Nanomolar and selective determination of epinephrine in the presence of norepinephrine using carbon paste electrode modified with carbon nanotubes and novel 2-(4-oxo-3-phenyl-3,4-dihydroquinazolinyl)-n′-phenyl- hydrazinecarbothioamide

A novel modified carbon nanotube paste electrode of 2-(4-oxo-3-phenyl-3,4- dihydro-quinazolinyl)-N′-phenyl-hydrazinecarbothioamide (2PHC) was fabricated, and the electrooxidation of epinephrine (EP), norepinephrine (NE), and their mixture has been studied using electrochemical methods. The modified electrode displayed strong catalytic function for the oxidation of EP and NE and resolved the overlap voltammetric response of EP and NE into two well-defined voltammetric peaks of about 240 mV with square wave voltammetry (SWV). A linear response in the range of (5 × 10-8)-(5.5 × 10 -4) M with a detection limit (S/N = 3) of 9.4 nM for EP was obtained. © 2008 American Chemical Society.