How do I calculate the total polyphenol content in mg GAE/g. from the extract?
Following is my data:
Sample extract(stock): 0.01 gram in 1 ml
Equation: y= 0.0078x - 0.0679, R2 = 0.9969
Absorbance: Sample was serially diluted-
1000(µg/ml)=0.598
500(µg/ml)= 0.296
250(µg/ml)=0.127
125(µg/ml)=0.063
62.5(µg/ml)= 0.026
What is the dilution factor here? How can I calculate x in the form of mg GAE/g?
Can anyone please help me?
Prepare Standards: gallic acid (50ug-400ug)
Plot the absorbance values of the gallic acid standards against their concentrations to create a standard curve (e.g., Absorbance vs. Concentration).
Use the standard curve equation (y = mx + b) to determine the phenolic content of your plant extract samples from their absorbance values.
There a number of things to clarify before we can answer your questions:
What did you use to do the standard curve? For you to get the equation you should have done a standard curve which values did you use? When you say sample was serially diluted is it the standard sample or the extract? What was the absorbance reading for your 0.01g/ ml sample extract? This sample extract is most likely to have been diluted as it will be way above you highest value of the standard samples, you need to check the dilution factor, looking at the figures it is most likely to be a x10 sample extract dilution.
Then: you plot your standard curve to get the equation assuming that there was a blank used which will be 0 micrograms concentration and 0.0 absorbance thereby forcing you trendline to pass through the origin. You will get a new equation and R-square values. Then use this equation to calculate x, then multiply the value by dilution factor to get ug GAE/ml of sample extract.
I hope this helps.
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