Folin & Ciocalteu's phenol reagent is used to determine protein concentrations between 1 to 100 μg/mL. However, the reagent exhibits a linear response to protein concentration up to 1000 μg/mL when used according to the instructions for kit Product No. TP0200.
The Folin-Ciocalteu (F-C) Assay was developed in 1927 for the measurement of tyrosine (1). The reagent consists of a mixture of sodium molybdate, sodium tungstate and other reagents. Upon reaction with phenols, it produces a blue color which absorbs at 765 nm.
The Folin–Ciocâlteu reagent (FCR) or Folin's phenol reagent or Folin–Denis reagent, also called the gallic acid equivalence method (GAE), is a mixture of phosphomolybdate and phosphotungstate used for the colorimetric in vitro assay of phenolic and polyphenolic antioxidants.
The Folin–Ciocalteu reagent which is a mixture of tungstates and molybdates works on the mechanism of oxidation–reduction reaction. The method strongly relies on the reduction of the mixture heteropolyphosphotungsates–molybdates by the phenolic compound which results in the formation of blue coloured chromogen.
