Sol-gel derived metal dispersed ceramic-graphite composite electrode for amperometric determination of dopamine

A new silver dispersed composite electrode made of sol-gel derived ceramic-graphite has been demonstrated for the determination of dopamine. Silver has been immobilized within the porous and rigid silicate network in the composite by the specific interaction with (3-mercaptopropyl)trimethoxysilane (MPS). The modified composite electrode coated with Nafion exhibited good catalytic activity for the oxidation of dopamine at a reduced potential of 0.35 V with good sensitivity and selectivity. The sensor showed a linear response to dopamine in the concentration range from 6.6×10⁻⁶ to 1.2×10⁻³ M with a correlation coefficient of 0.9987. The electrode surface can be easily renewed by a simple mechanical polishing and has the advantages of good reproducibility, rapid response and remarkable stability.