Hi,

have a look here

Article Complexometric determination of citric acid with copper

It is easy... Just titrate your sample with 0.1 N NaOH.

Citric acid: 0.1 N sodium hydroxide 1 ml ＝ 6.404 mg C6H8O7.

Work always in the presence of the indicator 2～3

drops of phenolphthalein solution.

Do the simple acid base titration using 0.1N NaOH solution and then apply this equation:

%acid ={(N x Vx 64) /( Wx1000)} x100

where N and V are the normality and volume of NaOH solution required to neutralize the solution. 64 is the equivalent weight of citric acid. W is the volume of solution (mL) you have taken for titration. Here the solution will be your fermentation broth.

About predicting the pH for the titration of citric acid with sodium hydroxide (or vice versa) ― or the pH of citric acid / sodium citrate(s) / sodium hydroxide solutions and buffers. ― Prediction depends on pH range:

(i) for approx. pH < 4.0 ― cf. my post at: https://www.researchgate.net/post/How-to-prepare-a-citric-acid-solution-of-pH-25-and-3-from-100-citric-acid-powder

(ii) for approx. 4.0 < pH < 5.5 ― cf. my posts at: https://www.researchgate.net/post/Why-the-pH-of-Citrate-buffer-increases-when-diluted-with-water

(iii) for approx. 5.5 < pH < 8.0 ― cf. my posts at: https://www.researchgate.net/post/Why-the-pH-of-Citrate-buffer-increases-when-diluted-with-water

(iv) for approx. pH > 8.0 ― cf. my posts at: https://www.researchgate.net/post/Why-the-pH-of-Citrate-buffer-increases-when-diluted-with-water

(v) for approx. pH > 9.0 ― cf. my posts at: https://www.researchgate.net/post/Why-the-pH-of-Citrate-buffer-increases-when-diluted-with-water

Dear Researcher,

Estimating citric acid concentration in a fermented sample through the titration method is a precise and commonly used analytical technique. The procedure involves the titration of the citric acid in your sample with a standard solution of a strong base, typically sodium hydroxide (NaOH). The following is a structured protocol for estimating citric acid using this method:

In summary, titration with NaOH, using phenolphthalein as an indicator, provides a reliable method for estimating citric acid concentration in fermented samples. Precise sample preparation, careful titration, and accurate calculations are key for obtaining reliable results.

Best regards,

This protocol list might provide further insights to address this issue.