Novel Polymer Modified Electrodes for Sensitive and Selective Detection of Dopamine and Uric Acid

Grzegorz Milczarek ,  Aleksander Ciszewski 

Poznań Technical University, Institute of Chemistry and Applied Electrochemistry, Piotrowo 3, Poznań 60-965, Poland

Abstract

2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (BAHHFP) was electropolymerized oxidatively on a glassy carbon electrode by cyclic voltammetry. Activity of the polymer modified electrode towards ascorbic acid (AA), uric acid (UA) and dopamine (DA) was characterized by cyclic voltammetry (CV) and differential puls voltammetry (DPV). The response of AA was drastically suppresseed and shifted towards more negative potentials at the electrodes modified by the electropolymerized films. Simultaneously, reversibility of both the DA and UA electrode reaction was enhanced. Unusual, selective preconcentration features were observed for DA when the polymer modified electrode was polarized at negative potentials. In a ternary mixture containing the three analytes studied, three baseline resolved DPV peaks are observed. At physiological pH=7.4, after 5 min of preconcentration at -300 mV, peak positions were -0.073, 0.131 and 0.280 V vs. Ag/AgCl for AA, DA and UA, respectively. Relative selectivities, DA/AA and UA/AA, exceeded 4000:1 and 700:1, respectively. The DA response was linear in the range 0.05-3 μM with sensitivity of 138 μA μM-1 cm-2 and detection limit (3 s) of 5 nM. Sensitive quantification of UA was possible in acidic solution (pH=1.8). Under these conditions a very sharp DPV peak appeared at 630 mV. The response was linear in the range 0.5-100 μM with sensitivity of 4.67 μA μM-1 cm-2 and detection limit (3 s) of 0.1 μM. Practical utility was illustrated by selective determination of UA in human urine.

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Presentation: Short communication at SMCBS 2003 Workshop, by Grzegorz Milczarek
See On-line Journal of SMCBS 2003 Workshop

Submitted: 2003-09-15 10:17
Revised:   2009-06-08 12:55
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