A SELECTIVE SENSING OF DOPA IN THE PRESENCE OF ADRENALINE

A polycarbazole electrode has been developed, which selectively senses L-dopa (3,4-dihydroxy-L-phenylalanine) in a solution containing a mixture of L-dopa and adrenaline. This sensing uses the cyclic voltammetric response of the electrode for L-dopa, which shows an anodic peak at +0.22 V versus SCE. The complementary peak of dopaquinone occurs at +0.15 V. The polycarbazole electrode does not sense the presence of adrenaline, although its electrochemical oxidation at a Pt electrode occurs at +0.50 V. The polycarbazole electrode has been used for the determination of L-dopa in the presence of adrenaline in the concentration range 1-10 mM. Amperometric sensing of L-dopa is carried out at 0.40 V and is successful in the above concentration range.