Simultaneous voltammetric determination of acetaminophen and dopamine using a glassy carbon electrode modified with copper porphyrin-exfoliated graphene

Graphene nanosheets (GSs) were prepared via liquid-phase non-covalent exfoliation of graphite powder in N,N-dimethylformamide under the assistance of copper(II) meso-tetra(4-carboxyphenyl)porphyrin tetrasodium salt Na-4(CuTCPP). A glassy carbon electrode (GCE) was modified with a film of such GSs which, due to the good electrical conductivity of graphene and the electrocatalytic properties of Na-4(CuTCPP), is capable of simultaneous determination of acetaminophen (AC) and dopamine (DA). The peak currents, best measured at voltage of 0.2 V (for DA) and 0.4 V (for AC; both vs. SCE), increase linearly in the 0.0024-3.6 mu M and 0.004-7.6 mu M concentration ranges, respectively. The detection limits are 0.8 nM for DA and 0.7 nM for AC. The sensor was successfully applied to the simultaneous determination of AC and DA in pharmaceutical preparations and spiked human serum. The results were in good agreement with those obtained for the same samples by HPLC.