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1.
A simple method has been developed that allows a fast determination of the homogeneity of an element M in an alloy, even for minor components. This is done by measuring a ratio of ion currents I, I M/I M’O, whereby M’ is the matrix element, by inductively coupled plasma mass spectrometry (ICP-MS). The method can be used to determine the homogeneity of one component in a binary alloy and allows to estimate the sample size necessary to minimise uncertainty contributions due to inhomogeneity in the analysis of such an alloy. In this work the homogeneity of a niobium/0.1% zirconium alloy was determined on 1 mg samples. Accurate weighings of these small samples are not required, as the method is based on the measurement of the niobium/zirconium amount ratio in the dissolved samples. As this ratio is fairly large, the Zr/NbO amount ratio was measured instead to decrease the magnitude of the measured ratio. This ratio was found to be sufficiently stable over time for homogeneity testing. In this particular case the Zr/NbO ratio in the samples was found to vary by 0.049 relative for a 1 mg samples size. Received: 30 November 1998 / Revised: 22 March 1999 / Accepted: 27 March 1999  相似文献   

2.
The metals intake through tobacco smoking is associated with adverse effects for human health. The present study was aimed to understand the effects of biri smoking on smoker’s serum metal profile. Seven metals, cadmium (Cd), nickel (Ni), lead (Pb), chromium (Cr), copper (Cu), iron (Fe) and zinc (Zn), were analysed in serum samples of 20 biri smokers and 20 non-smokers from North India. The Cd, Ni, Pb, Cr and Cu concentrations were higher while Fe and Zn concentrations were lower in smokers compared to non-smokers. The Fe concentrations, the highest among all metals, seemed to be unassociated with the smoking activity. This study indicated that biri smoking is a contributor to the body burden of Cd, Ni, Cu and Cr in the smoker’s body. The Cd, Ni, Cu and Fe concentrations are non-significantly associated with the age of smokers at p < 0.01 significance level, whereas Pb and Cr concentrations increase and Zn concentrations decrease with the increase in the age of smokers. Serum metal concentrations in the smoker subjects of North India are higher compared to the results of other similar studies. This could be linked to the poor quality of tobacco used in biri. We recommend conducting more detailed and controlled studies in this regard as a smoker is also subjected to other sources of exposure to metals.  相似文献   

3.
We demonstrate a high-precision measurement of the isotopomer abundance ratio 14N(15)N(16)O/15N(14)N(16)O/14N(14)N(16)O (approximately 0.37/0.37/100) using three wavelength-modulated 2 microm diode lasers combined with a multipass cell which provides different optical pathlengths of 100 and 1 m to compensate the large abundance difference. A set of absorption lines for which the absorbances have almost the same temperature dependence are selected so that the effect of a change in gas temperature is minimized. The test experiment using pure nearly natural-abundance N(2)O samples showed that the site-selective 15N/14N ratios can be measured relative to a reference material with a precision of +/-3 x 10(-4) (+/-0.3 per thousand) in approximately 2 h.  相似文献   

4.
In order to determine,99Tc in the atmosphere, we analyzed a dried-up deposition sample obtained from rain and dry fallout. We carried out tracer experiments to investigate the loss of99Tc during preparation of the sample by evaporation and drying and to examine a suitable separation method for measurement of the nuclide in the sample by using ICP-MS. The results showed no remarkable reduction of Tc during evaporation to dryness. The volatilization and trapping method with a combustion apparatus gave a clear and easy separation of Tc with a recovery of 77%.  相似文献   

5.
A new method for determining the O/U ratio in uranium oxide is described. The method consists of dissolving an accurately weighed sample in a known excess of ceric ammonium nitrate in 2N perchloric acid at room temperature and estimating the unreacted Ce/IV/ with benzohydroxamic acid. A standard deviation of 0.0016 for ten estimations is observed.  相似文献   

6.
金属氧化物对十氯联苯的降解研究   总被引:1,自引:0,他引:1  
分别以市售的Fe2O3、MgO和CaO为催化剂,对十氯联苯(CB209)进行了催化降解研究.结果表明,MgO对CB209的降解具有较高的活性.在反应温度为300℃,反应时间为60 min时,MgO对CB209的降解效率达到98.9%.进一步研究表明,MgO催化降解CB209的动力学符合准一级动力学反应.通过GC-MS和GC-ECD,并结合衍生化实验,检测到九氯联苯、五氯苯和四氯苯、五氯苯酚、四氯苯酚和三氯苯酚等降解产物,进而推测出MgO催化降解CB209的过程中存在相互竞争的反应路径:氧化反应、碳碳桥键断裂和加氢脱氯.  相似文献   

