A new sensor was developed using a screen-printed carbon electrode modified with single-walled carbon nanotubes (SWCNTs) and Prussian blue (PB) coated with chitosan. The modified electrode allowed the oxidation and reduction of rutin at 0.25 and 0.096 V, respectively, with a ΔE of 0.154 V. Furthermore, the peak currents increase nearly 100% compared with the electrode without modification. The process was more reversible compared with the electrode modified with only SWCNTs or PB. Cyclic voltammetry was used to characterize the modified electrode surface. The quantification of rutin was more sensitive with adsorptive stripping voltammetry than with anodic stripping voltammetry. Adsorption potential, adsorption time and pH were optimized based on the oxidation of rutin: Eads =–0.10 V, tads = 60 s, pH 3.0. The detection limit (3σ/b) was 0.01 μM and the relative standard derivation was 3%. The new sensor was used in the quantification of rutin in black tea, coffee and synthetic drink of tea with satisfactory results.
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ACKNOWLEDGMENTS Financial support by the Universidad de Ibagué (15-376-INT/16-416-INT) is gratefully acknowledged.
- adsorptive stripping voltammetry
- black tea
- Prussian blue
- synthetic tea drink