The gas chromatographic determination of polyhydroxy monocarbonic acids obtained by oxygenation of-hexoses in aqueous alkaline solutions

A qualitative and quantitative method of analysis for the acidic reaction products resulting from the oxidation of Hexoses in aqueous alkaline solutions with oxygen is described. After the addition of hydrochloric acid to the aqueous reaction mixture, the sample is evaporated nearly to dryness. In addition to the unconverted hexoses, the residue consists, mainly. of the lactone structures of the acidic oxidation products. The residue is then dissolved either in pyridine or dimethylsulfoxide and silylated by means of a mixture of trimethylchlorosilane and hexamethyldisilazane. The silylated products are analysed by gas chromatography. Retention times have been determined on three stationary phases. A method is described for identifying an unknown compound by plotting the logarithms of the net retention times an two stationary phases of different polarity against each other. This method is applied to 25 compounds with different functional groups and varying molecular weights. A quantitative method has been developed based on calculated molar responses, relative to normal alkanes used as internal standards. The contribution of the primary and secondary silyl ether groups and the silyl ester group is determined from the molar responses of pure compounds.