7.
The morphology, particle size, and thermochemical properties of the surface of oxides Al2O3, NiO, TiO2, ZnO, and ZrO2 obtained by the wire electroexplosion method were studied. The nanoparticles are spherical, with a mean diameter of 54–86 nm depending on the nature of the oxide. The hydrophilicity of the surface of metal oxide nanopowders was found to change in the series NiO-ZrO2-TiO2-ZnO-Al2O3. Nanocomposites with widely varied compositions were obtained from butyl methacrylate copolymer with 5 wt % methacrylic acid and the oxides under study. The enthalpies of dissolution of the composites in chloroform were determined by Calvet calorimetry. The enthalpies of copolymer mixing with oxides were calculated using the thermochemical cycle. The limiting enthalpies of copolymer adhesion to the oxide surface were calculated from the thermochemical data. The limiting adhesion enthalpy was shown to be negative for all oxides under study; these values decreased in magnitude as the surface hydrophilicity increased. The results were analyzed from the viewpoint of balance between the specific and dispersion interactions at the interface.  相似文献   

8.
On the Use of ICP-MS for Measuring Plutonium in Urine   总被引:1,自引:0,他引:1  
The analytical protocols currently used to measure plutonium in urinary excretion consist of radiochemical purification, the source preparation by electroplating and alpha spectrometry measurements. Such a procedure is of limited relevance to the individual monitoring of workers exposed to plutonium and mixed oxides. The use of ICP-MS, which takes much shorter counting time, was investigated with the aim of assessing the capabilities of this analytical tool for the determination of urinary excretion of plutonium. It has been shown that the detection level of 1 mBq·1-1 could be achieved after a radiochemical purification process for a standard ICP-MS set-up.  相似文献   

9.
The potential of atomic XAFS (AXAFS) to directly probe the catalytic performances of a set of supported metal oxide catalysts has been explored for the first time. For this purpose, a series of 1 wt % supported vanadium oxide catalysts have been prepared differing in their oxidic support material (SiO2, Al2O3, Nb2O5, and ZrO2). Previous characterization results have shown that these catalysts contain the same molecular structure on all supports, i.e., a monomeric VO4 species. It was found that the catalytic activity for the selective oxidation of methanol to formaldehyde and the oxidative dehydrogenation of propane to propene increases in the order SiO2 < Al2O3 < Nb2O5 < ZrO2. The opposite trend was observed for the dehydrogenation of propane to propene in the absence of oxygen. Interestingly, the intensity of the Fourier transform AXAFS peak decreases in the same order. This can be interpreted by an increase in the binding energy of the vanadium valence orbitals when the ionicity of the support (increasing electron charge on the support oxygen atoms) increases. Moreover, detailed EXAFS analysis shows a systematic decrease of the V-Ob(-M(support)) and an increase of a the V-O(H) bond length, when going from SiO2 to ZrO2. This implies a more reactive OH group for ZrO2, in line with the catalytic data. These results show that the electronic structure and consequently the catalytic behavior of the VO4 cluster depend on the ionicity of the support oxide. These results demonstrate that AXAFS spectroscopy can be used to understand and predict the catalytic performances of supported metal oxide catalysts. Furthermore, it enables the user to gather quantitative insight in metal oxide support interactions.  相似文献   

10.
Journal of Radioanalytical and Nuclear Chemistry - We demonstrated that bromine in ethyl acetate can selectively separate metallic contents in lanthanide metal-oxide mixtures for analysis, which...  相似文献   

11.
In this work we present the utilization of the heterometallic alkoxide [FeCl{Ti(2)(OPr(i))(9)}] as the first sol-gel single-source precursor to achieve nanocomposites made of iron and titanium oxides incorporated into Porous Vycor Glass (PVG). The nanocomposites were prepared by the impregnation of the precursor in a PVG plate followed by hydrolysis reactions. Different samples were obtained by further thermal treatment of the hydrolyzed sample. The nanocomposites were characterized by UV-vis-NIR, Raman and EPR spectroscopies, XRD and TEM. The results indicate that the room-temperature hydrolyzed samples are formed by nanoparticles of FeOOH and brookite-TiO(2) embedded on a glassy matrix. After the heat treatment at temperatures above 900 degrees C, a pseudobrookite Fe(2)TiO(5) was formed. All samples present high transparency and homogeneity. The results showed here indicate that the sol-gel process using the single-source precursor [FeCl{Ti(2)(OPr(i))(9)}] should be a novel and efficient approach to the preparation of nanometric Fe/Ti oxides incorporated into a glassy matrix.  相似文献   

