´
´
J. Taborsky et al.
software NOVA 1.10 was used for voltammetric experi-
ments with three-electrode system consisting of a glassy
carbon working electrode (GCE, disc diameter 3.0 mm,
Bioanalytical Systems, USA) or rotating GCE (disk
diameter 2.0 mm, Metrohm, The Netherlands), platinum
wire auxiliary electrode, and saturated calomel reference
electrode. GCE was polished using aqueous suspension of
alumina powder (0.05 lm particles, Sigma-Aldrich) on a
wet microcloth (Buehler, USA) and sonicated in distilled
water for 30 s prior to each measurement. Cyclic voltam-
metry (CV) and linear sweep voltammetry (LSV) were
performed at different scan rates over the range 0.02–0.8 V
s-1 and at different pH values of the supporting buffer
solution. Differential pulse voltammograms were recorded
at pulse amplitude of 25 mV, pulse width 500 ms and scan
rate 0.02 V s-1. Hydrodynamic measurements were car-
ried out with angular velocity ranged from 52 to
314 rad s-1 and scan rates 0.02 and 0.4 V s-1. All exper-
iments were performed in supporting electrolytes
containing BR buffer solutions of desired pH and ace-
tonitrile (1:1, v/v). Hydrodynamic voltammograms were
processed using el-Chem Viewer software [26].
(ESA, Chelmsford, MA, USA) connected to the poten-
´
ˇ´
tiostat Detector ADLC 1 (Laboratornı prıstroje Praha,
Czech Republic). Working ZOP solution (5 9 10-4
mol dm-3) in 1:1 (v/v) acetonitrile/ammonium acetate
buffer solution (pH 3.5, pH 6.8, and pH 9.5) was used for
on-line oxidation in the potential range from 0 to 0.8 V (vs.
Pd/H2).
Acknowledgments The authors gratefully acknowledge the finan-
cial support by the Ministry of Education, Youth and Sports of the
Czech Republic (project LO1305).
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ments were performed using ESA Conditioning cell 5021A
123