种植青海大黄中微量元素研究

青海地道中药材“西宁大黄”野生资源濒临枯竭,人工种植规模不断扩大。定期采集青海西宁及邻近地区两年生种植大黄,跟踪分析了其微量无素铜、锌、铁、锰、铬,为地道西宁大黄资源的可持续开发和利用提供科学依据。研究表明,种植大黄中微量元素铁、锌、铜、锰的有效积累以及土壤地球化学环境中的微量元素锌、锰、铜对种植大黄的生长具有重要的作用和意义。     

食用菌类中矿物质元素的研究

用火焰原子吸收分光光度法对广东清远笔架山的 1 7种食用菌、 2种木耳及灵芝中赤芝的 8种矿物质元素进行了测定。结果表明 ,食用菌类是优质食品 ,富含对人体有益的微量元素 ,有较高营养价值     

绿茶和红茶中微量元素初级形态含量的研究

本文采用沸水浸泡法对茶叶的初级形态进行分离 ,原子吸收光谱法测定了绿茶和红茶初级形态中 8种微量元素含量 ,计算并讨论了微量元素初级形态分析参数 ,获得茶叶中微量元素初级形态的有关信息。结果表明 ,绿茶和红茶中 8种微量元素初级形态含量各有差异 ,初级形态分析参数自符合程度为87.2 0 %— 10 3.73% ,样品的回收率为 87.1%— 10 2 %。     

Trace element determination in beauty products by k0-instrumental neutron activation analysis

A recent study on trace elements in beauty products and cosmetics sold on the Asian market has shown the presence of high levels of U, Th and rare earth elements in so called “Hormesis cosmetics.” For the purpose of comparison, some more information about trace elements in European cosmetics would be useful. In this paper the results obtained using k ₀-standardised Instrumental Neutron Activation Analysis (k ₀-INAA) for more than 20 trace elements in 20 different beauty products collected from the European market are presented. We found traces of Ba, As and Sb which is in breach with European legislation. For some of the other elements like Cr and Co further speciation is needed in order to evaluate their presence in beauty products.     

Neutron activation analysis of Ca,Cl, K,Mg, Mn,Na, P,and Sr contents in the crowns of human permanent teeth

The effect of age and gender on chemical element contents in intact crowns of permanent teeth of 84 apparently healthy 15–55 year old women (n = 38) and men (n = 46) was investigated. Mass fractions of Ca, Cl, K, Mg, Mn, Na, P, and Sr in crowns were determined by instrumental neutron activation analysis using short-lived radionuclides. Mean values (M ± SΕΜ) for female and male combined were (on dry weight basis): 350 ± 5 g/kg, 2920 ± 150 mg/kg, 839 ± 80 mg/kg, 4880 ± 240 mg/kg, 3.20 ± 0.30 mg/kg, 6240 ± 140 mg/kg, 181 ± 4 g/kg, and 293 ± 24 mg/kg respectively. A statistically significant decrease of Sr (P ≤ 0.01) and increase of Na (P ≤ 0.01) content in the tooth crowns with age was found for women. Sex-related comparison did not show any differences.     

Vacuum ultraviolet laser-induced breakdown spectroscopy analysis of polymers

Laser-induced breakdown spectroscopy (LIBS) in the vacuum ultraviolet range (VUV, λ < 200 nm) is employed for the detection of trace elements in polyethylene (PE) that are difficult to detect in the UV/VIS range. For effective laser ablation of PE, we use a F₂ laser (wavelength λ = 157 nm) with a laser pulse length of 20 ns, a pulse energy up to 50 mJ, and pulse repetition rate of 10 Hz. The optical radiation of the laser-induced plasma is measured by a VUV spectrometer with detection range down to λ = 115 nm. A gated photon-counting system is used to acquire time-resolved spectra. From LIBS measurements of certified polymer reference materials, we obtained a limit of detection (LOD) of 50 µg/g for sulphur and 215 µg/g for zinc, respectively.The VUV LIBS spectra of PE are dominated by strong emission lines of neutral and ionized carbon atoms. From time-resolved measurements of the carbon line intensities, we determine the temporal evolution of the electronic plasma temperature, T_e. For this, we use Saha–Boltzmann plots with the electron density in the plasma, N_e, derived from the broadening of the hydrogen H-α line. With the parameters T_e and N_e, we calculate the intensity ratio of the atomic sulphur and carbon lines at 180.7 nm and at 175.2 nm, respectively. The calculated intensity ratios are in good agreement with the experimentally measured results.     

