Selective determination of 3,4-dihydroxyphenylacetic acid in the presence of ascorbic and uric acids using polymer film modified electrode
PALRAJ KALIMUTHU and S ABRAHAM JOHN*
Department of Chemistry, Gandhigram Rural University, Gandhigram 624 302, Dindigul, India
*Corresponding author. E-mail: email@example.com
MS received 27 July 2010; accepted 3 November 2010
Abstract. We report here the highly sensitive and selective electrochemical determination of 3,4-dihydroxyphenylacetic acid (DOPAC), one of the dopamine metabolites in the presence of important interferents ascorbic acid (AA) and uric acid (UA) using an ultrathin electropolymerized film of 5-amino-1,3,4-thiadiazole-2-thiol (p-ATT) modified glassy carbon (GC) electrode in 0.20M phosphate buffer solution (pH 5.0). The bare GC electrode fails to resolve the oxidation peaks of AA, DOPAC and UA in a mixture. Further, the oxidation peak potentials of them were shifted to more positive potential with decreased peak currents in the subsequent cycles. On the other hand, the p-ATT modified electrode not only separated the voltammetric signals of AA, DOPAC and UA but also enhanced their peak currents. The amperometric current response was increased linearly with increasing DOPAC concentration in the range of 4.0 ´ 10−8 to 1.0 ´ 10−5 M and the detection limit was found to be 150pM (S/N = 3).
Graphical Abstract. 5-amino-1,3,4-thiadiazole-2-thiol was electropolymerized on glassy carbon electrode and utilised for selective determination of 3,4-dihydroxyphenylacetic acid in the presence of important interferents ascorbic and uric acids. The modified electrode showed excellent selectivity towards 3,4-dihydroxyphenylacetic acid even in the presence of 50-folds excess of ascorbic and uric acids.
Keywords. 5-Amino-1,3,4-thiadiazole-2-thiol; 3,4-dihydroxyphenylacetic acid; ascorbic acid; uric acid; amperometry.