Studies on Sialic Acid (Neuraminic Acid) in Cerebrospinal Fluid

Part 4: Methodology of Determination by Diphenylamine Reaction

抄録

We examined the diphenylamine reaction for determination of sialic acid in various samples of the human cerebrospinal fluid. It is recognized that the reaction is an unsatisfactory method for this purpose, except in estimating the acid content in cerebrospinal fluid protein or Niazi-State's fraction. In the cases trichloracetic acid is present in the samples or the reaction system, the blue or indigo-blue coloration tends to intensify, even when the main coloration is purple, and the extinction value is heightened in its presence, not only at 530mμ, but also at 660 mμ. It is necessary to investigate this tendency furthermore.
Though there is a possibility that some free sialic acid exists in the cerebrospinal fluid, it might be denied that free sialic acid exists in a quantity several times larger than protein-bound sialic acid.