Dear Hussein,

Liquid Chromatography with Mass Spectrometric detection (LC-MS) is commonly used method to define the carbohydrate content of a an oligosaccharides. 

For similar analysis and more details on the protocol to be used, you may see the publications contained in the following links:

http://sciex.com/therapeutic-protein-characterization/carbohydrate-labeling-and-analysis

http://biopharmaspec.com/services/carbohydrate-characterisation/

Hoping this will be helpful,

Rafik

thanks Mr Rafik