Direct determination of Sodium by Thermometric Titration

The Titrotherm 859 now offers a rapid, direct titration method for sodium. It does not require the time-consuming sample preparation needed for Atomic Adsorption Spectroscopy (AAS) or Inductively Coupled Plasma Spectrometry (ICP).

Since sodium is determined directly, it avoids the errors implicit in indirect methods (such as determining the chloride content in foods, and then relating that to the sodium content). The method can be applied to the determination of sodium in foodstuffs such as soups and sauces, as well as the commercial production of a wide variety of sodium salts.

The titration (application notes H-061 and H-062) is based on the exothermic formation of insoluble NaK₂AlF₆ (elpasolite). A standardized solution of aluminium containing a stoichiometric excess of potassium is used as titrant, with the sample only requiring conditioning in presence of ammonium hydrogen difluoride at pH 3.