Determination of phenol content.

 Experiment

Object:

To determine the phenol content of given sample.

Reference: 

V.R. Singelton, R. Orthifer, R.M. Lamuela-Raventos, Analysis of total phenols and other oxidation substrates and antioxidants by means of Folin–Ciocalteu reagent Methods in Enzymology, 299 (1999), pp. 152-178

Requirement: 

Glassware: volumetric bottles, pipette ,cuvette, beakers, sieve

 Chemical: Folin-ciocalteu reagent, gallic acid,Sodim carbonate

Theory: 

A class of chemical compounds in organic chemistry which consist of a hydroxyl group (-OH) directly bonded to an aromatic hydrocarbon group is known as phenols or phenolics. Many phenolic compounds occur in nature and used in manufacturing of perfumes and flavors because of their pleasant odor.

Principle The entire phenolic compound is oxidized by folinciocalteu reagent. This reagent consists of mixture of phosphotungstic acid and posphomolybdic acid. This is reduced, during the oxidation of phenolic of substance into a mixture of blue molybdenum and tungsten oxide. The blue coloring product produced has a maximum absorbance about 750-760nm. It is proportional to the quantity of oxidised phenolic compound.  

     

 Procedure:

 1. To 0.2 mL of extract solution and 0.2 mL of Folin–Ciocalteu reagent were added and the contents mixed thoroughly. After 4 min, 1 mL of 15% Na2CO3 was added, and then the mixture was allowed to stand for 2 h at normal temperature. The absorbance was measured at 760 nm using a Spectro (Thermo Fisher Scientific, model 4001/4) spectrophotometer. The concentration of the total phenolics was calculated as mg of gallic acid equivalent by using an equation obtained from gallic acid calibration curve. The determination of total phenolic compounds in the fractions was carried out in triplicate and the results were averaged.. 

2. The absorbance was measured at 765nm using double beam UV-VIS spectrophotometer. 

3. The total phenolic content was determined from the linear equation of standard curve prepared with gallic acid. 

4. The content of total phenolic compound is expressed as mg/gallic acid equivalent (GAE) of dry extract, calculated using equation P= c×v /m Where, c=concentration of Gallic acid from curve v=volume of extract m=weight of extract.

 

Result : 

      Total phenol content was expressed as mg of GAE/gm of extract.