Salt Measurement in Food

How to Perform Salt, Sodium, Chloride, and Mineral Content Determinations

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Salt Measurement in Food
Salt Measurement in Food


Salt Determination Guide
Sodium and Salt Measurement Methods

Argentometric Titration of Chloride Ion

  • Method: Argentometric Cl- titration
  • Analyte type: Cl- ion
  • Analyte concentration range: ppm to 100%  

The most established titrimetric method to determine salt content is based on chloride measurement. Known as argentometric titration due to the use of silver nitrate (AgNO3) as the titrant, it remains in common use in food laboratories.

Silver ion (Ag+) precipitates from solution upon reaction with Cl- ion, and when all available chloride has been consumed by reaction with Ag+, the electrical potential in the titration vessel rises due to the accumulation of dissolved Ag+ ions in the sample solution. This indicates the endpoint of the titration, permitting calculation of the salt content (based on the assumption that all chloride in the sample was contributed by NaCl).

While chloride determination is rapid and typically does not require specialized equipment, the method will not account for sodium ions contributed by sources other than NaCl, as noted. This means that, while effective in many cases, it may not be suitable for every type of salt analysis.

An example of instrumentation is the METTLER TOLEDO Titrators.

Sodium Content Determination via Multiple Standard Addition (MSA)

  • Method: Sodium analysis in food using multiple standard addition
  • Analyte type: Na+ ion
  • Analyte concentration range: ppm to 100%

Multiple standard addition detects sodium within the sample matrix down to 0.1 mg/L (4.7•10−6 M). A small quantity of a sodium standard solution is dosed into the sample several times in succession, increasing its sodium concentration. The differences in potential resulting from the known volumes of the standard added are used to determine the sample’s intrinsic sodium concentration via an iterative evaluation algorithm based on the Nernst equation.

Importantly, MSA measurements can be performed near the detection limit and temperature effects can be compensated by the instrument for higher accuracy. An approximate sample concentration must be known prior to assay for optimal sample preparation and quantification.

An example of instrumentation is the METTLER TOLEDO Easy Na Sodium Analyzer or Excellence Titrators (including automation).

Thermometric Titration of Sodium Ion

  • Method: Thermometric Na+ titration
  • Analyte type: Na+ ion
  • Analyte concentration range: 100 ppm to 100%

Thermometric titration of sodium ion content is an alternative method to quantitate sodium in food products. Thermometric titration depends on the formation of elpasolite, NaK2AlF6, which is highly exothermic. The heat evolved can be registered by a highly resolved thermoprobe and used to infer the quantity of Na+ ion present in the original sample.

The reaction proceeds in the presence of ammonium fluoride or ammonium hydrogen difluoride (NH4F, NH4HF2), and requires an excess of potassium and aluminum. The toxicity of the former compounds, which are also highly corrosive, mean that appropriate safety precautions should be taken.

Suitable instrumentation for this analysis is the METTLER TOLEDO Excellence Titrators and Thermometric Electrode.

Direct Sodium Measurement

  • Method: Direct Na+ measurement with ISE
  • Analyte type: Na+ ion
  • Analyte concentration range: ppm to 100%

Sodium levels in food, typically in aqueous solution, can be determined directly using an ISE paired with a titrator or ion meter. Accuracy depends on use of a calibration curve to infer sample concentration under the assumption that the electrode’s response is the same for sample and standard solutions. A sodium standard dilution series is used for this purpose.

As with MSA, the detected potential is proportional to the activity of an ion in solution and hence its concentration. Following measurements, the paired instrument can automatically calculate the ion concentration of the sample and display the results.

Suitable instrumentation for this analysis is the METTLER TOLEDO Ion-meters with Ion-selective electrodes.

Other Methods of Salt Content Determination

Salt, sodium, ion and mineral content can also be measured via other techniques with differing levels of specificity. For applications such as the determination of total NaCl or mineral salts, special equipment is not always necessary.  

Additional methods that can be useful for determining chloride, sodium, or mineral content include:

Principle of measurement



Argentometric titration of chloride ion

35 ppm


Multiple Standard Addition (MSA)

< 1 ppm


Thermometric titration of sodium ion

100 ppm


Direct sodium measurement

< 1 ppm



Specific Laboratory Applications in Food Production
Specific Laboratory Applications in Food Production