Electrochemical methods for the determination of ascorbic acid in biologically active additives
A.I. Fokina, E.G. Fominykh, K.I. Yuzhanin
Section: Methodology and research methods. Models and forecasts
One of the negative consequences of the impact of adverse environmental factors on on a humans is the development of oxidative stress in the body, which causes deviations in the state of human health. An important role in the fight against oxidative processes is played by antioxidants, including ascorbic acid (AA). Along with food, biologically active additives (BAA) can be an additional source of AA intake into the body.
The correct assessment of the АА content in pharmaceutical preparations helps to solve an important problem of food ecology – the balanced use of vitamin C. Therefore, the development of new and improvement of existing methods of analysis for determining the content of AA in various objects remains an urgent task.
The use of instrumental methods for fixing the end point of the titration increases the accuracy of the analysis. Simple and economical electrochemical methods such as potentiometry and coulometry can be used to implement the iodometric titration method. Despite all the advantages of coulometric and potentiometric methods of analysis and their
widest distribution in various fields of science and technology, there are no data in the literature on the possibility of
implementing the coulometric determination of АА with potentiometric indication and direct potentiometric titration, which are based on the reaction with iodine.
As a result of the study, it was found that in the determination of AA by both methods, well-repeated results were obtained (the relative standard deviation does not exceed 2.0%), the dependence of the analytical signal on the sample
mass (in the range of 80–120% to standard weight 0,1 or 0,2 g depending on the method) is linear with R not less than 0.99, and the results obtained by the “introduced-found’’ method satisfy the requirement of correctness.
Heavy metals (HM) in the soil cause changes in the ratio of resistant and susceptible fungal species, the mechanisms of interaction between which are not well understood. The aim of this work is to study the resistance to Cu and Pb cations and the antagonistic properties of two species of soil micromycetes Alternaria alternata and Trichoderma viride. Fungal resistance was assessed by the following test functions: biomass accumulation, colony diameter, and sporulation activity. The antagonistic activity of fungal species was assessed by competition test. The calculated effective concentrations and tolerance indices made it possible to conclude that A. alternata and T. viride are highly resistant to the investigated HMs. At the same time, species differences in the patterns of reactions were found. The growth of A. alternata colonies was inhibited to a greater extent than T. viride, however at the same HM concentration, the stimulation of sporulation in Alternaria was more pronounced than in the rapidly growing Trichoderma. The studied strain T. viride turned out to be quite competitive with respect to the phytopathogenic fungus A. alternata, and its antagonistic properties were well pronounced in the medium with HM. The data obtained can be useful for predicting the phytopathogenic activity of micromycetes against the background of chemical pollution and the dynamics of accumulation of various fungal species under adverse environmental conditions.
Large industrial pig farms are a source of biological contamination of arable lands located in the immediate vicinity of these enterprises, as a result of the introduction of large volumes of liquid fraction of manure effluents. Utilization of these biogenic wastes is a serious economic and environmental problem for the agro-industrial complex. The work is devoted to the study of the influence of the liquid fraction of pig farm manure effluents on the sanitary condition of arable land according to agrochemical and microbiological studies of soil samples. The study revealed that the regular introduction of pig manure into arable land (for 5 years) led to a significant increase in the content of mobile forms of phosphorus and potassium; there was a pronounced tendency to the accumulation of copper and zinc in the arable horizon of the soil, in addition, high values of the total microbial number, the index of bacteria of the group Escherichia coli, Enterococci and Clostridium perfringens. Salmonella, including pathogenic and thermophilic bacteria, were found in significant quantities. In addition, pig manure effluents are potential sources of ingress into the soil of agricultural land, as well as adjacent territories with saprophytic microorganisms, as well as bacteria of the group E. coli, C. perfringens, Proteus spp., Clostridium spp., Salmonella enteritidis, fungi Alternaria alternate, Botrytia cinerea, yeast Saccharomyces cerevisiae. Insufficient attention to environmental monitoring of territories adjacent to livestock enterprises can lead to chemical and biological pollution of the environment by a wide range of pollutants present in manure runoff, and the intensification of the development of the industrial pig industry will accelerate this process.
