Determination of carbohydrates in plants

Summary A suitable paper-chromatographic method for the serial determination of carbohydrates in plants is described. For the analysis of these substances conditioned both fresh and freeze-dried or better air-dried samples of plant material can be used. However in contrast to the meaning of many authors it is not recommendable to use fresh or freeze dried plant samples, because more than half of the sucrose fraction is splitted into glucose and fructose. A discussion of the difficulties involved in the preparation and conservation of the plant matter as well as in the determination of carbohydrates is left out of account. In this respect, reference is made to the literature indicated.

---

Bestimmung von Kohlenhydraten in Pflanzen

Zusammenfassung Zur Kohlenhydratbestimmung in Pflanzen wird ein für Serienbestimmungen geeignetes papier-chromatographisches Verfahren beschrieben. Im Gegensatz zu anderen Autoren werden luftgetrocknete Proben empfohlen, da bei frischen oder gefriergetrockneten Pflanzen über die Hälfte der Saccharose in Glucose und Fructose gespalten ist. Die Methodik wird eingehend beschrieben, bezüglich der Schwierigkeiten und Probleme der Probenvorbereitung und der Analyse wird auf andere Veröffentlichungen verwiesen.

     

Determination of neutral carbohydrates by CZE with direct UV detection

A new CZE method relying on in-capillary reaction and direct UV detection at the wavelength 270 nm is presented for the simultaneous separation of the neutral carbohydrates xylitol, D-(-)-mannitol, sucrose, D-(+)-fucose, D-(+)-cellobiose, D-(+)-galactose, D-(+)-glucose, L-rhamnose, D-(+)-mannose, D-(-)-arabinose, D-(+)-xylose, and D-(-)-ribose. The alkaline electrolyte solution was prepared of 130 mM sodium hydroxide and 36 mM disodium hydrogen phosphate dihydrate. Separation of the sample mixture was achieved within 35 min. Calibration plots were linear in the range of 0.05-3 mM. Reproducibility of migration times was between 0.3 and 1.1%, and the detection limits for the analytes were 0.02 and 0.05 mM. The optimized method was applied for the determination of neutral monosaccharides in lemon, pineapple, and orange juices and a cognac sample. The methodology is fast since no other sample preparation except dilution is required.     

Determination of carbohydrates by condensation with 3-methyl-2-benzothiazolinonehydrazone

The condensation reactions obtained by heating carbohydrates with 3-methyl-2-benzothiazolinonehydrazone (MBTH) in alkaline solution containing 2-methoxyethanol are utilized. The absorbance of the product is measured at 390 nm against the reagent blank. D-Glucose (50–350 nmol) can be determined accurately with coefficients of variation less than 1.5%. Other reducing carbohydrates give similar results. The selectivity of this method is discussed.     

Determination of post-culture processing with carbohydrates by MALDI-MS and TMS derivatization GC-MS

Biological materials generally require stabilization to retain activity or viability in a dry form. A number of industrial products, such as vaccines, probiotics and biopesticides have been produced as dry preparations. The same methods and materials used for stabilizing commercial microbial products may be applicable to preserving biothreat pathogens in a dry form. This is a likely step that may be encountered when looking at samples from terrorism attempts since only spores, such as those from Bacillus anthracis, are inherently stable when dried. The stabilizers for microbial preparations generally include one or more small carbohydrates. Different formulations have been reported for different industrial products and are often determined empirically. However sugar alcohols (mannitol and sorbitol) and disaccharides (lactose, sucrose and trehalose) are the common constituents of these formulations. We have developed an analytical method for sample preparation and detection of these simple carbohydrates using two complementary analytical tools, MALDI-MS and GC-MS. The native carbohydrates and other constituents of the formulation are detected by MALDI-MS as a screening tool. A longer and more detailed analysis is then used to specifically identify the carbohydrates by derivatization and GC-MS detection. Both techniques were tested against ten different types of stabilization recipes with Yersinia pestis cell mass cultured on different media types used as the biological component. A number of additional components were included in these formulations including proteins and peptides from serum or milk, polymers (e.g. poly vinyl pyrrolidone - PVP) and detergents (e.g. Tween). The combined method was characterized to determine several figures of merit. The accuracy of the method was 98% for MALDI-MS and 100% for GC-MS. The repeatability for detection of carbohydrates by MALDI-MS was determined to be 96%. The repeatability of compound identification by GC-MS was determined by monitoring variation in retention time, which is vital for identification of isomeric carbohydrates. The figures of merit illustrate an effective and accurate method for mono and disaccharide detection independent of formulation. This meets our primary goal for method development as small carbohydrates are among the most common stabilizers employed.     

