Hi guys, may I ask for help to calculate phenolic content in my sample
Here's my step to do FC method:
- red pitaya peel 10 gram in 50 ml ethanol 50 % (and i got extract from here)
- i use 1,5 ml red pitaya peel extract + 2 ml folin ciocalteu + 2,5 ml Na2CO3 7,5 %
the absorbance is 0,714 with gallic acid curve is y=0,0131x + 0,0411
Thank you for your help
Procedure available in Ayurvedic pharmacopeia of India. And Indian pharmacopeia
We need you to provide the unit of concentration of gallic acid used to build the curve. Otherwise we cannot calculate it.
The total phenolic contents (TPC) can be calculated by the Folin-Ciocalteu colorimetric method based on the oxidation-reduction reaction by using gallic acid as standard since it is less expensive and available in pure form.
From your straight line equation make x the subject formula I.e x = y-0.0411/0.0131. Then y is the average absorbance of your sample and calculate for x which is the phenolic content of your sample expressed as grams per Gallic acid equivalent or grams per tannic acid equivalent depending on the one you used for the calibration curve.
Total polyphenols is evaluated by spectrophotometry using Folin-Ciocalteu reagent as described in our recent work. The standard solution is prepared using a freshly prepared equeous solution of ascorbic acid.
As the information given by you, the concentration of your sample is 0.3 g in 1.5 ml which gives absorbance 0.714
For example, just imagine, your standard curve is made of the following concentration:
10 ug, 20 ug, 30 ug, 40 ug, 50 ug and their absorbance were 0.5, 0.6, 0.7, 0.8, and 0.9 respectively.
Increase in concentration results increase in the absorbance.
If 30 ug of GA gives absorbance 0.7, then you can easily depict the concentration of GA (x) in your sample from the given absorbance (0.714).
So as per calculation, 0.3 g of the sample contains 30.6 ug of GA (in 1.5 ml) and 1.02 mg of GA in 50 ml of solution.
Hope this will be helpful to you.
I hope that the mentioned web-links and paper would be useful.
antioxidants-08-00254-s001.pdf
https://pubs.rsc.org/en/content/articlelanding/2013/ay/c3ay41125g/unauth#!divAbstract
https://doi.org/10.3390/molecules18066852
https://doi.org/10.1016/j.foodchem.2004.12.004
doi: 10.3390/plants8040096
doi:10.1088/1755-1315/299/1/012021
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