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.