Identifying Carbohydrates and Lipids - (Oct/22/2008 )
I'm new to the BioForum, so hopefully this topic is in the right forum. My question is, if you have a mixture of carbohydrates, is there any way to separate them out and identify them? I know that with proteins, you could run your sample through an SDS-PAGE gel, excise the bands, and send them for a mass spectrometry analysis. Is there any technique that can be used to specifically determine the identify of a carbohydrate? I also have the same question in regards to lipids. Thanks to any responses in advance!
Carbos: chromatographic techs exist (paper, TLC and HPLC). Polarimetry is a fairly good tech too. Best to identify a purified fraction rather than a sugar cocktail. Enzymatic methods are available that give aceptable specificity. Finally, capillary electrophoresis. You'd need to calibrate any method against standards of course. Carbos separation is tricky due to similar molecular sizes and physiochemical properties.
Lipids: a bit easier (?). Separate by solvent extraction in specific organic solvent then detection by adsorption chromatography, TLC and gas chromatography.
Fully to characterize the lipid content of a sample might involve a lot of small scale purifications but well established methods do exist. What sample matrix are you working on? Clinical labs are well poised to analyse cholesterol & triglycerides. Same for glucose. Some of the more esoteric compounds would need more imaginative work.
Various flavors of mass spec and NMR are also used to identify carbohydrates and the linkages joining the monosaccharides. There are places that specialize in such analysis, like the Complex Carbohydrate Research Center at the University of Georgia.