A highly sensitive electrochemical determination of l-tryptophan in the presence of ascorbic acid and uric acid using in situ addition of tetrabutylammonium bromide on the ß-cyclodextrin incorporated multi-walled carbon nanotubes modified electrode

Abstract

A novel type of modified electrode based on in situ addition of tetrabutylammonium bromide on the ß-cyclodextrin incorporated with multi-walled carbon nanotubes modified glassy carbon electrode (TBABr⋅⋅⋅ß-CD/MWCNTs/GCE) was fabricated to study the electrochemical behavior of l-tryptophan (Trp) in the presence of ascorbic acid (AA) and uric acid (UA). The TBABr⋅⋅⋅ß-CD/MWCNTs/GCE showed excellent electrochemical catalytic activities for the determination of Trp by differential pulse voltammetry (DPV) and offered anodic peak at 0.75 V. The electrochemical behavior of Trp at the TBABr⋅⋅⋅ß-CD/MWCNTs/GCE revealed higher oxidation current and lower oxidation potential than ß-CD/MWCNTs/GCE, MWCNTs/GCE and bare GCE. The DPV provided a linear relationship to the Trp concentration of 1.5–30.5 μM. The low detection limit of Trp was 0.07 μM based on signal to noise ratio (S/N) of 3. The electrochemical sensor demonstrated an excellent selectivity and sensitivity, good stability and reproducibility. The TBABr⋅⋅⋅ß-CD/MWCNTs/GCE was applied to the detection of Trp in the presence of AA and UA in human serum samples and gave recoveries of 92.0–101.0 %.