Gas chromatography of methyl glycosides as their tri-methylsilyl ethers. The methanolysis and re-N-acetylation steps.

Gas chromatographic procedures for the analysis of carbohydrates in glyco-proteins frequently include methanolysis and re-N-acetylation steps. The usual methanolysis conditions were found to result in almost complete conversion of the methanolic HCl into methyl chloride. A neutral solution of methyl chloride in methanol was found capable of releasing fucose, sialic acid, and a portion of the galactose from alpha 1-acid glycoprotein. During the re-N-acetylation of the amino sugars O-acetylation of the alditols commonly employed as internal standards occurs. Addition of the standards after the re-N-acetylation step avoided the problem. The complete procedure for the determination of both neutral and amino sugars has been simplified to involve only one transfer step prior to final gas chromatography.