Selective determination of
3,4-dihydroxyphenylacetic acid in the presence of ascorbic and uric acids using
polymer film modified electrode
Department of
Chemistry, Gandhigram Rural University, Gandhigram 624 302, Dindigul, India
*Corresponding
author. E-mail: abrajohn@yahoo.co.in
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.