Selective electrochemical detection of dopamine in the presence of ascorbic acid at anodized diamond thin film electrodes

Selective, highly stable determination of dopamine (DA) was achieved in cyc lic voltammetric and chronoamperometric measurements carried out at electro chemically treated conductive diamond film electrodes. The treated electrod es exhibited substantial shifts in the positive direction for the peak pote ntial for ascorbic acid (AA) oxidation, thus making it possible to discrimi nate between the DA and AA responses. Linear calibration curves were obtain ed for both a higher concentration range (1-70 mu M DA, 1 mM AA) and a lowe r range (0.1-1 mu M DA, 0.1 mM AA) using voltammetry and chronoamperometry, respectively. The detection limit appears to be on the order of 50 nM, whi ch is among the lowest values reported thus far. Selectivity was also achie ved in pH 7.0 aqueous solution using more stringent electrochemical treatme nt, but the effect was relatively short-lived (up to 2 h). (C) 1999 The Ele ctrochemical Society. S1099-0062(98)06-104-5. All rights reserved.