Electrochemical determination of diphenols and their mixtures at the multiwall carbon nanotubes/poly (3-methylthiophene) modified glassy carbon electrode

A glassy carbon electrode modified with poly (3-methylthiophene) (P3MT) and coated with multiwall carbon nanotubes (MWNTs) film was fabricated and used for highly selective and sensitive determination of hydroquinone and catechol. The electrode combines the advantages of using P3MT and MWNTs, and exhibits a dramatic electro-catalytic effect on the oxidation of hydroquinone and catechol. This resulted in a marked enhancement of the current response. The peaks for hydroquinone and catechol are separated by about 101 mV in pH 6.4 phosphate buffer which enables simultaneous determination of both via cyclovoltammetry. Good linear relationships between the peak current and concentration were observed for single solution of hydroquinone (or catechol) by differential pulse voltammetry. The detection limits are 12 nmol L-1 and 40 nmol L-1 (at an S/N of 3). When simultaneously changing the concentration of both hydroquinone and catechol, the linear responses are in the range from 0.5 to 200 A mu mol L-1 for hydroquinone, and from 0.5 to 150 A mu mol L-1 for catechol, and the detection limits are 50 nmol L-1 (S/N = 3) for both hydroquinone and catechol. This method is simple, rapid, and accurate.