Gas chromatography of monosaccharides as O-isopropylidene derivatives. Analysis of hay, grass silage, and alkali-treated barley straw after mild and strong acid hydrolysis

Samples of hay, silage, untreated and ammonia-or alkali-treated barley straw were subjected to mild and strong acid hydrolysis, and the liberated monosaccharides were analysed by gas-liquid chromatography as their O-isopropylidene derivatives. From the mild acid hydrolysis, the total fructose content of the material and the amount of easily hydrolysed glucose were determined, allowing the content of non-structural carbohydrates to be estimated. In the same operation, the content of mannitol and arabinotol in the feed samples can be determined. From the strong acid hydrolysis, the total amounts of each aldose in the forage materials were determined.