Good afternoon
Question is related to phenolic compounds. The method was performed as follows:
- First, 20 ml of ethanol were added to 0.1 g of dry sample. Second, the extract (0.1 ml) was used to react with Folin Ciocalteu and Na2CO3. Finally, the absorbance was measured at 725 nm (0.96).
- An equation from a standard curve of gallic acid was used: y = 3.6554x + 0.0893. Where y is Absorbance and x is gallic acid concentration (mg/ml).
- The result was obtained as follows: 0.96 = 3.6554x + 0.0893 ---> x = 0.238 mg/ml. But, it must be multiplied by dilution factor which is (if I'm not wrong) 20 ml / 0.1 g = 200.
- Finally, the total phenolic content is: 0.238 x 200 = 47.63 mg/ml.
How do I express this in mg/g of dry weight?
Thank you very much in advance.
to expess in mg/g of dry matter you have to use calibration curve
you will have un equation Y=ax+b
to calculate the concentration : (c)=Absorbance/a
you will find the result following your calibration curve(unit) then you multiply The extraction volume to return to the mg / g of dry matter.
I hope that I have helped you.Good continuation and good luck for the rest
I think you can first work out the absolute amount of gallic acid (phenolic cpds) in your 0.1 ml sample, that is [2.38 mg]. You have 20 mL of total volume therefore the total absolute amount = 2.38 mg x 20 = [47.6 mg]. To express mg/dry wt = 47.6mg/0.1g = 476 mg/g. Hope it helps.
One more question, is it ok to obtain a quantity higher than 100 mg/g?
Thank you very much for your answers.
If your matrix is very rich in polyphenols , you can find hight content Which may even exceed 100mg/g of dry matter
good continuation
If it was a sol, for exemple you did leaching or extraction, you have to convert the unity from mg/l to mg/Kg, so usually we use this method:
for example (leaching):
100g ->1L
the concentration of nitrite is : 2mg/l
so you do 2/100 (mg/g), after that you get 0.02*1000 to have 20mg(nitrite)/kg sol
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