Development of a double-monitoring method for the determination of total antioxidant capacity as ascorbic acid equivalent using CUPRAC assay with RP-HPLC and digital image-based colorimetric detection

Borahan T., Girgin A., Atsever N., Zaman B. T., Chormey D. S., BAKIRDERE S.

EUROPEAN FOOD RESEARCH AND TECHNOLOGY, vol.248, no.3, pp.707-713, 2022 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 248 Issue: 3
  • Publication Date: 2022
  • Doi Number: 10.1007/s00217-021-03923-7
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, ABI/INFORM, Agricultural & Environmental Science Database, Aquatic Science & Fisheries Abstracts (ASFA), BIOSIS, Biotechnology Research Abstracts, CAB Abstracts, Chemical Abstracts Core, Compendex, Food Science & Technology Abstracts, Hospitality & Tourism Complete, Hospitality & Tourism Index, Veterinary Science Database
  • Page Numbers: pp.707-713
  • Keywords: CUPRAC, HPLC-UV, Ascorbic acid, Smartphone, Digital image, Apple juice
  • Yıldız Technical University Affiliated: Yes


This study was aimed at developing a double-monitoring detection system for measuring the TAC (total antioxidant capacity) of apple juice samples. The conventional CUPRAC (cupric ion reducing antioxidant capacity) assay was coupled to high-performance liquid chromatography-ultraviolet (HPLC-UV) and digital image-based colorimetric detection systems. In the CUPRAC assay, a chromogenic copper(II)-neocuproine (Cu(II)-Nc) reagent was used to oxidize the antioxidants, which is further reduced by the antioxidants to a yellow-colored copper(I)-neocuproine (Cu(I)-Nc) chelate having maximum absorption at 450 nm. The yellow-colored samples were measured by HPLC-UV and digital image-based colorimetric detection systems. Parameters of the HPLC-UV system were optimized to obtain a sharp and transient peak at 450 nm analytical wavelength. Under the optimum experimental conditions, the detection limits calculated for ascorbic acid using the HPLC-UV and digital image-based colorimetric detection systems were 0.28 and 0.70 mg/L, respectively. Satisfactory results (95.6-102%) were calculated for apple juice samples spiked at different concentrations for both detection systems, and very low (< 5.0%) percent relative standard deviation values were recorded. The TAC value for ascorbic acid equivalent in apple juice sample was found as 131 +/- 0.1 mg/L using the HPLC-UV system.