Electrochemical detection of serotonin in the presence of 5-hydroxyindoleacetic acid and ascorbic acid by use of 3D ITO electrodes

•Electrochemical detection of serotonin in the presence of its degradation product (5-hydroxyindole acetic acid) and ascorbic acid without additional modification of the surface•Preparation of mesoporous μITO electrodes and their characterisation•Decrease of the oxidation potential of serotonin at μITO compared to flat ITO•Improvement in signal stability of serotonin at μITO•Linear calibration curve up to high serotonin concentration at μITO (from 50 μM to 1 mM with a sensitivity of 20 nA/μM)

The reproducible detection of neurotransmitters such as serotonin in the presence of interfering substances is still a topic in analytical sciences. In the present study, a 3D mesoporous ITO electrode (μITO) has been used for the determination of serotonin in the presence of high concentrations 5-hydroxyindoleacetic acid (5-HIAA) as an alternative to carbon materials. The 3D structure has been prepared via a template approach, by spin coating on top of a flat ITO electrode. It is mechanically stable allowing application in a flow cell. The detection of serotonin on μITO shows a significant decrease of the oxidation potential from 670 mV to 350 mV vs. Ag/AgCl compared to flat ITO and an improvement in the stability of the signal. The sensitivity has been evaluated by DPV (20 nA/μM) and is linear in the range of 50 μM and 1 mM. The detection limit (LOD) was calculated and is 7.5 μM for μITO. Furthermore, a clear discrimination of serotonin to 5-hydroxyindoleacetic acid - an enzymatic degradation product of serotonin - and an anodic interfering substance - ascorbic acid - can be observed.