Highly Sensitive and Selective Detection of Dopamine at Poly(chromotrope 2B)-Modified Glassy Carbon Electrode in the Presence of Uric Acid and Ascorbic Acid

A highly sensitive and selective electrochemical method based on a poly(chromotrope 2B)-modified anodized glassy carbon electrode (PCHAGCE) was developed for the determination of dopamine (DA) in the presence of uric acid (UA) and ascorbic acid (AA). The PCHAGCE sensor exhibited excellent electron-mediating behavior towards the oxidation of DA in 0.1 M phosphate buffer solution (PBS) (pH 7.0). It was found that the electrocatalytic activity was significantly dependent on the charge status and molecular structure of the target molecules. Differential pulse voltammetry (DPV) measurements revealed oxidation signals for DA, UA, and AA that were well-resolved into three distinct peaks with AA-DA, DA-UA, and AA-UA peak potential separations (ΔE_p) of 172, 132, and 304 mV, respectively. A detection limit of 0.04 ± 0.001 μM (S/N = 3) and a quantification limit (S/N = 10) of 0.149 ± 0.03 μM were obtained for DA sensing in a linear range of 1 to 40 μM in PBS (pH 7.0) with a very high sensitivity of 1.522 ± 0.032 μA·μM^-1. The DA concentrations in human urine samples were also successfully determined with recoveries of 94.0-98.0%. This approach provides a simple, easy, sensitive, and selective method to detect DA in the presence of AA and UA.