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21.
Solid-phase extraction clean-up of soil and sediment extracts for the determination of various types of pollutants in a single run 总被引:6,自引:0,他引:6
Dabrowska H Dabrowski L Biziuk M Gaca J Namieśnik J 《Journal of chromatography. A》2003,1003(1-2):29-42
A new sample clean-up procedure based on solid-phase extraction (SPE) sorbents was proposed for the determination of pesticides, polycyclic aromatic hydrocarbons and polychlorinated biphenyls in soils and sediments. The main purpose of the research was to find a combination of sorbents for the SPE method that would permit the determination of many types of analytes (polycyclic aromatic hydrocarbons, polychlorinated biphenyls, N-, P- and Cl-containing pesticides) in a single run. Elution profiles for both the analytes and the interfering components were determined for several types of SPE sorbents (alumina, silica and surface-modified silica) and combinations of them. The efficiency of the clean-up method developed was evaluated using real soil samples. 相似文献
22.
A. Jasik W. Wierzchowski J. Muszalski J. Gaca M. Wójcik K. Pierściński 《Journal of Crystal Growth》2009,311(16):3975-3977
The non-doped AlAs/GaAs distributed Bragg reflectors (DBRs) with density of misfit dislocation (MD) close to zero had been obtained. The reduction of MD density was achieved by increasing temperature distribution homogeneity on the growing crystal in consequence of higher rotation rate of the wafer. Two structures of DBR were crystallized using molecular beam epitaxy (MBE) under the same optimal growth condition. The growth runs differ only in the rotation rate of the wafers. X-ray topograph showed no residual MDs in case of faster rotation. The DBR structure with residual MD density is still highly strained. No additional relaxation process has occurred, what was confirmed by an angular position of DBR zeroth-order peak on high-resolution X-ray diffractometry (HRXRD) rocking curve. 相似文献
23.
J. W. Mietelski P. Szwałko E. Tomankiewicz P. Gaca S. Małek J. Barszcz S. Grabowska 《Journal of Radioanalytical and Nuclear Chemistry》2005,262(3):645-660
Results for 137Cs, 40K, 90Sr, 238,239+240Pu, 241Am and 243+244Cm measurements in plant, insects and forest litter samples collected at three sites in Poland are presented. New results are compared with some existing data for locations examined during previous studies. Insect samples were introduced now for the first time. Relatively high activities of 90Sr were noticed for spruce bark beetle (Ips typographus) and those for 137Cs, plutonium and 241Am for forest dung beetle (Anoplotrupes stercorosus). Faster than caused by physical decay decrease of radiocesium activity was noticed for the majority of plant and litter samples. The results for 239+240Pu for litter were similar to previous results, but the activities of 238Pu were smaller. The activity ratio between 241Am and 239+240Pu was found lower than expected for known proportions between global and Chernobyl fallout. Thus a kind of dynamic behavior of Pu and Am in the forest ecosystem is concluded. Transfer factors and aggregation coefficients were estimated and discussed for both plants and insects as well as between insects and the part of plants (or litter) they feed on. Many of them were never presented before.The authors are thankful to the Polish State Committee for Scientific Research for financial support of this investigation, Grant No. PG04 07520. 相似文献
24.
J. W. Mietelski L. Kitowski P. Gaca S. Grabowska E. Tomankiewicz P. Szwałko 《Journal of Radioanalytical and Nuclear Chemistry》2006,270(1):131-135
Summary The present study focused on analyzing samples of bones, livers and kidneys of European white-tailed eagles (Halia?tus albicilla) and lesser-spotted eagle (Aquila pomarina). Bone samples were collected for both species, from 7 and 2 individuals, respectively, whereas liver and kidney samples
for white-tailed eagle species only, 2 and 1 individuals, respectively. The samples were analyzed for the presence of gamma-emitters
and then for 90Sr, 238Pu, 239+240Pu and 241Am. The applied radiochemical method is presented. Activity concentration in ashen bones (600 °C) for 90Sr ranged from 4.6±1.2 to 31.0±2.5 Bq/kg, for 239+240Pu from <1.7 to 21±4 mBq/kg, for 238Pu from <2.7 to 6.5±1.3 mBq/kg and for 241Am from <1.2 to 6.5±4.4 mBq/kg. Relatively high 239+240Pu activity concentration of 78±9 mBq/kg (for fresh weight) was recorded in a single kidney sample. The liver samples showed
activities of magnitude at least one order lower. No clear correlations were found between the activities of different radionuclides. 相似文献
25.
