A dual-template imprinted polymer-modified carbon ceramic electrode for ultra trace simultaneous analysis of ascorbic acid and dopamine

A dual-template imprinted polymer film containing dispersed multiwalled carbon nanotubes was exploited in the fabrication of a typical, reproducible, and rugged carbon ceramic electrode, adopting “surface grafting from” approach for the growth of a nanometer thin coating on its surface. For this, chloro groups were first introduced at the exterior surface of silica-carbon composite electrode through sol-gel modification using (3-chloropropyl)-trimethoxysilane, followed by an iniferter (sodium diethyl dithiocarbamate) initiated photopolymerization of functional monomer (2,4,6-trisacrylamido-1,3,5-triazine), mixed templates (ascorbic acid and dopamine), and cross-linker (ethylene glycol dimethacrylate), in the presence of multiwalled carbon nanotubes. The modified sensor was validated for the simultaneous analysis of ascorbic acid and dopamine in aqueous, blood serum, cerebrospinal fluid, and pharmaceutical samples, using differential pulse anodic stripping voltammetric technique. The oxidation peak potentials for both analytes were found to be well apart approximately by 300 mV, which was large enough to allow selective and sensitive analysis of one in the presence of other, without any cross reactivity, interferences and false-positives. The detection limits realized by the proposed sensor, under optimized conditions, were found to be as low as 2.24 ng mL−1 for ascorbic acid and 0.21 ng mL−1 for dopamine (S/N=3). Such stringent limits could be considered suitable for the primitive diagnosis of several chronic diseases, in clinical settings.