Analysis of oligosaccharides using a liquid chromatography system and a chromatographic column in which the LC system and column's internal metal surface has been modified with a layer of inert material

A method of separating and analyzing one or more non-modified oligosaccharides with degree of polymerization 6 or higher from a sample, the method comprising:

• i. adding a fluorescent labeling reagent to the sample to label at least one of the one or more non-modified oligosaccharides with degree of polymerization 6 or higher to form a fluorescent labeled sample;
• ii. injecting the fluorescent labeled sample onto a hydrophilic interaction liquid chromatography (HILIC) column, wherein at least one component of the HILIC column comprises a fluid-contacting alkylsilyl coating on a metal surface;
• iii. flowing the injected sample through the HILIC column;
• iv. separating the injected sample into components, wherein at least one of the components comprises a fluorescent labeled non-modified oligosaccharide with degree of polymerization 6 or higher;
• and
• v. analyzing the at least one of the components with a UV detector and/or a fluorescence detector.