Invasive bacterial meningitis caused by Neisseria meningitidis can be prevented by active immunization with meningococcal polysaccharide or polysaccharide-protein conjugate vaccines. In a tetravalent A/C/Y/W-135-DT meningococcal conjugate vaccine vial, or in a final formulated bulk, accurate identification and quantification of each polysaccharide are critical in product release. Determination of sialic acid serogroups (C, W-135, and Y) unambiguously is complex since all these serogroups contribute to the sialic acid monosaccharide peaks that overlap in the high-performance anion-exchange chromatography-pulsed amperometric detection (HPAEC-PAD). We report a quantification method that involves generation of monosaccharide standard plots for respective sugars mannosamine-6-phosphate, sialic acid, galactose- and glucose-derived from hydrolysis of mixtures of the four serogroups A, C, W, and Y reference polysaccharides. These plots were then used to obtain the unknown polysaccharide concentrations of A/C/Y/W-135 in vialed vaccine or from formulated final bulks. We also present our results of the HPAEC-PAD profiles on groups C, W-135, and Y polysaccharides when hydrolyzed individually and/or in mixtures to discuss the individual sialic acid peak contributions.