Graphite oxide bulk modified carbon paste electrode for the selective detection of dopamine: A voltammetric study

A novel electrochemical sensor for the selective and sensitive detection of dopamine (DA) in presence of large excess of ascorbic acid (AA) and uric acid (UA) at physiological pH was developed by the bulk modification of carbon paste electrode (CPE) with biocompatible graphite oxide (GO). Very small quantity of GO in carbon paste matrix imparted selectivity through electrostatic interactions. The modifier was characterized using infrared spectroscopy and powder X-ray diffraction. Large peak separation, good sensitivity and stability allow this modified electrode to analyze DA individually and simultaneously along with AA and UA. Applying differential pulse technique, DA could be detected even in the presence of 1000 fold excess of AA and UA. A linear dynamic range of 0.07–70 μM with detection limit of 1.5 × 10−8 M was obtained for DA. None of the bulk modified electrodes reported in the literature have shown such a low detection limit at the physiological pH. The practical application of the modified electrode was demonstrated by spiking the human blood serum and cerebral fluid with dopamine and the results obtained were satisfactory.

The differential pulse voltammogram obtained at graphite oxide bulk modified carbon paste electrode shows good resolution of anodic peaks for the detection of the neurotransmitter dopamine in a mixture containing ascorbic acid and uric acid at physiological pH. The modified electrode has been successfully applied for the determination of dopamine in real sample analysis and hence it can be used as a sensor for the detection of dopamine in presence of ascorbic acid and uric acid.Figure optionsDownload as PowerPoint slideHighlights
► None of the bulk modified electrodes have shown such a low detection limit for the detection of dopamine at pH 7.
► Ease of preparation and good analytical response supports its claim for use as a potential dopamine sensor.
► Has enhanced current sensitivity, stability, reproducibility and selectivity.
► Good peak separation for dopamine in presence of thousand folds excess of ascorbic acid.