Simultaneous voltammetric detection of 5-hydroxyindole-3-acetic acid and 5-hydroxytryptamine using a glassy carbon electrode modified with conducting polymer and platinised carbon nanofibers

The authors describe a method for simultaneous voltammetric determination of 5-hydroxytryptamine (serotonin; 5-HT) and its metabolite 5-hydroxyindoleacetic acid (5-HIAA). A glassy carbon electrode was modified with poly(pyrrole-3-carboxylic acid) and with platinised carbon nanofibers to obtain a sensor that can quantify 5-HT and 5-HIAA with detection limits of 10 nM and 20 nM, respectively. The peak currents, best measured at voltages of 170 mV and 500 mV (vs. Ag/AgCl) for 5-HT and 5-HIAA, increase linearly in the 0.01–100 μM concentration range for both analytes. The method was successfully applied to the quantitation of 5-HT and 5-HIAA in spiked artificial urine samples, and the sensor can be used up to 10 days.