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121.
A simple and selective method for rapid and efficient concentration and determination of μg l−1 levels of Au(III) ions in aqueous solution using octadecyl silica membrane disks modified by pentathia-15-crown-5 and flame atomic absorption spectrometry is presented. The influence of flow rates of eluent and sample solution, amount of ligand, types and least amount of eluent for elution of Au from disks were investigated. Break through volume and limit of detection of the membrane disks modified by 5 mg of the thiacrown ether was found to be 2.0 l and 1.0 μg l−1, respectively. The effects of various cationic interferences on percent recovery of gold were studied. The method was successfully applied for the determinations of gold in some pharmaceutical samples and for the recovery of trace Au3+ ions from synthetic and water samples. 相似文献
122.
硅的原子吸收光谱分析进展 总被引:5,自引:0,他引:5
对近十年来用原子吸收光谱法测定硅的情况进行评述.重点介绍用石墨炉测定硅时,为了避免硅与石墨炉中碳形成难熔碳化硅影响测定硅的灵敏度而使用的各种化学改进剂,涂层石墨管和一些新的实验技术.引用参考文献42篇. 相似文献
123.
Tapping mode atomic force microscope has been applied to observe single-chain PMMAparticles which were stored for six months at room temperature after sprayed from verydilute solutions in good solvents, good/poor mixed solvents, and a theta solvent. Monodis-perse PMMA standards of molecular weights ranging from 7.90×10~4 to 1.3×10~6 wereused to investigate the effect of molecular weight oh the size of the single-chain PMMAparticles. These single-chain particles showed close to spherical shapes. The morphologyof single-chain PMMA particles of a given molecular weight was found to be identical inspite of different solvents used for solution spraying. Molecular weigh dependence of theparticle dimension was also found. The diameters of single-chain PMMA particles aftercorrection of tlp-geometry effect were compared to the values estimated from molecularweight and density. 相似文献
124.
The analytical performance of a microwave plasma torch was improved through mechanical alterations. Several problems reported in earlier designs were addressed: the ignition and stabilization of a helium plasma in the MPT was difficult; high powers were required to both ignite and operate the plasma; otherwise, the plasma would erratically change from an annular to a filament type discharge. In the new torch, the helium discharge was stabilized by replacing the copper central tube with one made of quartz. In addition, air entrainment was alleviated through use of a sheathing gas. This modification simplified the background mass spectrum and raised the effective ionization temperature of the discharge. A detailed schematic diagram of the new microwave plasma torch is presented. 相似文献
125.
An analytical procedure for dissolving wolframite in order to determine trace elements by atomic absorption is reported. After decomposition of the mineral by alkaline fusion, the cooled flux is dissolved by heating with aqua regia. The finely crystalline precipitate of tungstite, which forms on standing, is filtered and dissolved by heating with aqua regia. Tungstite forms again in the latter solution and the filtration and solubilization are repeated until the solution contains negligible amounts of trace elements. Following this procedure, trace elements in 35 samples of natural wolframite have been dissolved and the solutions obtained have been analyzed by atomic absorption spectrometry for Fe, Mn, Cu, Zn, Pb, Co, Ni and Cd. 相似文献
126.
Gold nanoparticles in polyelectrolyte multilayers film can be easily prepared by repeating immersion of a substrate in poly(diallyl dimethylammonium) chloride (PDDA)-AuCl4− complexes solution followed by reduction Au3+ through heating. UV-vis spectroscopy, cyclic voltammetry (CV) and tapping-mode atomic force microscopy (AFM) are used to confirm the successful construction of the polyelectrolyte multilayers film and the formation of gold nanoparticles. The multilayers film shows electrocatalytic activity to dioxygen reduction. 相似文献
127.
128.
The microwave acid digestion method was applied to the decomposition of rock samples and optimum conditions were investigated. Samples of 10–100 mg were decomposed by changing the amount and composition of acid, heating time and number of reheating steps and then the concentrations of Si, Fe, Mn, Na, K and Mg in these samples were measured. The concentrations agreed with reported values when 10 mg of sample were decomposed by heating for 60 s with 0.3 ml of concentrated HNO3 and 0.1 ml of concentrated HF. Similarly, 100 mg of sample were also decomposed successfully by heating for 45–110 s with 0.3–1.0 ml of concentrated HNO3 and 0.4–0.7 ml of concentrated HF. It is concluded that the microwave acid digestion method decomposes rock samples with a very short heating time and with small amount of reagents compared with methods using conventional sealed PTFE vessels, which require several hours for the heating step and several millilitres of reagents. 相似文献
129.
Feng Zhao Yu-Kou Du Ping Yang Ji’an Tang Xing-Chang Li 《Colloid and polymer science》2005,283(12):1361-1365
In the present study, the structure and morphology of single sodium poly(styrenesulfonate) (PSS) molecules adsorbed to mica
surface from the natural aqueous solution is investigated using atomic force microscopy technique. Results show that single
PSS molecules are observed which show a morphology of wormlike coils. Meanwhile, single sodium poly(styrenesulfonate) (PSS)/Hexadecyltrimethylammonium
bromide (CTAB) complexes deposited on mica from the air–water interface are also observed. However, the PSS/CTA+ complexes show different conformations by appearing in the morphology of circular patches. Experimental data are in fair
agreement with the theoretical analysis. 相似文献
130.
离子浮选石墨炉原子吸收光谱法测定水中痕量Cr(Ⅵ)/Cr(Ⅲ) 总被引:10,自引:0,他引:10
本文以二苯卡巴肼(DPCI)和十二烷基硫酸钠(SLS)为浮选剂研究了分离浓缩(Cr(Ⅵ)的最佳条件,建立了水中痕量络的形态分析方法。该方法简单、快速、检测限0.03μgL^-1,变异系九小于4%,200mL水样中含NO350,Na^+,Mg^2+40,Cl28,D,Ca^2+,SO410,CO39,Al^2+,Co^2+,Ni62+5,Mn^2,Pb^2+2.5,Fe^3+0.2mg不影响测定。方 相似文献