An amperometric biosensor based on peroxidases from Brassica napus for the determination of the total polyphenolic content in wine and tea samples

An amperometric biosensor based on peroxidases from Brassica napus hairy roots (PBHR) used to determine the total polyphenolic content in wine and tea samples is proposed by the first time The method employs carbon paste (CP) electrodes filled up with PBHR ferrocene (Fc) and multi-walled carbon nanotubes embedded in a mineral oil (MWCNT + MO) at a given composition (PBHR-Fc-MWCNT+ MO) The biosensor was covered externally with a dialysis membrane which was fixed at the electrode body side part with a Teflon laboratory film and an O-ring Calibration curves obtained from steady-state currents as a function of the concentration of a polyphenolic standard reference compound such as t-resveratrol (t-Res) or caffeic acid (CA) were then used to estimate the total polyphenolic content in real samples 1 he reproducibility and the repeatability were of 70% and 4 1% for t-Res (84% and 5 2% for CA) respectively showing a good biosensor performance The calibration curves were linear in a concentration range from 005 to 52 mg L-1 and 006 to 69 mg L-1 for t-Res and CA respectively The lowest polyphenolic compound concentration values measured experimentally for a signal to noise ratio of 3 1 were 0 023 mg L-1 and 0 020 mg L-1 for t-Res and CA respectively (C) 2010 Elsevier B V All rights reserved