Section: Methodology and research methods. Models and forecasts
The article presents a comparative evaluation of the prospects for using sulfur-conducting solid electrolytes CaY2S4 and CaYb2S4 doped with ytterbium sesquisulfide (Yb2S3 ) as part of solid electrolyte sensors of sulfur-containing gases (hydrogen sulfide and sulfur dioxide). The relationship between the magnitude of the sensor signal and the electrode reactions at the working electrode is considered, taking into account the partial pressures over its components, and the nature of the signals during the detection of H2S and SO 2 is substantiated. The intervals of gas concentrations that fall into the group of linear signs depending on the content of the detected gas are determined. It has been suggested that the reason for the low sensitivity of the sensors in the range of PS < 10-10 atm is a kinetic nature. As a result of the study, it was found that when detecting a gas containing hydrogen sulfide, the limiting stage is the reaction of adsorption of hydrogen sulfide on the surface of the working electrode (reaction of the first order), and when determining the content of sulfur dioxide, the limiting rate reaction is the desorption reaction of a by-product – oxygen (reaction of the second order). It was carried out a kinetic study of the relationship between the sensitivity of hydrogen sulfide and sulfur dioxide sensors and outlined the sensitivity path of performance sensors. It was found that for the detection of hydrogen sulfide and sulfur dioxide, it is more promising to use the sulfur-conducting solid electrolyte CaY2S4 – x mol.% Yb2S3, where х is 0 to 16 mol.%, the sensor sensitivity is an order of magnitude higher than the use of solid electrolyte CaYb2S4 – x mol.% Yb2S3, where х is 0 to 12 mol.%.
Section: Monitoring of natural and anthropogenically disturbed areas
The importance of the “Koigorodskiy” National Park (Komi Republic) for conservation of protected plants and fungi key habitats is demonstrated for the first time. By now, we registered here 367 occurrences of 32 rare species of plants and fungi, included in the Red Data Book of the Komi Republic. Among them, 11 taxons of plants (7 species of vascular plants and 4 species of bryophytes), and 21 taxons of fungi (9 species of fungi, 11 species of lichens and 1 species of lichenicolous fungi) were found. Three species of vascular plants and nine taxons of lichens require monitoring of their nature populations and are included in the Appendix 1 to the Red Data Book of the Komi Republic. Our results confirm the priority of the Koigorodskiy National Park for conservation of biological diversity
Section: Methodology and research methods. Models and forecasts
Polylactide is one of the most environmentally friendly polymers to replace fossil-based materials. In this work we
quantitatively evaluated the effectiveness of new photostabilizers in preventing the photodegradation of polylactide under UVC radiation by using the spectrometric criteria calculated from FTIR spectra. We have proposed a method including a treatment of the samples of polylactide mixed with the photostabilizers by the UV radiation with a wavelength of 254 nm for 4 hours followed by the calculation of the effectiveness of the photostabilizer based on the FTIR spectrometric data. The number of terminal hydroxyl groups increased during photodegradation due to the cleavage of ester bonds in the polymer, this caused the increase of the absorption at 3600–3100 cm -1 in the FTIR spectra. Several photostabilizers of the terpenophenol class were studied, namely 4-methyl-2,6-diisobornylphenol, 2-isobornylphenol, 2-isobornyl-4-methylphenol
and 2-isobornyl-6-methylphenol, as well as bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate – the well-known hindered
amine light stabilizer. The mass concentrations of these photostabilizers varied from 0.05 to 1.00%.
The best protection effect from the UVC radiation in regard to polylactide was shown by 4-methyl-2,6-diisobornylphenol at the concentration of 0.05% by weight. Its photoprotective activity was almost 2 times higher
than that of bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate of the same concentration. The high photoprotecting
activity of 4-methyl-2,6-diisobornylphenol was due to the increased stability of the phenoxy radical provided by
bulky isobornyl substituents in the aromatic ring. In the opposite, the strong photosensitizing effect accelerating the photodegradation of polylactide was manifested by 1% concentrations of 2-isobornyl-4-methylphenol and
2-isobornyl-6-methylphenol. In this case, the delocalization of the unpaired electron in the conjugation chain with the formation of many resonance forms contributed to the transfer of the radical to polylactide macromolecules. The protection of polylactide from UVC radiation opens up prospects for expanding the areas of application of polylactide, a polymer synthesized from renewable raw materials.
Keywords: renewable raw materials, polylactide, photoprotectors, infrared spectrometry
Article published in number 3 for 2022 DOI: 10.25750/1995-4301-2022-3-026-033
Ecological and demographic characteristics of Cypripedium calceolus L. coenopopulations in the Kirov region
N.Y. Egorova, V.N. Suleymanova, E.V. Ryabova
Section: Population ecology
The results of studying the ecological and demographic parameters of 10 cenopopulations (CP) of Cypripedium calceolus L. in the subzone of the southern taiga in the Kirov region (Slobodskoy, Afanasievsky, Lebyazhsky districts) are presented. In habitats with C. calceolus, the main background of plant groupings is formed by representatives of boreal and non-morale ecological-cenotic groups. The limiting factors affecting the spread of the species are the illumination and acidity of the soil. The generative-oriented type of the ontogenetic spectrum is predominant. According to the “delta–omega” classification, the studied CPs are represented by aging and transitional types. According to the vital state, most CPs are thriving, with the exception of CP 5, 7. A comprehensive assessment of the state of C. calceolus showed that the populations are in a state “close to threatened” or “dependent on conservation”.
