Folin-Ciocalteau Reagent for Polyphenolic Assay

Abstract

The Folin-Ciocalteau (F-C) method of assay is the simplest method available for the measurement of phenolic content in products. It is a development of Folin Denis reagent used in the early 19th century for the determination of tyrosine in proteins [1]. F-C reagent can be prepared by dissolving 100 g sodium tungstate (VI) dihydrate and 25 g sodium molybdate (VI) dihydrate with 700 ml distilled water, 100 ml concentrated hydrochloric acid, and 50 ml of 85% phosphoric acid to which is added 150 g of lithium sulphate hydrate. This reagent is very stable if protected from reductants and even when diluted if protected from light. For many years now, the F-C method of assay has been in use as a measure of polyphenol in natural products, and the basic mechanism is an oxidation/ reduction reaction with the phenolic group being oxidized and the metal ion reduced. Chemistry controlling the reaction with Folin-Ciocalteau reagentFolin-Ciocalteau phenol reagent consists of a mixture of the heteropoly acids, phosphomolybdic and phosphotungstic acids in which the molybdenum and the tungsten are in the 6+ oxidation state. On reaction with a reductant, the molybdenum blue and the tungsten blue are formed and the mean oxidation state of the metals is between 5 and 6. Na 2 WO 4 /Na 2 MO 4 yellow⇒ (Phenol-MoW 11 O 40 ) -4 blue Mo +6 (yellow) + e -1 ⇒ Mo +5 (blue) Mo +5 + e -1 ⇒ Mo +4 (blue) ØOH ⇒ ØO • + H +1The above reaction is slow at acidic pH and faster when basic. It is very sensitive, precise but lack specificity. Singleton and Rossi [2] further improved the method with a molybdotungstophosphoric heteropolyanion reagent that reduced polyphenols more specifically with the λ max for the product at 765 nm.To achieve meaningful, reliable and predictable results, some conditions such as proper volume ratio, optimal reaction time, and temperature for colour development, standard optical density, and use of a particular reference-standard polyphenol are required.The improved method F-C reagent can be used by two principal procedures for the measurement of polyphenolic content i.e. as dual reagent [2,3] and as single reagent [4,5].

Effects of Olive Leaf and Marigold Extracts on the Utilization of Nutrients and on Bone Mineralization using Two Different Oil Sources in Broilers

“…Total phenol content was determined using modified the Folin-Ciocaltau polyphenolic assay (Agbor et al, 2014;Singleton and Rossi., 1965), flavonoids by the AlCl 3 colorimetric method (Lin and Tang, 2007), chlorophylls by the method described by Vernon (1960), carotenoid as described by Biehler et al (2010), and flavanols using the 4-dimethylaminocinnamaldehyde assay as proposed by Wallace and Giusti (2010). The content of oleuropein was analyzed by HPLC following method COI/T.…”

<I>Artemia salina</I> Lethality and Histopathological Studies of Siam Weed, <I>Chromolaena odorata</I>

“…The total phenolic compound was determined using Folin-Ciocalteu reagent according to Jiraungkoorskul 20 and Agbor et al, 21 with modifications. Briefly, the test was done in triplicate, the 50 µl of the aqueous and ethanolic extract (2.5 mg/ml) in each time (1, 3, 5 and 24 hours) was mixed with 250 µl of 10% Folin-Ciocalteu phenol reagent in distilled water and 200 µl of 0.7 M sodium carbonate then added distilled water up to 5 ml and incubated at room temperature for 2 hours in the dark condition.…”

Evaluation of Standards and Interfering Compounds in the Determination of Phenolics by Folin-Ciocalteu Assay Method for Effective Bioprocessing of Biomass

“…FT-IR and Raman Spectroscopy require chemometrics for data analysis and interpretation [20]. F-C assay using UV-VIS is the simplest and economic technique for the measurement of phenolics [21]. In F-C method, the phenolics are reacted with F-C reagents and the reduced blue color metal complex solution is measured using UV-VIS at specified wavelength.…”