Selective and low potential electrocatalytic oxidation and sensing of l -cysteine using metal impurity containing carbon black modified electrode

• Published in: Analytical methods Vol. 9; no. 48; pp. 6791 - 6800
• Main Authors: Sornambikai, Sundaram, Abdul Kadir, Mohammed Rafiq, Kumar, Annamalai Senthil, Ponpandian, Nagamony, Viswanathan, Chinnuswamy
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 01.01.2017
• Subjects: Amino acids; Ascorbic acid; Black carbon; Buffer solutions; Buffers (chemistry); Carbon; Carbon black; Cysteine; Detection; Dopamine; Electrochemical oxidation; Electrochemistry; Electrode potentials; Electrodes; Glassy carbon; Hypoxanthine; Impurities; Iron; Linearity; Metals; Multi wall carbon nanotubes; Nickel; Oxidation; Powder; Silver chloride; Uric acid
• ISSN: 1759-9660; 1759-9679
• DOI: 10.1039/C7AY02251D

The detection of thiol-containing amino acids, particularly l -cysteine ( l -CySH), without any interference from other biochemicals is a challenging research interest in electroanalytical chemistry. Amongst various electrodes, the nanogold modified electrode has been reported to be effective for low potential electrochemical oxidation (∼0 V vs. Ag/AgCl) and sensing of l -CySH. Herein, we report a conductive carbon black (CB, CL-08) modified glassy carbon electrode (GCE/CL-08) with a high surface area (1000 m 2 g −1 ), prepared by a simple drop-casting technique for efficient electrocatalytic oxidation at the lowest oxidation potential, −0.13 V vs. Ag/AgCl, and sensing of l -CySH in a pH 6.65 phosphate buffer solution. The trace metal impurities such as Ni (0.18 wt%) and Fe (0.42 wt%) in CL-08 are found to be key for such unique and unusual electrocatalytic property observed in this study. Compared with the multiwalled carbon nanotube and graphite powder modified electrodes, the GCE/CL-08 showed about 400 mV reduction in the oxidation potential and twenty times enhancement in the current signal for the CySH. A chronoamperometry detection of l -CySH on the GCE/CL-08 at an applied potential = −0.13 V vs. Ag/AgCl yielded a current linearity from 50 to 700 μM with a LOD = 45.87 nM. There are no interferences by common biochemicals such as ascorbic acid, dopamine, uric acid, xanthine, hypoxanthine and homo-cysteine on the l -CySH oxidation potential. Selective chronoamperometric detection of l -CySH in the blood serum demonstrated ∼100% recovery value as a validation for the present protocol.