A highly sensitive electrochemical determination of norepinephrine using l-cysteine self-assembled monolayers over gold nanoparticles/multi-walled carbon nanotubes electrode in the presence of sodium dodecyl sulfate

Abstract A novel electrochemical sensor consisting of l -cysteine self-assembled monolayers over gold nanoparticles/multi-walled carbon nanotubes modified glassy carbon electrode ( l -Cys/AuNPs/MWCNTs/GCE) was fabricated and applied for the determination of norepinephrine (NE) in the presence of sodium dodecyl sulfate (SDS) for the first time. Electroanalytical measurements including cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used. The optimum buffer of pH 5.0 contained 30 μM SDS, the NE oxidation peak current enhanced linearly with concentration ranging from 0.2 to 100 μM (R 2 of 0.9998) with a detection limit of 0.03 μM. In the presence of SDS, the modified l -Cys/AuNPs/MWCNTs/GCE electrode showed high selectivity for the detection of NE in the presence of ascorbic acid and uric acid. High recoveries in the range of 80.7–100.2% were obtained in spiked human serum samples. Our modified electrode displayed a high reproducibility, sensitivity and long term stability.