What is an easy (i.e., home project) way to measure sodium in food?

For example, the nutritional label of a tahini brand that I often consume shows very little sodium (around 10mg/100g). I suspect the sodium content is much higher.

What is the chemical way to measure the salt content?


1 Answer 1


Sodium is a difficult ion to estimate at home.

Since most sodium salts are water-soluble, colorimetric or spectroscopic methods are often employed, both of which I assume are not within arms' reach.

Some alternatives:

  1. Speaking of sodium estimation in foodstuff, it is usually determined by Mohr's method which involves the precipitation titration of $\ce{Cl-}$ ions. This is done under the assumption that sodium is mainly present as sodium chloride. Additionally, it will also register $\ce{Cl-}$ from other chlorides, and hence may give an elevated reading. You might be able to do this at home. Here is a page to help you with the process.

    It is done in the presence of chromate ion ($\ce{CrO4^2-}$), and $\ce{Ag+}$ ions are added gradually. This precipitation happens initially:

    $$\ce{Ag+ + Cl- <=> AgCl(s)}$$

    When the solution runs out of $\ce{Cl-}$ ions, precipitation of the red-brown $\ce{Ag2CrO4}$ begins:

    $$\ce{Ag+ + CrO4^2- <=> Ag2CrO4(s)}$$

    This signals the end point.

  2. There are sodium ion meters, you can get them for ~300$.

  3. There is a volumetric estimation[1] for sodium directly, but it is not expedient to do it. It is based on the precipitation of sodium zinc uranyl acetate.


IMO it is difficult to do this as a home project, as it will require stuff that is not usually found at home to do it precisely.


[1] J. Am. Chem. Soc. 1931, 53, 9, 3288-3291 DOI: 10.1021/ja01360a011

  • $\begingroup$ Thank you! This is quite amazing. Do you think that the assumption that in food, most $\ce{Cl-}$ originates from table salt can be justified? $\endgroup$
    – Sleepster
    Commented May 17, 2019 at 14:14

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