assays, and the sensor is potentially much cheaper and easier for fabrication. The sensor was capable not only of comfortably quantifying hydroquinone in the presence of common interferences but also doing this in real cosmetics samples with satisfying accuracy.