| Abstract: | A new amperometric sensor for the determination of trichloroacetic acid (TCA) was developed based on the immobilization of myoglobin/colloidal gold nanoparticles in titania sol–gel matrix. The sensor showed a pair of well‐defined and nearly reversible cyclic voltammetric peaks for the Mb Fe(III)/Fe(II) with a formal potential (E°′) of ?335 mV and a peak‐to‐peak separation was 61 mV vs. Ag/AgCl (3.0 M KCl) at 100 mV s?1 in 0.1 M pH 7.0 phosphate buffer solutions (PBS). The formal potential of the Mb Fe(III)/Fe(II) couple shifted linearly with the pH with a slope of ?51.3 mV/pH, indicating that an electron transfer accompanies single‐proton transportation. The sensor displayed a good electrocatalytic response toward the reduction of TCA and the catalytic mechanism was also discussed. The overpotential for the reduction of TCA was lowered by at least 0.8 V compared with that obtained at bare glassy carbon electrode. The linear range spans the concentration of TCA from 2.0×10?6 to1.2×10?5 M and the detection limit was 1.2×10?7 M. In addition, the stability, repeatability and selectivity of the sensor were also evaluated. |
