Abstract
In this work a graphite pencil electrode is used to determine ascorbic acid, dopamine and serotonin. The electrochemical technique employed was cyclic voltammetry. These low cost electrodes were able to detect the biomolecules in the order of mM concentration. The oxidation peak potentials for the analytes are similar to those already reported, although a better peak definition was obtained. Also, this report includes the effect of the pH over the oxidation potential of these three species.