Studies on Sialic Acid (Neuraminic Acid) in Cerebrospinal Fluid

We studied the direct Ehrlich reaction as a method for determination of sialic acid in human cerebrospinal fluid. This reaction is clearly less useful as compared with Bial's reaction or the diphenylamine reaction. And it is not suitable for protein-free samples containing trichloracetic acid. But it is expected that the reaction may be serviceable in determining the sialic acid content in samples of the whole cerebrospinal fluid or the protein-free cerebrospinal fluid containing no trichloracetic acid. The existence of a large amount of the free sialic acid as compared with the protein-bound sialic acid in the cerebrospinal fluid is denied.