A novel flow injection amperometric method for sensitive determination of total antioxidant capacity at cupric-neocuproine complex modified MWCNT glassy carbon electrode


AYAZ S., ARDA A., DİLGİN Y., APAK M. R.

MICROCHIMICA ACTA, vol.189, no.4, 2022 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 189 Issue: 4
  • Publication Date: 2022
  • Doi Number: 10.1007/s00604-022-05271-z
  • Journal Name: MICROCHIMICA ACTA
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, Analytical Abstracts, Aqualine, Aquatic Science & Fisheries Abstracts (ASFA), Biotechnology Research Abstracts, Chemical Abstracts Core, Chimica, Communication Abstracts, EMBASE, Food Science & Technology Abstracts, MEDLINE, Metadex, Pollution Abstracts, Civil Engineering Abstracts
  • Keywords: Total antioxidant capacity, Chemically modified electrode, Multi-walled carbon nanotubes, Amperometry, Flow injection analysis, Copper(II)-neocuproine complex, ELECTROCHEMICAL METHODS, ION, POLYPHENOLS, CHEMISTRY, OXIDATION, ASSAYS, DPPH
  • Istanbul University Affiliated: No

Abstract

A novel amperometric method is presented for the determination of total antioxidant capacity in flow injection analysis (FIA) system using copper(II)-neocuproine complex modified on Nafion-functionalized multi-walled carbon nanotube-glassy carbon electrode ([Cu(Ncp)(2)(2+)]/Nf@f-MWCNT/GCE). Cyclic voltammetric studies showed that the modified electrode exhibits a very well-formed reversible redox couple for Cu(II)-/Cu(I)-complex. In addition, the [Cu(Ncp)(2)(2+)]/[Cu(Ncp)(2)(+)] redox pair shows very good electrocatalytic activity towards the oxidation of polyphenolic compounds (PPhCs) such as trolox, catechin, and quercetin due to the enhancement of the anodic peak current of the redox couple in the presence of these analytes. This electrocatalytic oxidation current at the [Cu(Ncp)(2)(2+)]/Nf@f-MWCNT/GCE was used for flow injection (FI) amperometric determination of PPhCs. FI amperometric-time curves recorded under optimized conditions (applied potential: + 0.6 V vs. Ag/AgCl/KCl(0.10 M), flow rate: 2 mL/min) showed that the proposed electrode had a wide linear range (LR) with a very low detection limit (LOD) for PPhCs. LR and LOD were 0.5-800 and 0.2 mu M for trolox, respectively and 0.50-250 and 0.14 mu M, respectively, for both quercetin and catechin. This sensitive method was successfully applied to the amperometric measurement of total antioxidant capacity (TAC) of some herbal teas, giving compatible results with the spectrophotometric CUPRAC method. The proposed method gave higher rank to fast-reacting antioxidants; it was equally precise but had a wider linear range and lower LOD than the spectrophotometric CUPRAC assay (e.g., LOD for ascorbic acid and gallic acid were 0.07 and 0.08 mu M, respectively), and similar electroanalytical methods using the CUPRAC reagent.