The concept is comparing the absorbance of each sample instead of comparing the concentration. My idea is, the higher the absorbance, the higher the total phenolic content will be. Is it acceptable?
You should have a standard curve made of different dilutions from gallic acid, also you should have an internal standard (spiking) to measure recoveries( reagent and sample). It is not acceptable to depend on the absorbance that may give you an idea but not the real content that must belong to a certain expression such as mg/100 g FW gallic acid equivalent . please read my work attached for the method of total phenolics.
Good luck
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