Direct Potentiometric Measurement of NH4H2BO3 Following a Kjeldahl Distillation

Abstract

A method is described for the direct potentiometric measurement of NH₄H₂BO₃, following a Kjeldahl distillation. The NH₃ is distilled into a H₃BO₃ solution, and the activity of the NH₄H₂BO₃ is measured using a cation electrode sensitive to NH₄ ⁺ and an anion electrode sensitive to H₂BO₃. The method has been used to determine nitrogen in dried blood samples with assigned N values, and the potentiometric values agreed with the titrimetric results.