12.
A new method was developed for the determination of trace anions in chloride-rich samples via ion chromatography by reducing the concentration of chloride ions using silver oxide as a precipitating reagent. In this method the sample pretreatment was started with the addition of silver oxide powder followed by 8 min of stirring and 2 min of centrifugation at a speed of 1500 rpm. The supernatant was diluted with a 1:10 ratio using deionized water and filtered with a 0.22 microm NC filter. All the samples were analyzed in a Dionex ICS-2500 system with an ED50 electrochemical detector in conductivity mode. On the basis of Dionex IonPac AG18 (50 mm x 2 mm) and AS18 (250 mm x 2 mm) columns, 25 AL sample filtrate was eluted isocratically with a mobile phase of 32 mmol/L NaOH at a flow rate of 0.25 mL/ min and each eluted analyte was detected after postcolumn suppression via a Dionex anion suppressor ULTRA II (2 mm). With this method most of the common anions at mg/kg level in chloride-rich samples can be accurately quantified. By controlling the equivalent weight ratio of silver oxide to chloride in sample solutions and the time of pretreatment, the free silver and chloride ions in the sample solution are optimized such that most coexisting common anions can be determined simultaneously.  相似文献   

13.
ICP-MS测量环境样品中铀的非质谱干扰内标校正研究   总被引:3,自引:0,他引:3  
内标的合理应用直接关系到测量结果的可靠性,通过外标与内标校正相结合的方法,实验研究了Y,Rh,In,Tb,Yb,Tl,Bi,Re作为内标对ICP-MS测量铀的非质谱干扰的校正效果。对于非抑制/增强基体效应,各内标元素校正结果明显优于无内标校正结果,高质量数内标元素Tb,Yb,Re,Tl,Bi可获得较好的校正效果,校正偏差优于5%,其中以Tl为最佳;对于盐度较高的样品溶液,由于基体对待测元素和内标元素产生了明显不同的抑制/增强效应,因此各内标校正结果均不理想,这表明内标对可溶性固体引起的抑制/增强效应的校正能力有限。在铀的测量中,对于含盐度在300~500μg/mL的样品,内标校正造成的偏差可达到5%~10%;对于盐度在500μg/mL以上的样品,内标校正造成的偏差很可能超过10%或者更高。  相似文献   

14.
A rapid and simple analytical method for the determination of transition metals and rare earth elements at sub-ng/g levels in alkaline and earth alkaline salt matrices was developed. Automated solid-phase extraction was utilized for matrix separation and analyte preconcentration from highly concentrated brine solutions. The HPLC system used was equipped with a chelation column packed with an iminodiacetate-based resin. Detection was accomplished by means of high-resolution inductively-coupled plasma mass spectrometry (ICP-MS), which allowed quasi-simultaneous multi-element determinations. A microconcentric nebulizer was employed for HR-ICP-MS to determine the elements of interest in small volumes of sample extracts. The method was shown to be very sensitive with limits of quantification in the range of 1–40 ng/g for all investigated elements. The method exhibited excellent precisions, high analyte recoveries, linear responses of least three orders of magnitude, high accuracy and low contamination susceptibility. A comparison of automated solid-phase extraction with methodologies utilizing traditional liquid-liquid extraction showed that the former offered similar analytical performance but was clearly easier to use and faster to perform, resulting in substantial time, labor and cost savings. Received: 12 February 1999 / Revised: 23 March 1999 / Accepted: 25 March 1999  相似文献   

15.
A rapid and simple analytical method for the determination of transition metals and rare earth elements at sub-ng/g levels in alkaline and earth alkaline salt matrices was developed. Automated solid-phase extraction was utilized for matrix separation and analyte preconcentration from highly concentrated brine solutions. The HPLC system used was equipped with a chelation column packed with an iminodiacetate-based resin. Detection was accomplished by means of high-resolution inductively-coupled plasma mass spectrometry (ICP-MS), which allowed quasi-simultaneous multi-element determinations. A microconcentric nebulizer was employed for HR-ICP-MS to determine the elements of interest in small volumes of sample extracts. The method was shown to be very sensitive with limits of quantification in the range of 1–40 ng/g for all investigated elements. The method exhibited excellent precisions, high analyte recoveries, linear responses of least three orders of magnitude, high accuracy and low contamination susceptibility. A comparison of automated solid-phase extraction with methodologies utilizing traditional liquid-liquid extraction showed that the former offered similar analytical performance but was clearly easier to use and faster to perform, resulting in substantial time, labor and cost savings.  相似文献   