Article published in number 3 for 2022 DOI: 10.25750/1995-4301-2022-3-166-174
Сhemical land degradation under the influence of animal husbandry waste
N.V. Syrchina, L.V. Pilip, T.Ya. Ashikhmina
Systematic introduction of significant volumes of liquid fraction (LF) of manure effluents into arable land leads to a significant transformation of the physical and chemical properties of agrozems. Under the influence of LF, the content of mobile forms of phosphorus (up to 980–1170 mg/kg), exchangeable potassium (up to 860 mg/kg), and organic matter in the arable horizon significantly increases, and acidity decreases. The LF of manure effluents of cattle contributes to a more pronounced increase рНКСl and a more intensive accumulation of organic matter than the LF of pig manure effluents, which may be due to the different chemical composition of manure. Cattle manure contains more Cа and Mg, which lower the pH, as well as lignin and fiber, leading to the accumulation of humus in the soil. The concentration of all studied heavy
metals (HM) in arable land did not exceed the values typical for agrozems of the Kirov region. The content of gross and mobile forms Cu, Cd, Pb in the surveyed agro-ecosystems turned out to be higher than in the background territories. The amount of HM in corn stalks did not exceed the usual content of these elements in plants of uncontaminated territories. The accumulation indices of all studied HM, except Cu, were significantly higher when growing plants on acidic soils. A possible reason for the increased bioavailability of Cu for plants in neutral soils may be the formation of soluble chelate complexes. To prevent environmental pollution in the area of livestock complexes, it is necessary to improve the existing system of animal waste disposal and introduce technologies that allow waste to be transported over long distances.
Keywords: manure runoff, soil pollution, heavy metals, accumulation index, degradation of agrozem
Article published in number 3 for 2022 DOI: 10.25750/1995-4301-2022-3-219-225
Seasonal variation of concentration and net CO2 exchange in the spruce forest ecosystem of the middle taiga
S.V. Zagirova, J.F. Mikhailov
Section: Ecology and climate change
Measurements of CO2 concentration in atmospheric air and CO2 fluxes over the forest canopy were carried out to quantify ecosystem net exchange (NEE) in spruce stands during the growing season of 2017. In the conditions of cool and rainy summer, the rate of net CO2 exchange between the spruce forest and the surface atmosphere varied from -15.0 to 15.0 gCO2 /(m2 · day), the cumulative NEE from May to August was -780 gCO2 /m2 . In the second half of August the spruce forest became a source of CO2 release into the atmosphere. The change in the CO2 concentration in the air column was approaching zero and did not affect the accumulation of ecosystem exchange. Measurements at eight heights of spruce stands showed a gradual decrease in CO2 concentration in the first half of the growing season, the minimum values were noted in July and August, during the period of maximum photosynthesis of forest trees. The main source of CO2 is soil, respectively, the maximum concentrations are noted in the ground layer of air. The amplitude of seasonal fluctuations in the CO2 content in the air at a height of 0.5 m was 92 ppm, at 2.5 m – 67 ppm, and in the crown space did not exceed 47 ppm. The rate of turbulent air mixing and photosynthetic activity of the canopy of the stand determined the daily changes in the concentration gradient according to the altitude profile of the phytocenosis. Decrease of CO2 in the air column 0–30 m after sunrise and before noon corresponded to an increase in net exchange in the ecosystem of forest. The results of one year of observations indicate that the spruce forest ecosystem performs the function of a sink of carbon dioxide, however,
to assess the interannual variability of net exchange, continuous long-term measurements are required.
Keywords: spruce forest, middle taiga, surface layer of atmosphere, carbon dioxide net exchange, eddy-covariance
Article published in number 3 for 2022 DOI: 10.25750/1995-4301-2022-3-226-234
Survival and reproductive value of different cohorts in the muskrat population (Ondatra zibethicus L.)
N.S. Korytin, V.V. Shiryaev
Section: Population ecology
A few demographic parameters of the muskrat population have been obtained. The study is based on data from trapping muskrat samples (total 2018 individuals) and information on the fertility of 868 females. Variation in the cohort’s survival rate and reproductive value were studied for the first time on the basis of the muskrat population age distribution in the Ili River delta. The females specific survival rate was slightly higher than males in all age intervals. Both males and females survival rate was dramatically reduced starting at the age 1+. Maximal specific survival rate in the 0+ – 1+ age interval is typical for animals of the first cohort, minimal – for the second, which is most numerous. The picture of specific survival rate changes as cohort is growing older. In older age classes, the maximum survival rate turn out to last, third cohort. So, in the last age class the largest part of individuals belong to the third cohort (75%). As a result, the largest number of offspring is brought by females of this cohort (1.24–1.57 times more than representatives of the first and second cohorts). This is indicating the highest reproductive value of the third cohort females. No significant discrepancy in the fertility of females from different cohorts were found. That is, differences in the reproductive value of muskrats belonging to different cohorts arise due to the difference in specific survival rate. The number of representatives of the first two cohorts, which survived for the next year, is quite enough to form the population parent number. The muskrat retains the mechanism of forming next year reproductive core, which is typical to small voles, but it does not have a determining value for it.