Sørensen formol titration

In formol titration is a quantitative determination method for ammonium salts.

Since ammonium compounds not sufficiently acidic ( pKa 9.25 ) are to be determined directly with sodium hydroxide solution, one uses the fact that, for the addition of formaldehyde ( formalin ) only weakly basic urotropin ( pKa 5.2 ) arises:

The liberated by the above equilibrium reaction oxonium ions can be titrated with sodium hydroxide solution using phenolphthalein as an indicator. The formol titration is used for the determination of ammonium salts and organically bound nitrogen, after it has been transferred by means of the Kjeldahl digestion in water-soluble ammonium compounds. The formol titration was developed in 1907 by SPL Sørensen. Sørensen amino acids titrated with potassium hydroxide in the presence of formaldehyde.

Swell

• Harry Auterhoff: Textbook of Pharmaceutical Chemistry, 5th edition, Scientific Verlagsgesellschaft mbH Stuttgart, 1968.

• Detection reaction
• Titration