Abstract
About 20 years ago I reported a colour reaction given by arginine on the addition of α-naphtol and sodium hypochlorite to its alkaline solution. This reaction, which I recommended for the estimation of arginine, was notably improved by Weber by the use of hypobromite instead of hypochlorite. These methods have, however, a disadvantage in that α-naphtol and hypochlorite or hypobromite alone gradually produce a yellow colour which much interferes with the colouration given by arginine. In this commuication I am proposing the use of oxin instead of α-naphtol, as the former remains colourless on the mere addition of hypobromite.
