Determination of dopamine in rat striatum by microdialysis and high-performance liquid chromatography with electrochemical detection on a functionalized multi-wall carbon nanotube electrode.

High performance liquid chromatography coupled with microdialysis sampling and electrochemical detection (HPLC-ECD) has been used to determine dopamine (DA). In the HPLC-ECD a multi-wall carbon nanotube electrode chemically modified with carboxyl groups (MWNT-COOH CME) was used as the working electrode for determination of DA. The results indicated that the MWNT-COOH CME enabled efficient electrocatalytic oxidation of DA with relatively high sensitivity and stability and long life. Peak currents for dopamine were linearly dependent on concentration in the range 5.0 x 10(-9) to 5.0 x 10(-5) mol L(-1) and the calculated detection limit (S/N=3) was 2.5 x 10(-9) mol L(-1). The method had been successfully used to measure dopamine in rat striatal microdialysate. To study the physiological effect of nitric oxide (NO) on striatal release of DA, 0.5 mmol L(-1) sodium nitroprusside (SNP) was a continuously perfused into rat striatum. This resulted in a 46% increase in DA basal level.