Sugar acetates quantitative analysis

Having noted the large proportions of volatile adds present in milk fermented by the aid of commercial cultures, it has been observed that the total weight of adds formed always exceeds that of the sugar destroyed, a fact which plainly indicates that the adds do not come solely from the sugar, but also from the protein material. A quantitative analysis has revealed the presence of succinic, malic and acetic acids. It is only with Bertrand s ferment and Boucard s Lacteol that lactic add has been obtained. 

Water analysis of liquids was by Karl Fischer titration. Liquids were analyzed by GC for qualitative or semi-quantitative characterization. Quantitative analysis of selected liquid components was performed by HPLC. The sample was prepared by diluting it with two parts water to cause phase separation of pyrolytic lignin. Simple sugars, anhydrosugars, and other lower molecular weight components such as acetic acid and hydroxyacetaldehyde remain in the aqueous phase. 

Other reagents suitable for paper chromatography are also applicable to TLC (Nos. 10,21,134,159,178,234, 255) and some other reagents containing periodic acid. Of these, iodine vapor [18] has the most universal application since it detects a variety of carbohydrate derivatives including the free sugars, partially and fully substituted methyl and benzyl ethers, esters and acetals. Although iodine is less sensitive than suKuric acid, it is non-destructive in the short exposure time required (5—20 min) and can therefore be used to detect components on preparative plates or for quantitative analysis. The adsorbed iodine disappears when the plate is exposed to the air. 

With the advent of new, more versatile and more robust LC-MS interfaces based on atmospheric-pressure ionization, the use of thermospray will rapidly diminish. However, the above-mentioned applications in sugar analysis as well as a large number of other applications in organic ion analysis such as phenoxy-acetic acids [128], quaternary ammonium pesticides [129, 130], anionic surfactants [131, 132], sulfated azo dyes [133, 134], sulfonamides [135], and ff-lactam antibiotics [136, 137] have proved the potential of this coupling technique in qualitative and quantitative analysis. 

It is apparent from the foregoing that a more specific method for the determination of xylan would be desirable. To this end, the determination of xylose, after acid hydrolysis of the polysaccharide material, has been attempted. Xylose may be oxidized to xylonic acid which can be precipitated with cadmium bromide as the double salt, but the precipitation is not quantitative. Xylose forms an insoluble, crystalline di-O-benzylidene dimethyl acetal which permits identification in the presence of other sugars, but the necessity for anhydrous reaction conditions precludes the adaptation of this method to ordinary analysis. AVise and Ratliff prepared this derivative of both d- and L-xylose, as well as analogous derivatives from other aromatic aldehydes, and concluded that, with either the di-O-benzylidene or the di-O-(p-isopropylbenzylidene) dimethyl acetal, an excellent, highly specific, qualitative test was available for d- or n-xylose. 

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