Nanomolar simultaneous determination of levodopa and serotonin at a novel carbon ionic liquid electrode modified with Co(OH)2 nanoparticles and multi-walled carbon nanotubes

A novel modified carbon ionic liquid electrode is prepared as an electrochemical sensor for simultaneous determination of levodopa (L-dopa) and serotonin (5-HT). The experimental results suggest that a carbon ionic liquid electrode modified with multi-walled carbon nanotubes and cobalt hydroxide nanopartides, and coated with Nafion (Nafion/Co(OH)(2)-MWCNTs/CILE), accelerates the electron transfer reactions of L-dopa and 5-HT. In addition it shows no significant interferences of uric acid and ascorbic acid as electroactive coexistent compounds with L-dopa and 5-HT in biological systems. The fabricated sensor revealed some advantages such as convenient preparation, good stability and high sensitivity toward 5-HT and L-dopa determination. The DPV data showed that the obtained anodic peak currents were linearly dependent on the L-dopa and 5-HT concentrations in the range of 0.25-225 and 0.05-75 mu mol L-1. respectively. The applicability of the modified electrode was demonstrated by simultaneous determination of 5-HT and L-dopa in human serum. (C) 2012 Elsevier Ltd. All rights reserved.