To obtain the concentration of polyphenols I made a calibration curve of GA. The equation was y = 0,0351x + 0,0098. I solved 10 gram of green tea in 200 ml of water for 2h at 50°C. Afterwards I took 40 ml of this extract and diluted it to 200 ml to color the textile for 45 min. Every 15 min I took a sample of 5 ml to examine it in the uv vis and I used 1 ml of the 5 ml for the Folic Ciocalteu method. How do i get to mg GA/g dry tea ?

my absorbance for example was 0,14 and 0,124

andrewEnlightened

# Total of polyphenols in tea extracts conc mg/l to mg/g dry tea?

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## John Wick

For the sample with an absorbance value of 0.14, you can perform the following calculation procedure:

from the gallic acid standard equation we can write:

x= (0.14-0.0098)/0.0351=3.7094 mg GAE/L coloring solution

x= 3.7094 *10-3 mg/1ml coloring solution

= 3.7094 *10-3 *200 mg/200 ml coloring solution

= 741.88034 mg/200 ml coloring solution OR:

= 741.88034 mg/40 ml tea extract

= 741.88034*5 mg/200 ml tea extract

= 3709.4 mg/200 ml tea extract

= 3709.4 mg/10 g tea

= 370.94 mgGAE/g green tea

Best wishes

## Andrew Pel

What is the amount of the reagent used?

Is the standard compound amount one ml as the solutions to be measured?

Please give more information so that I can measure the concentrations.

## avery

To help you calculate, can you clearly detail your method? You used which volume of extract, which volume of Ciocalteu folin and which volume of sodium carbonate.