Development of Electrochemical HRP-MWCNT-Based Screen-Printed Biosensor for the Determination of Phenolic Compounds in Effluent from Washing Coffee Beans

Abstract

The present study demonstrates the development of an electrochemical HRP (horseradish peroxidase) - MWCNT (multiwalled carbon nanotube) based screen-printed disposable biosensor for the determination of phenolic compounds in effluent from washing coffee beans. The enzyme immobilization onto the surface of MWCNT was performed by covalent addition of glutaraldehyde cross-linked with BSA (bovine serum albumin) the performance of electrochemical method was compared with the reference method (Folin-Denis). The nanocomposite HRP-MWCNT was characterized by Scanning Electron Microscopy (SEM) and Spectroscopy Fourier Transform Infrared (FT-IR). Experimental parameters including pH, buffer concentration, H2 O2 concentration, amount of enzyme, BSA and glutaraldehyde have been optimized. The best conditions for the preparation of the disposable biosensor based HRP were: 25 μL solution of HRP (53 U mg-1 solid in 100 μL of water), 1.0 mg of BSA and 5 μL of glutaraldehyde (5% v/v). The proposed method had a sensitivity of 0.283 A L mol-1 with a linear response range from 20 to 32.5 μmol L-1, limits of detection and quantification of 0.16 μmol L-1 and 0.47 μmol L-1, respectively, using the square wave voltammetry. The results revealed that the biosensor had a good performance for the determination of phenolic compounds, when compared to other methods described in the literature. The proposed disposable biosensor was successfully applied for the determination of phenolic compounds in samples of wastewater from washing coffee beans, showing potential application in quality control of effluents.