Lxvi. the Estimation of Carnosine in Muscle Extract-a

IN a recent communication [Hunter, 1921] a colorimetric method for the estimation of carnosine in muscle extract was generally outlined. This was based on a method of estimation of iminazoles devised by Koessler and Hanke [1919, 1]. This method depended on the coupling of carnosine with diazotised sulphanilic acid in alkaline solution to form an azo dye. The colour produced was measured against a standard solution of a mixture of Congo red and methyl-orange. Pure solutions of carnosine were found to react very satisfactorily, and in different extracts of the same muscles the colour values were consistent. The accuracy of the method could not be doubted, but the certainty that carnosine was responsible for the total colour production was called in question. The problem-of the extent to which carnosine is responsible for the production of the azo colour in muscle extracts-may be attacked in two ways: 1. By the elimination of all interfering substances. 2. By a direct method of confirming the carnosine content.