Simultaneous determination of ascorbic acid and dopamine at a sol–gel composite electrode

A new sol–gel composite electrode containing dispersed copper was fabricated using (3-mercaptopropyl)trimethoxysilane (MPS) and copper nitrate. The sensor exhibited excellent characteristics for simultaneous determination of ascorbic acid and dopamine owing to its combined features of sol–gel composite and copper catalysis. The peaks for the oxidation of ascorbic acid and dopamine were well resolved at the reduced potentials with good sensitivity. A linear response to ascorbic acid and dopamine was observed in the concentration range from 1.6×10−5 to 5.0×10−3 M and 7.3×10−6 to 2.2×10−3 M with a correlation coefficient of 0.9987 and 0.9979, respectively. The proposed sensor has promising features such as, ease of fabrication, good reproducibility, high stability and the easy surface renewal by simple polishing.