Detection of neurotransmitters using metallophthalocyanines as electrocatalysts

Abstract

Some metallophthalocyanine complexes were synthesized and their catalytic activities towards the detection and quantification of the neurotransmitters dopamine, serotonin and histamine were investigated. The study of the possible interaction between these transmitter substances and the metallophthalocyanine complexes was undertaken. Dopamine, serotonin and histamine formed complexes with Iron (II) tetrasulfophthalocyanine. The rate and equilibrium constants obtained for the coordination are in the range of values reported in the literature for ligand coordination to iron phthalocyanine complexes. Carbon paste electrodes of millimetric diameters modified with Iron (II) tetrasulfophthalocyanine exhibited good electro catalytic activity towards the detection and analysis of dopamine and serotonin while at the same time eliminated the problem of interference posed by ascorbic acid in the electrochemical analysis of neurotransmitters. A detection limit of the order of 10-6 mol dm-3 was obtained for both dopamine and serotonin at the modified electrodes. Carbon paste ultra micro electrodes modified with iron (II) tetrasulfophthalocyanine were also used for the detection of dopamine and serotonin as well as the simultaneous determination of dopamine and ascorbic acid in a mixture. The detection limit obtained for dopamine at the ultra microelectrode was 4.2xlO-7 mol dm-3 The electrode kinetics of vitamin BI as well as the stability of the electrode towards its determination was improved upon by modifying carbon paste electrodes with manganese phthalocyanine. The modified electrodes were used for the analysis of vitamin BI in tablets.