A disposable electrochemical sensor for simultaneous determination of norepinephrine and serotonin in rat cerebrospinal fluid based on MWNTs-ZnO/chitosan composites modified screen-printed electrode

A new electrochemical sensor for simultaneous determination of norepinephrine (NE) and serotonin (5-HT) was fabricated. The electrochemical behavior of NE and 5-HT were investigated using CV and SWV at the MWNTs-ZnO/chitosan composites modified screen-printed electrode (MWNTs-ZnO/chitosan SPE). The results showed that the current responses of NE and 5-HT greatly enhanced due to the high catalytic activity of composites. The peak potentials of NE and 5-HT were separated at about 90   mV and 280   mV, respectively. The peak currents of NE and 5-HT were linearly dependent on their concentrations in the range of 0.5–30   μM and 0.05–1   μM, with the limit of detection of 0.2   μM and 0.01   μM, respectively. The modified electrode can be stored stably for at least 3 month at 4   °C in a refrigerator. Furthermore, the modified electrode was successfully applied to detect the level of NE and 5-HT in rat cerebrospinal fluid (CSF) with excellent selectivity and sensitivity.