I need help in determining my TPC. I used Gallic acid to prepare a calibration curve with conc ranging from 1.5-10 mg/L and I obtained for my extract 60 mg GAE/L from the curve, but now I'm not sure of how to convert this value to mg GAE /g. I used 15 ul of my standard/extract, 240 ul water, 15 ul FCR, 30ul Na2SO3 making a final assay volume of 300 ul.
The same thing to convert from umole TE(trolox equiv.)/L to umole TE/g.
Thanks!
As you know, the total phenolic content in mg GAE/100g as the following
0.5 ml extract equivalent 50 mg of sample
so 20.03µg/ml = 20,03 ug / 100mg
0.203 mg / g
= 20.3mg /100g
Therefore:Calculated value (from mg GAE/L to mg GAE/g) for the extract obtained in 4 h extraction with 60% ethanol, hydrolyzed at 80 °C
look at :
1-M. P. Kähkönen, A. I. Hopia, H. J. Vuorela, J.-P. Rauha, J. Agric. Food Chem., 47(10), 3954 (1999).
2-A. Wojdylo, J. Oszmiańsky, R. Czemerys, Food Chem., 105, 940 (2007).
3-D. Modnicki, M. Balcerek, Herba Pol., 55(1), 35 (2009).
for more formation please look at
http://www.cellulosechemtechnol.ro/pdf/CCT3-4(2014)/p.265-273.pdf
Dear miss Antonucci
To express TPC from mg/L to mg/g is necessary to know the quantity of dry sample diluted in a certain solvent (Plant sample extraction). After this, you determined TPC by adding 240 uL H2O, 15 uL FCR and 30 uL Na2SO3 to 15 uL of extract. Finally, you obtained 60 mg GAE/L using your standard curve.
For example,
1 g of dry sample was extracted in 20 ml of water for 60 min at room temperature. Solution was centrifuged at 5000 rpm and 1.5 uL of extract was added to 240 uL H2O, 15 uL FCR and 30 uL Na2SO3. Finally, 60 mg GAE/L was obtained through a standard curve.
To express 60 mg GAE/L in mg GAE/g, first you must use values of extraction: 1 g of dry sample in 20 ml of water. Concentration for this solution is found as follows:
* 1g / 20 ml ------> 0.05 g/ml ------> 50 g/L (There are 50 g of dry sample in 1L H2O).
* Now, you replace this value in 60 mg GAE/L ------> 60 mg GAE / 50 g.
* Finally, 60 mg GAE/L are expressed as 1.2 mg GAE/g dry weight.
I hope this helps. Regards.
To express TPC from mg/L to mg/g
The total phenolic content was calculated as gallic acid equivalent (GAE) by the following equation:
T =Cx V/M .
T is the total phenolic content in mg·g–1 of the extracts as
GAE, C is the concentration of gallic acid established
from the calibration curve in mg·ml–1, V is the volume of
the extract solution in ml and M is the weight of the extract
in g
I hope this helps. Regards.
for more formation please look at
Dear Antonucci,
May i know the concentration of the extract you used?
Hi guys, I have a question.
I have extracted 0.5 g biomass using 5 mL of solvent. From this, 40 uL were used to calculate the total phenolics content (TPC).
40 uL extract + 1560 uL distilled water + 100 uL Folin reagent + 300 uL Na2CO3. Using absorbance of 725 nm, and based on gallic acid calibration curve, we have only got 25 mg/L GAE. How can I convert it to mg/g biomass?
Does the dilution using 1560 uL distilled water affect the calculations?
Thank you.
Dear Wan Mohd Asyraf Wan Mahmood
1560 μl of distilled water added does not affect the calculations.
Dear Amel Amrani,
Is my calculations correct?
T = 0.025 mg/mL x 0.04 mL/0.5 g = 0.002 mg/g GAE
0.5g/5mL------>0.1g/mL------>0.1g/1000ul
40uLcontain 0.004g
T = 0.025 mg/mL x 0.04 mL/0.004 g = 0.25 mg/g GAE
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