m denotes extract and juices/wine weight,spectrophotometric method of phenolic depend on the weight of your target, volume after your pretreatment,V and also the conc. calculated from calibration cure.

I hav prepared extract from 10 gm of plants and yield is 1 gm..then i prepare stock of 1mg/ml for extract and standard also...so what will be the value of m.....for different concentration range from 25microgram to 200 microgram....???????????????

to calculate phenolic content

First we must performed calibration curve, then we calculate the linier regression concentration of gallic acid (as standard) vs absorbance.

y= bx + a, than replace the value of y with absorbance of samples, from this we have concentration of phenolic in samples . 

to get phenolic in mg/g samples (GAE) :

example : Absorbance = 0.441, LR y= 886.5714 x - 0.0175

0.441 = 886.5714x – 0.0175

X = 5.1716 x 10-4 g/100 ml

Phenolic conc = 5,1716 *10-4  g/ 100 ml                          X dilution factor 

                               weight of sample (g)/volume of sample(ml)

                           =  0,32322 g/g

phenolic conc = 323.22 mg/g sample GEA

Because you can make different concentration of plant extract in methanol, for example 0.1 or 1 mg/ml, it is necessary to report the cxv gallic acid) to the quantity of vegetal material, usually dry matter.

The amount of total phenolics is determined with the Folin- Ciocalteu reagent using Gallic acid as a standard and the total phenolics is expressed as mg/g gallic acid equivalents (GAE). Concentration of 0.01, 0.02, 0.03, 0.04 and 0.05 mg/ml of gallic acid are prepared in methanol. Concentration of 0.1 and 1mg/ml of plant extract is also prepared in methanol and 0.5ml of sample is introduced into test tubes and mixed with 2.5ml of a 10 fold dilute Folin- Ciocalteu reagent and 2ml of 7.5% sodium carbonate. The tubes are covered and allowed to stand for 30 minutes at room temperature and then the absorbance is at read at 760 nm on UV/VIs spectrophotometer. The Folin-Ciocalteu reagent is sensitive to reducing compounds including polyphenols, thereby producing a blue colour upon reaction. This blue colour is measured spectrophotometrically. The two attached file will provide you step by step laboratory protocol for TPC estimation.

In the previous answer, Yogesh gave a good alternative for phenols quantification. That's a routine analysis, easy to perform. However, the F-C assay usually overestimates the phenols concentration, since several chemical species besides phenols may reduce the molybdenum in the F-C reagent. In this way, if you will perform a comparative study, this technique is acceptable, but if you want to know accurately the phenolic content, you should opt for chromatographic techniques (HPLC-DAD/MS).

 for the quantification of total phenolic compounds used Folin-Ciocalteu reagent!

Hello. We use the methodology attached.

I feel that the answer given by Andi is the right answer to your question. I have carried out several fermentations too and used the classical method to determine the total phenolics by this method.

For determination of total phenolic compounds exist INPA and Embrapa methodologies that are used and to produce consistent results.

http://www.agencia.cnptia.embrapa.br/Repositorio/BPD_70_000gbz4ip6002wx5ok01dx9lc1zakvj8.pdf

total phenols is determined by Folin- Ciocalteu method 

You can determine total phenolics by Folin-Cioalteau method and the formula you are using is correct, as  v/m is the dilution factor. For liquid matrix you can use df = v/v. Please read the following references.

ESTIMACIÓN ESPECTROFOTOMÉTRICA DE FENOLES TOTALES EN ESPECIES DE LA FAMILIA MELASTOMATACEAE

TOTAL PHENOLICS ANTIOXIDANT ACTIVITY AND PHYTOCHEMICAL PROFILE OF SOME PLANTS FROM THE YOTOCO NATIONAL PROTECTED FOREST. VALLE DEL CAUCA, COLOMBIA

Use Folin-Ciocalteau method

Folin-Ciocalteau method

You can use the Folin-Ciocalteau method

First you need to build a standard curve with different concentrations of gallic acid and Folin-Ciocalteau. Then the equation of the standard curve can be calculated the concentration of polyphenols of our sample.

Dear Kumar,

The formular for total phenolic content determination is correct that is C=cxv/m

where c is the concentration obtained from calibration curve

            v is the volume of the extract used and

           m is the mass of the extract used.

Best wishes