Multi-walled carbon nanotubes/electro-copolymerized cobalt nanoparticles-poly(pivalic acid) composite film coated glassy carbon electrode for the determination of methimazole

A reproducible voltammetric method is described for the determination of methimazole based on the modification of a glassy carbon electrode with multi-walled carbon nanotube/electro-copolymerized cobalt nanoparticles-poly(pivalic acid) composite. The modified electrode exhibited a highly electrocatalytic effect toward the oxidation of methimazole with a good reproducibility. Compared with a number of modified electrodes including a bare GCE, the poly(pivalic acid)-CoNPs/MWCNT/GCE exhibits a distinct shift of the oxidation potential of methimazole in the cathodic direction and a marked enhancement of the current response. This enhancement was mainly contributed to the combination of the advantageous of multi-walled carbon nanotubes, cobalt nanoparticles and poly(pivalic acid) composites coated electrode. The results showed that methimazole exhibited a well defined oxidation peak at 255 mV. The modified electrode was used for the determination of methimazole in 0.1 M phosphate buffer solution (PBS) at pH 7.2. The peak current increased linearly with the concentration of methimazole in the range of 1.0 × 10−7–3.0 × 10−4 M with a correlation coefficient of 0.9996. The detection limit was 9.36 × 10−9 M (S/N = 3). The relative standard deviation (RSD) of 10 successive scans was 1.6% for 20 μM methimazole. The proposed method was successfully applied to the determination of methimazole in thyramozol tablets.