Sugars analysis

Sugar amides Sugar analyses Sugar analysis... 

Basic Lead Acetate. Basic lead acetate [1335-32-6] (lead subacetate), 2Pb(0H)2-Pb(C2H3 02 )2, is a heavy white powder which is used for sugar analyses. Some physical properties are given in Table 4. Reagent grade is available in 11.3-kg cartons and in 45- and 147-kg fiber dmms. 

The difficulties inherent in obtaining correct sugar analyses for a polysaccharide containing three different amino sugars are obvious. It therefore seems possible that S4 is composed of tetrasaccharide repeating-units, containing one residue each of the four different sugar components. 

Sowden et al. [4] also did detailed amino acid and amino sugar analyses of the soils from the different dimatic regions. The following amino acids were determined acidic amino acids aspartic and glutamic acids basic amino acids arginine, histidine, lysine and ornithine neutral amino adds, phenylalanine, tyrosine, glycine, alanine, valine, leudne, isoleudne, serine, threonine, proline and hydroxyproline ... 

Sugar analyses -lead compounds for [LEAD COMPOUNDS - LEAD SALTS] (Vol 15)... 

An old-fashioned chemist would perform sugar analyses by Fehlings titration before and after inversion and polarimetry. A technique very... 

Fig. 9. Schematic diagram of colorimetric sugar analyser. PI and P2 are medium pressure pumps BT = bubble trap PD = pulse dampeners and BP = back pressure coil to suppress boiling.

Fig. 10. A. Chromatogram of a standard mixture of sugars analysed under conditions (b) Table III. Five nanomole of each sugar injected. Peak identity 2-d-GAL = 2-deoxygalac-tose 2-d-RIB = 2-deoxyribose CELL = cellobiose RHAM = rhamnose MAL = maltose LAC = lactose R/B = ribose AfAAf = mannose FRt/C = fructose ARA = arabinose FCC = fucose GAL = galactose XFL = xylose MAN-//RR = mannoheptulose GLU-HEP = glucoheptose GLU = glucose.

Several laboratories routinely use alditol acetate derivatives for analyzing sugar mixtures by g.l.c. in combination with m.s. The usefulness of the method is illustrated by the following examples. Sugar analyses of lipopolysaccharides from Salmonella species have demonstrated that several chemotypes contain 3,6-dideoxyhexoses. When these sugars are converted into alditol acetates, the isomers can be separated by g.l.c., and their identity as 3,6-dideoxyhexoses can be established by... 

Some polysaccharides contain naturally methylated sugars. Analyses of the lipopolysaccharides from Myxococcus fulvus and Rhodopseudo-... 

The results of sugar analyses of the CWM and AIR (Table VI) from parallel batches of apples likewise indicate similar overall carbohydrate compositions with only small losses of pectlc substances from the CWM, a conclusion again supported by the isolation of smaller quantities of these materials on subsequent extraction. Structural studies on apple polysaccharides will be reported elsewhere. 

Sugar Analyses. Hydrolyses of polysaccharide fractions and cell trail preparations were performed (a) directly with trlfluoroacetic acid ( ) and (b) after digestion with 72% sulfuric acid and dilution, with M-sulfuric acid (O. Allose was added as an Internal standard and the sugar mixtures were converted Into alditol acetates (12) for analysis by glc on column (a). Uronlc acid determlnaclons were carried out spectrophotometrlcally with the 3-hydro3qrdlphenyl reagent ( ). In the case of Insoluble materials determinations were performed after digestion with 72% sulfuric acid and appropriate dilution. 

Enzymatic hydrolysis of pretreated cellulose from both the batch and flowthrough systems was conducted at a 2% solids concentration (g dry weight/100 mL) in 50 mM acetate buffer (pH 4.8) containing 40 pg/mL tetracycline and 30 pg/mL cycloheximide. Flasks were pre-incubated at 50°C in water using an orbital shaker bath (3540, Bamstead International, Dubuque, lA) at 150 rpm for 10 minutes, and the enzymes were added to start the hydrolysis after acclimation. Aliquots of 0.5 mL were taken at different times (0,4,24,48, 72 h), immediately chilled on ice, and centrifuged at 5000 G for 10 min. Total sugar analyses were carried out on the resultant supernatants. 

The retention behavior of fructose, glucose, sucrose, maltose, and lactose on various aminopropyl columns (RI detector) was studied using an 80/20 acetonitrile/water mobile phase. Elution for all compounds was complete in 15-20 min with all peaks well resolved. This method, or one very similar to it, is used for the sugar analyses of a wide variety of food products. For example, a food sample that contains elevated salt levels poses a problem for sugar analyses since the chloride ion can coelute with fructose under normal conditions [1204]. In this work, the optimal mobile phase composition of 70/30 acetonitrile/water (on an aminopropyl colunm) had to be modified to 75/25 in order to shift the retention of the first-eluting sugar (fructose) past the elution time of chloride (here 4 min or Ji/ 1). Standards of n oWn w/w were made and 25 uL was injected. 

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