Isolation and spectroscopic study of pectic substances from kenaf (Hibiscus cannabinus L.)

Pectins were isolated from bark, wood and pith of kenaf (Hibiscus cannabinus L.) variety Cuba108. Imidazole was used as extractant. The isolated pectins were studied by 13C nuclear magnetic resonance (13C-NMR) spectroscopy and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). From the spectroscopic investigation, the isolated pectic substances were found similar to commercial pectins.     

Spectroscopic determination of the degree of atomization in an electrothermal atomizer

The degree of atomization, β, is measured for an electrothermal atomizer by comparing the emission lines of copper atoms and CuCl molecules. Hydrogen increases the β value. The determined β value of CuCl is used as a standard for the determination of β values of other elements (nickel, chromium, tin and lead).     

Enzymatic hydrolysis of pectic substances by gel-permeation chromatography

Summary A rapid liquid chromatographic (HPLC) method for the determination of pectinolytic activity of enzymes produced by Aspergillus Niger and Rhizopus species is reported.Compared with more conventional methods, HPLC is more reliable and has a much improved maximum sensitivity. The limit of quantitation of galacturonic acid is 0.1g.     

Purification of total phospho- and phosphonolipids of cotton and kenaf seeds from accompanying substances

The quantitative amounts of the essential oil of the European white birch of the Yakut population in the annual cycle and its component composition have been investigated.V. N. Sukachev Forest and Timber Institute, Siberian Branch, USSR Academy of Sciences, Krasnoyarsk. Novosibirsk Institute of Organic Chemistry, Siberian Branch, USSR Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 803–805, 1987.     

Phosphono analogue of phosphatidylethanolamines from kenaf seeds

Institute of the Chemistry of Plant Substances, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, Vol. 6, pp. 848–849, November–December, 1989.     

Spectroscopic approaches to the study of the interaction of aluminum with humic substances

Aluminum ion (Al³⁺) in the ‘free’ (aquo) state is becoming increasingly prevalent in environmental waters, especially fresh waters, as a consequence of acid rain and other environmental processes. As Al³⁺ ion is known to affect markedly a wide range of biological systems, and since the presence of Al³⁺ in humans has been linked to a number of human diseases, it is important to understand the speciation of Al³⁺ ion in natural waters. Since some of the most important complexation agents for Al³⁺ in both fresh and sea waters are members of the complex humic substances group, it is important to understand the manner in which Al³⁺ interacts with this class of molecules, especially since binding of Al³⁺ to these molecules can effectively increase the bioavailability of this toxic metal ion to biological systems. The objective of this review is to present the current state of our understanding of aqueous aluminum complexation with the most acidic members (and therefore the most likely candidates for serving as Al³⁺ complexing agents) of the humic substances group, the fulvic acids. Much of the current knowledge has been revealed by comprehensive fluorescence titration analyses. Some additional information has come from other experimental approaches, including infrared spectroscopy, nuclear magnetic resonance spectroscopy, and a variety of electrochemical approaches. In this review, we also report on the results of our recent fluorescence and IR spectroscopy survey of the interaction of metals from of all three Nieboer and Richardson categories of environmental metals (Class A, Class B and Intermediate Class) with the fulvic acid sub-group of the humic substances. This has proven helpful in understanding some of the unique spectral behaviors of the Al³⁺-fulvic acid complex vis-a-vis fulvic acid complexes with many other metal ions. The results of our fluorescence and IR experiments with the model compounds, such as salicylic and phthalic acids, have allowed confirmation of the important roles played by both salicylic acid-like sites and phthalic acid-like sites in the unique complexation of Al³⁺ to humic substances, and help to explain some of the observed spectroscopic changes associated with Al³⁺ ion complexation to humic material. From the current work, it seems clear that major sources of the deviation in spectral properties between Al³⁺ and many other metal ions (across all three Nieboer and Richardson categories) are the unusually high value of its charge density and relatively low propensity for involvement in covalent bonding interactions (i.e. a very high ionic index combined with a relatively low covalent index in the Nieboer and Richardson classification of environmental metals), as well as affinity for certain functional groups.     

Spectroscopic method for the determination of crystallinity of hematite

The thermal transformation of goethite to hematite and the temperature dependence of the degree of crystallinity have been investigated using transmission and diffraction electron microscopy and infrared spectroscopy. The electron microscopy results reveal that the treatment of natural goethite by NaOH or citrate dithionite-bicarbonate (CDB) has no effect on its structure but leads to increase in the crystallinity of the ore. On the other hand, heat treatment of the untreated or treated sample is found to convert goethite ore to hematite with increase in its crystallinity. An infrared spectroscopic technique is applied for quantitative calculation of the crystallinity changes.     

The determination of kinetic parameters for the decomposition of complex substances from thermogravimetry data

A procedure for thermogravimetry data processing was suggested. It was based on treatment of a substance as a superposition of fractions, the decomposition of which occurred independently and could be described by first-order kinetics with the corresponding kinetic parameters, that is, activation energy and preexponential factor. The theoretical dependences of weight loss were constructed using exact solutions to kinetic equations. The results obtained by the determination of the kinetic parameters for two coal samples are presented.     

FT-IR Determination of degree of esterification in polycarboxylic acid cross-link finishing of cotton

Cross-linking of cotton with polycarboxylic acids, applied with catalysts based on phosphorus-containing inorganic acids, produces fabrics with excellent smooth-drying properties and which release no formaldehyde at any stage of preparation or on storage. The reaction produces cellulose ester linkages and unreacted carboxylic acid groups. Fourier transform infrared spectroscopy was used to determine the degree of esterification of polycarboxylic acids that occurred on cross-linking of cotton. The height of the carbonyl peak at 1730 cm ^–1 was determined on the same treated fabrics after soaking in dilute acid to convert ionized groups to free acid and then in dilute base to convert free acid to carboxylate ion. The carbonyl peak for the base rinsed fabric (ester only) was ratioed against the same peak for the acid-rinsed fabric (total carbonyl, ester plus acid) to obtain a measure of the degree of esterification. This ratio minimizes the problems of different molar extinction coefficients that are encountered when peaks from different functional groups are used.     

Gasometric determination of nitrogen in organic substances

Summary A modification of the Dumas-Pregle micromethod has been developed, permitting the determination of nitrogen in simple and difficultly liquefied organic compounds, thanks to me use of preliminary pyrolysis for decomposing the sample. The accuracy of the method is 0.1–0.2%. Duration of the determination is 20–25 min.The work was begun under the supervision of M. O. Korshun.