A new method for the determination of linoleic acid (LA) in toothpaste by a routine analysis has been proposed. Studies were based on the ISO 5509 procedure, which was modified for the purpose of LA determination in the toothpaste. Gas chromatography (GC) was employed for the qualitative and quantitative determination of linoleic acid methyl ester. The content of LA (5.31%) in sunflower oil added to the toothpaste composition (0.5%) was determined, and then the optimization studies for the determination of LA in the toothpaste samples were carried out. The relative standard deviation (RSD) of the procedure developed was 9.96% (n = 9). The quantitative analysis showed that the content of LA in the toothpaste samples studied was 0.0258 +/- 0.0011%. The detection limit of LA in toothpaste was approximately 0.001%. 相似文献
26.
J. W. Mietelski P. Szwako E. Tomankiewicz P. Gaca S. Maek J. Barszcz S. Grabowska 《Journal of Radioanalytical and Nuclear Chemistry》2004,262(3):645-660
Results for 137Cs, 40K, 90Sr, 238,239+240Pu, 241Am and 243+244Cm measurements in plant, insects and forest litter samples collected at three sites in Poland are presented. New results are compared with some existing data for locations examined during previous studies. Insect samples were introduced now for the first time. Relatively high activities of 90Sr were noticed for spruce bark beetle (Ips typographus) and those for 137Cs, plutonium and 241Am for forest dung beetle (Anoplotrupes stercorosus). Faster than caused by physical decay decrease of radiocesium activity was noticed for the majority of plant and litter samples. The results for 239+240Pu for litter were similar to previous results, but the activities of 238Pu were smaller. The activity ratio between 241Am and 239+240Pu was found lower than expected for known proportions between global and Chernobyl fallout. Thus a kind of dynamic behavior of Pu and Am in the forest ecosystem is concluded. Transfer factors and aggregation coefficients were estimated and discussed for both plants and insects as well as between insects and the part of plants (or litter) they feed on. Many of them were never presented before.The authors are thankful to the Polish State Committee for Scientific Research for financial support of this investigation, Grant No. PG04 07520. 相似文献
27.
Joanna Pietrasik Magdalena Gaca Lidia Okrasa Olivier Gain 《European Polymer Journal》2009,45(12):3317-3325
The molecular dynamics of carboxylated acrylonitrile-butadiene rubber - silica hybrid materials was investigated. Silica hybrids were formed in situ rubber matrix using varied amounts of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (DAMS), serving also as a cross-linker. Filler-filler and filler-rubber interactions were present, due to the specific nature of these materials. It was found that the amounts of added aminosilane determined the cross-linking density of obtained materials and was the highest with 20 phr DAMS used. The cross-links had ionic nature. Dielectric relaxation spectroscopy (DRS) revealed β, α and α′ relaxation processes. The β relaxation, correlated with the mobility of polymer side groups, was influenced by the weak interaction between both acrylonitrile and carboxylic groups of the rubber and silanol groups of silica. The activation energy for that relaxation was similar for all materials (∼32 kJ mol−1). Both DRS and dynamical mechanical analysis (DMA) demonstrated that the amount of in situ formed silica filler did not significantly influence either the temperature of the α relaxation (correlated with glass transition) or its activation energy. Therefore, that relaxation was caused by free polymer chains, not attached to the silica particles. Similar values of glass transition temperature (Tg) for all hybrids were confirmed by DSC. It appeared that the amplitude of tangent delta (DMA) within Tg was dependent on silica amount. Detected at higher temperature α′ relaxation resulted from the presence of domains, where polymer chains were affected by silica network, geometrical restrictions and morphology of the silica-rich domains. 相似文献