High-pressure liquid chromatography of sialic acids on a pellicular resin anion-exchange column with pulsed amperometric detection: a comparison with six other systems. A wide variety of different sialic acids have been reported in nature. Following their release and purification, detection and quantitation of these molecules is now possible by a number of techniques. We and others have previously reported high-pressure liquid chromatography separation of sialic acids with several different columns, elution methods, and detection techniques. We report here a new method for the separation of sialic acids at neutral pH on a Carbopac PA-1 anion-exchange column of pellicular resin, with pulsed amperometric detection following postcolumn addition of alkali. The major advantages of this system are the separation of a variety of sialic acids, sensitive detection (into the picomole range), and the relative ease of use for preparative purposes. Using a set of defined sialic acid standards, this method is compared and contrasted with six other HPLC methods previously described by us and by others. The advantages and disadvantages of each system are also addressed. In the final analysis, no single method is adequate to completely separate and quantitate all of the known sialic acids. However, used in appropriate combinations, these methods allow exploration of the biology of sialic acids in a manner heretofore not possible.