Gas chromatographic separation of aldonic acids as trimethylsilyl derivatives

The separation of trimethylsilyl derivatives of various aldono-1,4-lactones was studied by gas chromatography on a large number of stationary phases. These lactones which are conveniently prepared by evaporating sample solutions containing aldonic acids in the presence of hydrochloric acid, gave rise to single chromatographic peaks. Under other working conditions e.g. by evaporation in the presence of calcium chloride, three peaks can be recorded for each aldonic acid. These were identified by their mass spectra as the fully trimethylsubstituted derivatives of the 1,4-lactone, 1,5-lactone and the trimethylsilyl ester