In our method, 100 µL of plant extract at 1.5 mg/mL concentration is mixed with 200 µL of Folin–Ciocalteu reagent (ratio 1:2), followed by dilution with 2 mL of water and 1 mL of Na₂CO₃ solution (Na2CO3 : H2O 20:80 w/v). For a 1 mg/mL extract concentration, the same volume (100 µL) and ratio (1:2) can be maintained for optimal Total Phenolics Content estimation, ensuring sufficient reactivity and absorbance within the standard curve range.

A common approach to estimating total phenolic content using the Folin-Ciocalteu (FC) reagent is diluting the plant extract. The recommended ratio typically ranges from 1:10 to 1:20 (extract to FC reagent).

Here’s a general guideline:

Adjustments may be necessary based on the specific characteristics of the extract and the sensitivity of your assay, so it’s always good to perform preliminary tests.

We using, for total phenolic content estimation, 50 µL of 1 mg/mL plant extract & volume is madeup to 1 mL with distilled water, followed by the addition of 0.5 mL of 1N FC reagent and 2.5 mL of 5% sodium carbonate in a 1:10:50 ratio. The mixture is vortexed, incubated in the dark at room temperature for 40 mins, and the absorbance is measured at 725 nm.

Hi,

You may use the web tool to calculate

https://www.alfa-chemistry.com/solution-dilution-calculator.htm

https://www.alfa-chemistry.com/mass-molarity-calculator.htm

I used the ratio (1:1) and it worked perfectly

You can see the results and the method here:

https://www.researchgate.net/publication/369949412_Effect_of_Rosemary_and_Marjoram_Extracts_on_Oxidative_Stability_of_Refined_Sunflower_Oil