16.
Isotope dilution is a useful technique to measure the labile metal pool, which is the amount of metal in soil in rapid equilibrium (<7 days) with the soil solution. This is normally performed by equilibrating soil with a metal isotope, and sampling the labile metal pool by using an extraction (E value), or by growing plants (L value). For Cu, this procedure is problematic for E values, and impossible for L values, due to the short half-life of the 64Cu radioisotope (12.4 h), which makes access and handling very difficult. We therefore developed a technique using enriched 65Cu stable isotope and measurement of 63Cu/65Cu ratios by quadrupole inductively coupled plasma mass spectrometry (ICP-MS) to measure labile pools of Cu in soils using E value techniques. Mass spectral interferences in detection of 63Cu/65Cu ratios in soil extracts were found to be minimal. Isotope ratios determined by quadrupole ICP-MS compared well to those determined by high-resolution (magnetic sector) ICP-MS. E values determined using the stable isotope technique compared well to those determined using the radioisotope for both uncontaminated and Cu-contaminated soils.  相似文献   

17.
Kitamura Y  Ogawa H  Oka K 《Talanta》2003,61(5):717-724
Nitric oxide (NO) is an important mediator responsible for numerous physiological phenomena. Transient levels of NO in biological systems usually range from nanomolar to micromolar concentrations, with a rapid return to basal levels normally seen following these increases. Because NO can diffuse only over a local area in limited time due to such low levels of production and due to its short life-time prior to degradation, high spatial and temporal resolutions are required for direct and continuous NO measurement if the physiological role of NO is to be investigated in any system. For such purposes, analytical methods based on bio-imaging and electrochemical techniques for the measurement of NO are useful. In this paper, we describe the successful application of these methods to a number of biological systems. Specifically, complementary application of these methods demonstrate that it is possible to detect real-time NO production from nervous tissue with high spatial and temporal resolutions.  相似文献   

18.
Catalytic dehydration of ethanol using transition metal oxide catalysts   总被引:9,自引:0,他引:9  
The aim of this work is to study catalytic ethanol dehydration using different prepared catalysts, which include Fe(2)O(3), Mn(2)O(3), and calcined physical mixtures of both ferric and manganese oxides with alumina and/or silica gel. The physicochemical properties of these catalysts were investigated via X-ray powder diffraction (XRD), acidity measurement, and nitrogen adsorption-desorption at -196 degrees C. The catalytic activities of such catalysts were tested through conversion of ethanol at 200-500 degrees C using a catalytic flow system operated under atmospheric pressure. The results obtained indicated that the dehydration reaction on the catalyst relies on surface acidity, whereas the ethylene production selectivity depends on the catalyst chemical constituents.  相似文献   

19.
ICP-MS法测定金属镝中的非稀土杂质   总被引:1,自引:0,他引:1  
用ICP-MS法对高纯金属镝中10种非稀土杂质Al、Fe、Ni、Ti、Co、Cd、Mn、Pb、Cu、Ba、Mg的测定进行了研究。估算了元素的测定下限;研究了酸度影响;并进行了不同方法的结果对照实验;采用In作内标,方法的加标回收率在80.5%-110.2%之间,相对标准偏差低于12%。  相似文献   

20.
Total reflection X-ray fluorescence spectroscopy (TXRF) has been used in combination with synchrotron radiation in order to determine detection limits and lowest limits of concentration of trace elements in metal matrices. Two applications on irradiated material are described, where the TXRF method has some advantages, as compared to other detection methods, because only few micrograms of material is needed for the measurements. The first application is devoted to radiation damage studies on first wall material of future fusion reactors. Therefore, metal foils were irradiated with 590 MeV protons at PSI and the transmutational elements produced in the foils were measured. The second application is the assessment of radiation damage of core components in a nuclear power plant, e.g. the reactor pressure vessel. This is performed by the determination of the fast neutron fluence on the components using an activation reaction of 93Nb which is a trace element in most reactor steels. Detection limits of a few picograms have been found in the experiments.  相似文献   

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