Total carbohydrates, determination

Derenbach (1970) made a distinction between soluble and combined RNA of planktonic material from the different behaviour of these compounds after different extraction procedures. He and others (see Derenbach, 1970 for references), employed the orcinol/hydrochloric acid reagent according to Ceriotti (1955). Since a variety of other sugars may interfere (see section 3.1 orcinol/sulphuric acid has also been used as a reagent for total carbohydrate determinations) correction factors or preferably chromatographic separations of the extracts are required for quantitative results. 

Jorgensen, N. O. G., and R. E. Jensen. 1994. Microbial fluxes of free monosaccharides and total carbohydrates in freshwater determined by PAD-HPLC. FEMS Microbiology Ecology 14 79-94. 

The quantification of specific sugars and total carbohydrates should be performed in each lot. In some cases, IEF and capillary electrophoresis can be alternative methods for determining the percentage of each isoform in a product sample lot. It is often important to determine the isoform profile for each lot prior to release. It would be ideal, but not always possible, to relate the isoform profile to the specific activity of the product. 

One of the most common hydrolysis reactions is that required to convert polysaccharides into monosaccharides prior to the determination of total carbohydrates in food and environmental samples. The use of highly acid media (e.g. 12 M sulphuric acid) and elevated temperatures ( 100°C) for 20 min produced partial oxidation of carbohydrates [80]. Using room temperature to avoid oxidation resulted in incomplete hydrolysis [81], and so did lowering the concentration of sulphuric acid to 0.5 M while keeping the temperature at 100°C for 8 h [82-84]. One of the most accurate ways of determining total carbohydrates is by using 1 M HCI at 100°C for 20 h [85,86]. 

Other workers determined the entire carbohydrate spectrum of human gastric juice in an attempt to evaluate the composition of gastric mucosubstances. Richmond et al. (R4) and Hoskins and Zamcheck (H50) studied a large number of individual gastric juices in our laboratory (G55) a large pool of normal gastric juices was studied for hexoses, hexosamine, fucose, sialic acid, uronic acid, and total carbohydrate content. Results obtained in normals and patients with various gastric diseases are summarized in Tables 8 and 9. 

The total carbohydrates of various soils have been determined, after hydrolysis, by measuring the reducing substances by the Bertrand and Hagedorn-Jensen methods. Soil hydrolyzates always contain humic substances which reduce Fehling solution they do not, however,... 

The quantitative determinations, although not always satisfactory, have shown the carbohydrates to constitute about 10% of soil organic matter. The major immediate problem is development of better methods for the determination of the total carbohydrates and their individual monosac-... 

Holocellulose is the total carbohydrate content of wood. The values here are 100 — (the sum of percent ash, EtOH/benzene solubles, hot-water solubles, and lignin). Values from Refs. 73 and 76 were experimentally determined. 

Adsorption can be used to differentiate between free dissolved monomeric phenols and monomeric carbohydrates. Muenster (1982) showed that the sum of both monomeric substance classes in Lake Plussee water comprised between 3 and 10% of the total DOC concentration depending on the resin used. Perdue and co-workers (Lytle and Perdue, 1981 Sweet and Perdue, 1982) utilized Amerlite XAD-7 resin to adsorb humic substances and determined free dissolved amino acids and humic-acid-associated amino acids, as well as monosaccharides, polysaccharides, and humic-bound saccharides in the Williamson river system (Oregon). As a mean, less than 4% of the dissolved amino acids occurred in free dissolved form, and only 2.6% of the total carbohydrates were monosaccharides. This observation as well as some ecophysiological implications are described more extensively in a later section. 

Carbohydrates. Carbohydrate (neutral sugar) content and relative distribution were determined by gas chromatography for humic substances from Lake Haruna sediments (Uzaki and Ishiwatari, 1983 Uzaki, unpublished). The results indicated that the concentration of total carbohydrates in fulvic acid (16.8% of fulvic acid) was higher than those in the other humic fractions (2.4-4.0%). C lrbohydrate distribution in three humic fractions resembled... 

Prothrombin is the precursor of the serine protease thrombin, essential for normal haemostasis in activation of platelets and in catalysing the polymerisation of fibrinogen to fibrin. It is synthesized in the liver and contains about 8% total carbohydrate in four N-glycans. Three of these lie on the Pro region and only one is present on the mature a-thrombin molecule. The structure of the thrombin glycan has been determined by mass spectrometry and is the same as that shown in Fig. 5 A with fucose absent or present [77]. 

Prodolliet J., Bruelhart M., Lador F., Martinez C. et al. (1995a) Determination of free and total carbohydrate profile in soluble coffee. J. Ass. Off. Anal. Chem. 78(3), 749-61. 

Protein content in the yeast biomass was also determined by the Kjeldahl method using the conversion factor of 6.25. Total carbohydrates in yeast biomass were determined by the anthrone method [21]. RNA content was determined by the Schmidt-Thannhauser method as described in Benthin et al. [22]. Fat content was determined in dried cells by a Soxhlet extraction procedure using petroleum ether (60-80 °C) as solvent [23]. Ash content was determined by igniting the samples at 575 °C for 5 h, both for the feedstock and yeast biomass. All results are reported on the dry basis. 

Despite the great interest in this class of compound and the numerous reports concerning the determination of total carbohydrates in seawater, surprisingly few determinations of individual monosaccharides have been made. Unlike the determination of free amino acids in seawater, no method for direct determination of free monosaccharides exists at present. Analogous to the developments in the detection of DFAA, the introduction of direct analysis techniques may change our concepts of the pattern of free sugars in seawater at a future date. 

A number of methods are available for the determination of total carbohydrates in detritus and soil organic matter. For an additional discussion on characterization and associated methodologies, see Stevenson (1994). 

Chemical analyses. Total carbohydrate was determined by the phenol-sulfuric acid method of Dubois (1 ), and total... 

Analysis of sugar composition in nectar can be used for detecting variation between flowers or nectaries from different taxonomic varieties, and consequently generate differences in type and frequency of visitation of pollinators. Alves et al. (2010) studied the total sugar concentration in soybean nectar Glycine max L. Merrill) var. Codetec 207 by spectrophotometry, using the general method for carbohydrates determination by phenol-sulphuric technique (Dubois et al., 1956). 

The total carbohydrate content of rat liver has been determined in a single-step procedure using glucoamylase and D-glucose oxidase. This is a modification of an earlier two-step system for the measurement of rat-liver glycogen. 

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