Poly(acridine orange)-modified glassy carbon electrodes: electrosynthesis, characterisation and sensor application with uric acid

Abstract

Poly(acridine orange) was electropolymerised on glassy carbon electrodes by potential cycling in phosphate buffer solution at pH 5.5, 6.0, 7.0 and 8.0. Electrochemical behaviour of the modified electrodes was studied by cyclic voltammetry in phosphate buffer solution at various pHs and found that the best polymer film formation was obtained at pH 5.5. Quantitative determination of uric acid was achieved by cyclic voltammetry, differential pulse voltammetry (DPV) and fixed-potential amperometry in phosphate buffer solution at pH 5.5. Anodic peak currents were linearly proportional to concentration of uric acid in the range 1-75 lM for cyclic voltammetry, 0.4-75 lM for DPV and 0.04-5.3 lM for amperometry. Detection limits were 3.7 9 10 -1 , 9.7 9 10 -2 and 9.5 9 10 -3 lM for cyclic voltammetry, DPV and amperometry, respectively. The modified electrodes exhibited good sensitivity, wide linear range and good stability. There is no interference from substances commonly present in natural samples.

Poly(Methyl Red) Modified Glassy Carbon Electrodes: Electrosynthesis, Characterization, and Sensor Behavior

“…where Q is the charge corresponding to the polymer oxidation, Γ is the surface concentration of PMR, n is the number of electrons consumed in the electrode process, A is the electrode area (cm 2 ), and F is the Faraday constant , . It was assumed that two electrons were involved per monomer in the electropolymerization of MR in agreement with the literature .…”

“…The anodic and the cathodic peaks of PMR films decreased in height significantly at higher pHs than 5.0. Dependence of the peak currents, I p , on scan rate, v , was investigated and found that both anodic and cathodic peak currents increased linearly with increasing scan rate for all PMR films (Table ), showing an adsorbed species‐controlled electrode process, similar to the polymer films in the literature , . In Table , the results of the linearity were listed for only the thickest three PMR films, since the peak currents of PMR films which were not listed in Table were too low to be analyzed.…”

“…The increase of the polymer peaks and the decrease of the monomer peaks in height continued steadily with the number of cycles until the 5 th cycle at pHs 7.0 and 8.0, 30 th cycle at pH 9.0 ( Figure 1), 19 th cycle at pH 10.0, and 3 th cycle at pH 11.0. After these cycle numbers, the values of the peak currents did not increase and the peak potentials did not change significantly during the electropolymerization [29]. As a result, the fastest, controlled, and well defined PMR film formation was obtained in BRB at pH 9.0 presenting the highest peak currents of PMR, similar to what was observed at some electroactive polymers such as poly(methylene green) and poly (methylene blue) electropolymerized with the corresponding phenothiazine dyes in alkaline buffer solutions [30].…”

“…The surface of the PMR 8 modified GC electrodes was electrochemically cleaned during the subsequent measurements of UA using CV in the potential region from −0.4 to +1.2 V vs . Ag/AgCl at a scan rate of 100 mV s −1 for 3 cycles in the supporting electrolyte . Figure a and 5b showed differential pulse and cyclic voltammograms of UA at different pHs.…”

“…The anodic peak of UA disappeared in the buffer solutions at higher pHs than 8.0. The surface of the PMR 8 modified GC electrodes was electrochemically cleaned during the subsequent measurements of UA using CV in the potential region from À0.4 to + 1.2 V vs. Ag/AgCl at a scan rate of 100 mV s À1 for 3 cycles in the supporting 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 electrolyte [29]. Figure 5a and 5b showed differential pulse and cyclic voltammograms of UA at different pHs.…”