Simultaneous detection of dopamine and ascorbic acid using silver/silver sulfide modified carbon nanotube electrodes

• Ag/Ag2S, as a catalytic, improved electrode activity for DA and AA.
• The peaks became sharper for AA with Ag/Ag2S-modified CNT electrode.
• The modified electrode simultaneously detected DA and AA with good peak separation.
• The modified electrode had higher sensitivity and wider concentration ranges.
• The modified electrode is a disposable electrode.

In this study, silver/silver sulfide (Ag/Ag2S) was applied on an electrochemical system for the simultaneous determination of dopamine (DA) and ascorbic acid (AA) in phosphate buffer solution (pH 7.0). The Ag/Ag2S nanoparticles were dispersed with carbon nanotube (CNT) in Nafion to be an Ag/Ag2S-immobilized CNT electrode. The electrochemical behaviors of DA and AA were examined using the differential pulse voltammetry (DPV) technique. The characteristic peaks of DA and AA in the differential pulse votammogram were well separated. Without Ag/Ag2S, CNT electrode cannot detect AA. When Ag/Ag2S nanoparticles were immobilized on the CNT electrode, the sensitivity to DA increased from 0.637 to 1.000 μA μM−1 cm−2, and the sensitivity to AA became 0.020 μA μM−1 cm−2 in the linear concentration range of 250–2000 μM.