Simple sugars, oligosaccharides, polysaccharides, and their derivatives, including the methyl ethers with free or potentially free reducing groups, give an orangeyellow color w-hen treated with phenol and concentrated sulfuric acid. The reaction is sensitive and the color is stable. By use of this phenol-sulfuric acid reaction, a method has been developed to determine submicro amounts of sugars...

The publications on Kjeldahl’s method for determining nitrogen that have appeared since Kjeldahl’s (1) original paper in 1883 perhaps outnumber those on any other analytical method in the same period of time.1 The diversity of papers is attributable to the immense usefulness of the method, to its need for modifications for applications to various types of organic and inorganic compounds, and to...

Application of neural network for modeling the saccharification of biomass by concentrated acid hydrolysis has been investigated. Due to a more complex and unknown kinetics of the investigated reaction, the proposed approach based on application of neural networks is an efficient and accurate tool to solve modeling problem. The Influence of the main pretreatment variables including temperature,...

8-Stearolactone was prepared from oleic acid using concentrated sulfuric acid under various conditions in the presence of polar, nonparticipating solvents. 8-Stearolactone was formed in as high as 15:1 ratios over the thermodynamic product, y-Iactone, in the presence of methylene chloride, 100% wt/vol, at room temperature with two equivalents of sulfuric acid for 24 h. This procedure is applica...

the characterizations of natural diatomite from birjand deposit (iran) were studied such as chemical compositions, specific surface area, total pore volume, pore size distribution and xrd. the diatomite that was treated only with sulfuric acid displayed a larger surface area, expanded total pore volume and increased pore size in comparison with both washed natural diatomite with deionized water...

A direct procedure for the determination of total polysaccharides (TPS) in Camellia sinensis was set up based on the modified phenol-sulfuric acid method. The monosaccharide composition of TPS was analyzed by GC. Based on the results of GC, model monosaccharide mixtures were made which provided an adequate standard for this procedure. Through single-factor and orthogonal (L93) experiments, the ...

Particles in the upper troposphere and lower stratosphere (UT/LS) consist mostly of concentrated sulfuric acid (40-80 wt %) in water. However, airborne measurements have shown that these particles also contain a significant fraction of organic compounds of unknown chemical composition. Acid-catalyzed reactions of carbonyl species are believed to be responsible for significant transfer of gas ph...