title: Application of the 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation assay to a flow injection system for the evaluation of antioxidant activity of some pure compounds and beverages.
abstract: The 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS(*)(+)) assay was adapted to a flow injection (FI) system to obtain a sensitive and rapid technique for the monitoring of antioxidant activity of pure compounds and complex matrixes, such as beverages and food extracts. The FI system includes a HPLC pump that flows the mobile phase (a solution of ABTS(*)(+) in ethanol) through a 20 microL loop injector, a single bead string reactor filled with acid-washed silanized beads, a delay coil and a photodiode array UV-visible detector. The technique was very sensitive, with limits of detection and of quantification of 4.14 and 9.29 micromol of Trolox/L, respectively, and demonstrated high repeatability and reproducibility. The proposed technique was then applied to the evaluation of the antioxidant activity of some pure compounds, demonstrating good agreement with published data obtained by the original spectrophotometric ABTS(*)(+) assay. Finally, the total antioxidant activity of 10 beverages was determined by both the proposed and the original method. The values ranged from 0.09 mmol L(-)(1) for cola to 49.24 mmol L(-)(1) for espresso coffee and did not result significantly different from those obtained by the original spectrophotometric ABTS(*)(+) assay (Student's paired t-test: t = 1.4074, p = 0.1929). In conclusion, the proposed FI technique seems suitable for the direct, rapid and reliable monitoring of total antioxidant activity of pure compounds and beverages and, due to the ability to operate in continuous, it allows the analysis of about 30 samples h(-)(1) making the assay particularly suitable for large screening of total antioxidant activity in food samples.
authors.affiliation: Department of Public Health, University of Parma, Via Volturno, 39, Italy. mailnico@nemo.unipr.it
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Pellegrini
authors.forename: Daniele
authors.initials: D
authors.lastname: Del Rio
authors.forename: Barbara
authors.initials: B
authors.lastname: Colombi
authors.forename: Marta
authors.initials: M
authors.lastname: Bianchi
authors.forename: Furio
authors.initials: F
authors.lastname: Brighenti
mesh_terms: D000975:Antioxidants / Q000032:analysis* / Q000737:chemistry; D001515:Beer / Q000032:analysis; D052160:Benzothiazoles; D001628:Beverages / Q000032:analysis*; D002253:Carbonated Beverages / Q000032:analysis; D002412:Cations; D002839:Chromans / Q000032:analysis; D002957:Citrus; D003069:Coffee / Q000737:chemistry; D017022:Flow Injection Analysis; D005609:Free Radicals / Q000737:chemistry; D005638:Fruit / Q000737:chemistry; D007202:Indicators and Reagents; D011786:Quality Control; D012680:Sensitivity and Specificity; D012996:Solutions; D013053:Spectrophotometry; D013451:Sulfonic Acids / Q000737:chemistry; D013662:Tea / Q000737:chemistry
chemical_list: D000975:Antioxidants; D052160:Benzothiazoles; D002412:Cations; D002839:Chromans; D003069:Coffee; D005609:Free Radicals; D007202:Indicators and Reagents; D012996:Solutions; D013451:Sulfonic Acids; D013662:Tea; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid