Resumen de The Titration in the Kjeldahl Method of Nitrogen Determination: Base or Acid as Titrant?

Tadeusz Michalowski, Agustín García Asuero, Slawomir Wybraniec

• The final step of the Kjeldahl method of nitrogen determination in biological and other samples faces a dilemma: which titrant, whether acid or base, should be used for the titration of ammonia? To solve this problem, a simple calculation procedure, illustrating the manner of ammonia determination in this method, enables one to resolve this dilemma with the use of theory based on acid–base titration curves. It refers, in particular, to the choice of a strong acid (HCl, H2SO4) solution as a titrant for titration of the solution with H3BO3applied in a receiver flask following the distillation (NH3) step. The paper presents a clear illustration of the statement that “a good theory is the best practical tool”.