Kinetics of Ca2+ complexation with some carbohydrates in aqueous solutions

For solutions of four saccharides in water with alkaline-earth chlorides added ultrasonic attenuation spectra between 100 kHz and 2 GHz are reported and compared to those for carbohydrate solutions without salt. Calcium chloride does not alter the relaxation times in the spectra of D-glucose and D+-maltose solutions, reflecting the exocyclic hydroxymethyl group rotation, a saccharide-saccharide association, and, with the disaccharide, also motions of both rings of a molecule relative to one another. The spectra of D-xylose and D-fructose solutions are substantially changed by the salts. With both saccharides an additional term with relaxation time around some nanoseconds exists which is assigned to a rearrangement of a carbohydrate-cation complex. Other relaxation terms of these saccharide solutions are also subject to noticeable changes by the salt, indicating specific carbohydrate-cation interactions. The ultrasonic spectra show that such interactions may exist also with carbohydrates which do not display the particular hydroxyl group sequences that are considered to promote complexation with cations.     

Determination of carbohydrates by direct injection enthalpimetry

An analytical method for the determination of carbohydrates is described, which is based on the enthalpimetric signal obtained at the beginning of the reaction with periodate. The apparatus is described and relevant aspects of the procedure are discussed. Single carbohydrates can be determined in a few minutes with a precision of 1%. Analysis of mixtures of glucose and fructose is reported.     

Determination of carbohydrates by capillary electrophoresis with electrospray-mass spectrometric detection.

A method for the determination of underivatized carbohydrates using capillary electrophoresis (CE) with detection by electrospray ionization-mass spectrometry (ESI-MS) presented. Highly alkaline carrier electrolytes based on volatile organic bases like is diethylamine (DEA) combined with MS detection in the negativ-ion mode proved to be the optimum solution for the separation and detection of these analytes. Optimization of the carrier electrolyte composition has been performed with respect to its pH, ionic strength as well as the addition of an organic modifier. The influence of the DEA concentration in the sheath liquid on parameters like peak shapes or signal-to-noise (S/N) ratios was also investigated. Limits of detection (LOD) were in the range of 0.5-3.0 mgL(-1) and calibration was linear over an order of magnitude for almost all solutes investigated. Finally, the applicability of this method for the analysis of real samples was demonstrated with wine samples.     

Micellar catalysis of oxidation of glycolic acid by N-bromophthalimide

Catalysis of oxidation of glycolic acid by N-bromophthalimide by micelles of cetyltrimethylammonium bromide (CTAB) at 318 K was investigated. The observed value of critical micelle concentration of CTAB in the presence of other components was lower than those reported in the literature. The oxidation reaction was strongly catalyzed by cationic micelles of CTAB. The reaction rate increased with CTAB concentration until the steady state was achieved. The reaction kinetics corresponded to first, fractional and inverse fiactional orders with respect to changes of concentration of reaction components. Effects of solvent, phthalimide, mercuric acetate, and potassium chloride on the reaction kinetics were also studied. The micelle-catalyzed oxidation reaction was shown to fit Arrhenius equation. The experimental data were rationalized in terms of Menger-Portnoy model considering a distribution of the reactants between the micellar and aqueous phases.     

