[en] Short communication

[en] The applicability of the gas thermal chromatography method in radioactivation analysis for the separation of some elements which are identified with difficulty (in the case of instrumental variant): Zn, Se; Cu, Na, As, Sb and Br; Mo, W; Hg, Sm; Cd, La etc., is studied. The empyric dependence between sedimentation temperature on graphite in the form of chloride and the boiling temperature of the Tsub(sed)(deg C)=(30+-5)+(0.62+-0.03)xTsub(boil)(deg C) type, is found. The sublimation enthalpy of cerium elements is also found. The separation is carried out using a thermal chromatographic column of 180x0.7 cm. The completeness of TC separation and extraction of elements in radioactivation analysis depending on the values of sorbent graining, the temperature of starting zones, cooling time, expenses of gaseous reagent, the value of the temperature gradient etc., are determined. The standard devision is experimentally determined, the reason for which is the alteration in the velocity of the carrier gas, the uneven filling of the column with graphite, nonuniform sorbent graining. The obtaining of extreme values by variation is shown. Thermochromatographic separation of elements (in the form of chlorides) is possible if they are different enough in the boiling temperature

[en] The possibility to use thermochromatography (GTC) in radioactivation analysis of biological objects (soil, plants) has been considered Group isolation of certain highly volatile elements from sodium and bromine radionuclides is achieved. The element determination limit, using the instrumental NAA and NAA with GTC application, is evaluated. Advantages of the method and its analytic parameters are discussed

[en] The possibility to use thermochromatography in radioactivation analysis for the study of the composition of low-soluble samples with a highly activated base has been considered. The sample irradiation is realized in reactor with neutron integral flux (0.6-15)x10¹⁶ n/cm². Thermochromatographic separation was carried out after ''cooling'' for 2, 8 and 20 days. The effect of ground sample grainsize and are type on the rate of extraction of gold and other concomitant elements is studied. Comparison of NAA results, when thermochromatography was used, with instrumental NAA is made. It is shown, that the use of thermochromatography reduces element determination limits, when analyzing sulphide ores and rocks. The method can be applied for the separation and determination of the radionuclides:sup(115)Cd-sup(140)La; sup(99)Mo-sup(187)W; sup(65)Zn-sup(46)Sc-sup(152)Sm; sup(141)Ce-sup(59)Fe; sup(197)Hg-sup(239)Np-sup(152)Sm etc

[en] To evaluate the possibility of applying gaseous thermochromatography in radioactivation analysis, the main factors, affecting the processes of sample chlorination, sublimation and thermochromatographic separation of chlorides of certain elements, the determination of which is frequently realized by the method of neutron-activation analysis, have been considered. The behaviour of ¹²⁴Sb, ⁷⁶As, ¹⁹⁸Au, ²⁰³Hg chlorides is studied versus the initial temperature, chlorination duration, flow rate of gas-reagent, sorbent (graphite) graining, the value of temperature gradient, etc

[en] Short note

[en] Full text: Soil is one of the main components of biosphere, which is subject to Man's economic activity from year to year. Unfortunately, during last 50-60years it became an object of the chemization (the treatment of crop by poison chemicals and the usage of mineral fertilizers).Thus, definite pre-conditions are created to migrate to substances applied along the soil horizon. These substances fall into organism of Man and animals through soil-contacting media: plants, air, water. In this respect the instrumental neutron-activation techniques which allows determination of about 40 chemical elements in soils and other objects of environment, with detection limit equal to 0.001-10.0mg/kg and not more than 30% uncertainty, are provided with the Ge -detector (the Canberra firm). The report discusses some metrological points of INAA concerning the objects of environment, in particular, the influence of space-time non-uniformity of chemical element distributions on the reliability of analysis results. The elaborated techniques make it possible to: - establish the elemental composition of soils, cotton, natural waters, mineral fertilizers, aerosol dust of near land layer of various climatic zones of Uzbekistan, including the airs around the Aral sea. - study of the interrelation between the soil elemental composition and the chemism in the evolution of pathological processes - find the correlation between the cotton returns and Mn contents in soils and to elaborate on this base a new way to value the presown grain quality - choose the wall material of ancient monuments of a region, which were not strongly subjected to ecological impact, as standards to monitor the background of chemical elements in soils - value the ecologically agrochemical conditions of soils for main cotton-sawing zones of Uzbekistan - perform a large scale mapping of soils to find the Mn contents and to elaborate the technology of introduction of Mn - containing microfertilizers - estimate the intercorrelation between overall concentrations and their mobility as well as other physical chemical parameters, in particular, the ion potential - select individual bio-geochemical provinces and subregions of biosphere with a high Na and Cl (area round the Aral sea) and Hg, Sb, As-contents (the valley of the Zeravshan river) The report also presents some special problems of agriculture of Uzbekistan

No abstract available

[en] Short note

[en] Antimony content in various subjects of environment, and it's behaviour in the system soil-water-plants-mammals' organs is determined by instrumental neutron activation method. On the basis of statistical data ensured, the sharp increasing of antimony content in plants and in wool of mammals in the regions of ore location is demonstrated. Plants concentrating antimony are determined