This unit presents methods for assaying sialic acids, reducing sugars, and hexosamines. The BCA assay detects free reducing terminii in sugars released from glycoconjugates by appropriate treatments. Assays employing Ehrlich reagent (DMAB) detect hexosamines and N-acetylhexosamines, including a method for hydrolyzing the glycosidic linkages of the hexosamines and a method for re-N-acetylation. The TBA and DMB assays can be used to quantitate and fractionate free forms of many types of sialic acids. Techniques for liberating the sialic acids from the parent glycoconjugates are also provided.