A simple process for estimating amino- or other basic groups in amino-acids etc.: the “glacial acetic acid” method

A STUDY of the titration curves of the amino-acids [Harris, 1923, 1] shows that their amino-groups are quantitatively converted into their hydrochlorides (or similar acid salt) when the PH is reduced to a value approaching 0 5 to 0 (for titration constants of certain individual amino-acids, cf. Harris [1923, 2, 3; 1929, 1]; In other words, provided that one starts with the free amino-acid and titrates it to a sufficiently acid end-point the amount of acid entering into combination with it is then stoichiometrically equal to its amino-or other basic groups. R(NH2) +xHCl -+ R(NH3Cl)X.