2.3.2. Determination of total phenolic content (TPC)

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TPC was calculated in the methanolic extracts, according to

the Folin–Ciocalteu method with slight modifications (Jaramillo-

Flores et al., 2003). A 100 μL aliquot of methanolic extracts was

mixed with 900 μL of Folin–Ciocalteu phenol reagent (diluted 1:10

with water) and was allowed to stand for 5 min at room temperature;

0.75 mL of 7% sodium bicarbonate solution was added to

the mixture and vortexed for 30 s, and allowed to stand for 90 min at

room temperature. The absorbance was measured at 725 nm using a

spectrophotometer (Shimadzu, UV-2450, Tokyo, Japan). A calibration

curve of gallic acid (ranging from 0 to 1.00 mg/mL) was prepared

and tested under similar conditions. All values were expressed as

mean (mg of gallic acid equivalents/g of fresh weight)±SD for 3

replications.

mg/100 gm dw

= Optical Density X volume up (ml ethanol or Me-oH ) X 100 / slope (from GA standard curve X sample weight (mg or gm ) X 100

thanks Mr Abdo for your response and the material provided to my question

Your welcome , if you want more details don't hesitate

I have the same problem!!Volume up is 100 μL in this case? And the sample weight term refers to the weight before extraction? or the mg that you had in the particular C for example C=20 mg\ml is the price that gives an ABS of 1.500 and gives 0,850 mg TPC \mg DW of sample