Determination of some sulphur compounds with N-bromoimides

Two stable oxidants, N-bromophthalimide and N-bromosaccharin are proposed as reagents for the visual and potentiometric titrimetric of thioureas, isothiocyanates, xanthates, dithiocarbamates, thiols, sulphur, thiosulphate, thiocyanate and thiocarbonate. The results are precise within 0.1-0.3%.     

Density functional theory study of the FT-IR spectra of phthalimide and N-bromophthalimide

Fourier transform infrared (FT-IR) spectra of phthalimide and N-bromophthalimide have been recorded in the range of 4000-400 cm-1. With the hope of providing more and effective information on the fundamental vibrations, a normal coordinate analysis has been performed on phthalimide and N-bromophthalimide, by assuming C2v symmetry. Density functional theory (DFT)-Beck3-Lee-Yang-Parr (B3LYP) levels with 6-31G* and 6-311+G** basis sets have been employed in quantum chemical analysis. The computational frequencies are in good agreement with the observed results. The theoretical spectra obtained along with intensity data agree well with the observed spectra.     

Investigation of the carbohydrates of some plant species of central Asia

Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 622–623, July–August, 1995. Original article submitted October 24, 1994.     

Kinetics and mechanism of oxidation of aspirin by bromamine-T,N-bromosuccinimide,and N-bromophthalimide

The kinetics of the oxidation of aspirin (ASP) by bromamine-T (BAT), N-bromosuccinimide (NBS), and N-bromophthalimide (NBP) has been studied in aqueous perchloric acid at 303 K. The oxidation reaction follows identical kinetics with first-order in [oxidant], fractional-order in [ASP], and inverse fractional-order in [H⁺]. Under identical experimental conditions the extent of oxidation with different oxidizing agents is in the order: NBS>BAT>NBP. The rate decreased with decreasing dielectric constant of the medium. The variation of ionic strength and the addition of the reaction products and halide ions had no significant effect on the reaction rate. The solvent isotope effect was studied using D₂O. Kinetic parameters were evaluated by studying the reaction at different temperatures. The reaction products were identified by GC–MS. The proposed reaction mechanism and the derived rate law are consistent with the observed kinetic data. Formation and decomposition constants for ASP-oxidant complexes have been evaluated. Decarboxylation, bromination, and loss of acetic acid gave 2,4,6-tribromophenol. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet: 30: 407–414, 1998     

Determination of "net carbohydrates" using high-performance anion exchange chromatography

For labeling purposes, the carbohydrate content of foods has traditionally been determined by difference. This value includes sugars, starches, fiber, dextrins, sugar alcohols, polydextrose, and various other organic compounds. In some cases, the current method may lack sufficient specificity, precision, and accuracy. These are subsequently quantitated by high performance anion exchange chromatography with pulsed amperometric detection and expressed as total nonfiber saccharides or percent "net carbohydrates." In this research, a new method was developed to address this need. The method consists of enzyme digestions to convert starches, dextrins, sugars, and polysaccharides to their respective monosaccharide components. These are subsequently quantified by high-performance anion exchange chromatography with pulsed amperometric detector and expressed as total nonfiber saccharides or percent "net carbohydrates." Hydrolyzed end products of various novel fibers and similar carbohydrates have been evaluated to ensure that they do not register as false positives in the new test method. The data generated using the "net carbohydrate" method were, in many cases, significantly different than the values produced using the traditional methodology. The recoveries obtained in a fortified drink matrix ranged from 94.9 to 105%. The coefficient of variation was 3.3%.     

Determination of some trace elements in some human concretions

The contents of Hg, Cr, La, Sc, Co, Fe and Sb in some human concretions have been determined by instrumental radioactivation analysis. Urinary bladder and kidney concretions surgical removed from the patient have also been analyzed.