A New Highly Conducting Carbon Black (CL-08) Modified Electrode Functionalized with Syringic Acid for Sensitive and Selective L-Cysteine Electrocatalysis at Low Potential

Highly selective, sensitive and low potential detection of biological analytes by simple and rapid electrochemical technique using low cost nanocarbons is a demanding research since last decade. Herein, we report a low cost, new, nanocarbon, the carbon black (CL-08) functionalized with syringic acid (SA) modified glassy carbon electrode (GCE) for selective L-cysteine (L-CySH) electrocatalysis at 0.04 V vs Ag/AgCl. The new matrix is competitive in the low potential L-CySH detection compared to the multiwalled carbon nanotube, graphite powder, carbon mesoporous and graphitized mesoporous carbon. The possible in situ generated redox products namely 2,6-dimethoxy benzoquinone and 3,4-dihydroxy-5-methoxy benzoic acid were proposed to form on the GCE/SA@CL-08 with two electron transfer and nernstian behaviours. FTIR and UV-vis analyses collectively revealed the presence of quinone species. The GCE/SA@CL-08 showed L-CySH electrocatalysis with good selectivity, 0.42 nA.μM−1 and 5.4 nA.μM−1 sensitivity in the detection range of 20-100 μM and 100-1000 μM respectively with 639 nM limit of detection, in chronoamperometry. A successful demonstration of L-CySH detection from the simulated blood serum and processed chicken samples with substantial recovery values using the GCE/SA@CL-08 were presented in this study.