Tris and Tris Hydrochloride have been useful as buffers in a wide variety of biological systems. Uses include pH control in vitro and in vivo for body fluids and in buffering systems for electrophoresis applications. Tris has been used as a starting material for polymers, oxazolones (with carboxylic acids) and oxazolidines (with aldehydes). It can be used for the direct standardization of a strong acid solution; the equivalence point can be determined either potentiometrically or by use of a suitable indicator such as 3-(4-Dimethylamino-1-naphthylazo)-4-methoxybenzenesulfonic acid .