Sialic Acid (N-Acetylneuraminic Acid) in Human Serum

A simple spectrophotometric method is described for the sialic acids which utilizes the reaction with resorcinol and extraction with butyl acetate-n-butanol as a solvent. Normal values for adults, utilizing N-acetylneuraminic acid as a standard, were found to be 60 ± 10.4 mg./100 ml. Values for newborn babies averaged 40.4 ± 5.7. Similar values were found for specimens from 2-month-old infants to 27-year-old adults. Higher values were noted in the case of rickets, severe burns, rheumatic dis-ease, and tuberculosis. THERE ARE numerous procedures for the quantitative determination of hexoses and hexosamines, but few exist for sialic acids. Considering that these three carbohydrate groups, together with proteins compose the main part of glycoproteins, it seemed worthwhile to present our experiences with a technic for tile determination of sialic acid (N-acetylneuraminic acid) in human serum, which is fairly simple and precise enough to be used for clinical purposes. Method and Materia’s The principle employed involves precipitation of serum glycopro-teins by 95 % ethanol at 00; Hydrolysis and the reaction of N-acetyl-neuraminic acid (NANA) by a HC1-cupric-resorcinol reagent; extrac-tion of the colored component by butyl acetate; and the measurement of the color intensity at 580 m. Apparatus Our measurements were made with a spectrophotometer (Zeiss Model M 42*) with 2 cm. X 10 ml. cuvets. If a spectrophotometer is no