The SWNTs film was grown on the GC electrode by dropping a suspension of SWNTs in DMF on the GC electrode surface and then evaporating the solvent under an infrared heat lamp for 1 h, giving a modified SWNTs/GC electrode. Finally, the SWNTs/GC was rinsed thoroughly with absolute ethanol and deionized water just before use. The optimum working electrode, pH, and buffer solution were glassy carbon electrode (GC), 0.1M phosphate buffer pH 7.5 respectively. The SWNTs/DMF film on the GC surface increased linearly with the amounts of SWNTs suspension over the range from 1 to 10 mu L, and then increased slightly from 10 to 20 mu L. SWNTs suspension of 10 mu L was used for making the modified glassy carbon electrode. DPV technique was employed for the determination of dopamine. The drug samples containing dopamine obtained from Radvitee Hospital, Bangkok Thailand were tested as in the mentioned procedure.