Voltammetric determination of estrone based on the enhancement effect of surfactant and a MWNT film electrode

The multi-walled carbon nanotubes (MWNT) was noncovalently functionalized with Congo red (CR), resulting in a water-soluble MWNT-CR. Then, a MWNT-CR film-modified glassy carbon electrode (denoted as MWNT-CR/GCE) was prepared through the dip-coating method. The electrochemical behavior of estrone at the GCE and MWNT-CR/GCE was investigated, showing that the MWNT-CR/GCE greatly enhances the oxidation signal of estrone. Moreover, the electrochemical response of estrone in the absence and presence of cetyltrimethylammonium bromide (CTAB) was examined. It was found that the oxidation peak current of estrone at GCE and MWNT-CR/GCE remarkably increases in the presence of CTAB, suggesting that CTAB possesses efficient enhancement effect to estrone. Based on this, a sensitive electrochemical method was proposed for the determination of estrone. The Effects of pH value, concentration of CTAB, scan rate and amount of MWNT-CR were studied. The linear range is over the range from 5.0 × 10− 8 to 2.0 × 10− 5 mol L− 1, and the limit of detection is evaluated to be 5.0 × 10− 9 mol L− 1. Finally, this method was successfully used to determine the content of estrone in the tablets.