ICP-MS法测定磁致冷材料-钆硅锗系合金中Mo、 Mn、 Al、 V、 Ni、 Cu、 Ga、 Fe

建立了ICP-MS法测定磁致冷材料-钆硅锗系合金中Mo、 Mn、 Al、 V、 Ni、 Cu、 Ga、 Fe八种痕量杂质元素的方法, 并对ICP-MS工作参数及条件进行了优化. 方法的检出限为0.1～0.6 ng/mL, 测定下限为0.5～3 ng/mL, 回收率在95.5%～109%, 相对标准偏差(n=11)为1.3%～7.6%. 采用该方法对磁致冷材料-钆硅锗系合金实际样品进行了分析, 结果表明精密度和准确度均满足痕量分析的要求.     

原子核强度电势和原子价层电量对元素电负性的标度

根据万有引力势与电势的关系式和系统的对比质电比(单位电量的质量)的物理意义, 定义了系统的强度电势——单位质量的电势. 研究表明, 元素电负性XSc与原子核在原子边界面上的强度电势Vic和价层电子电量qcj成线性关系. 采用回归分析法, 对周期表中除零族、氢及放射性元素之外的77种元素的Pauling电负性(XP)进行回归分析, 得到了一个无量纲的综合性的电负性计算公式, 相关系数(R=0.9844)和回归方程F检验的显著性水平(Sig.=0.0000)表明, XSc与Vic和qcj密切相关, 77种元素的拟合值与XP十分接近, 平均绝对误差仅为0.084; 并预测出较为合理的稀有气体元素的电负性. 用该式可以方便而更准确地计算除氢以外的所有元素的电负性; 同时也给出一条获取离子电负性和基团电负性的新途径.     

Determination of trace amounts of sodium and lithium in zirconium dioxide (ZrO2) using liquid electrode plasma optical emission spectrometry

This paper describes a quantitative measurement of trace elements (Na, Li) in high purity zirconium dioxide powder using liquid electrode plasma optical emission spectrometry (LEP-OES). Conventionally, for such type of measurements, inductively coupled plasma optical emission spectrometry (ICP-OES) is frequently employed. The detection limits of elements in zirconium by ICP-OES are degraded due to the spectra interference between the trace elements and zirconium of the matrix, because zirconium is a line rich element in spectra obtained by ICP-OES. LEP-OES is an elemental analysis method developed by the authors. The measurement principle is simple, as follows. Sample solution is put into a narrow channel on a small cuvette and voltage pulse is applied from both ends of the channel. At the center of the channel which is made narrower, the voltage and current are concentrated there, and plasma is generated. From the emission of the plasma, the quantitative analysis of the elements in the solution is achieved. The LEP-OES has the property that the emission of zirconium is relatively weak, so that highly sensitive measurement of trace elements in zirconium matrix can be conducted without interference. Sample solution is prepared by dissolving high purity zirconium dioxide powder and trace amounts of Na or Li with sulfuric acid. The voltage dependence and the pulse width dependence of optical emission spectra are also investigated. With increase of the voltage or the pulse width, the ratio of emission intensities of Na to those of hydrogen increases. This suggests that the ratio of sensitivity of two elements is variable, that means the element selectivity is controllable to some extent by the measurement conditions in LEP-OES. In the case of Na and H, the ratio can be controlled from 7.4 to 21.6%. Finally, the detection limits (3S.D.) of the trace elements, Na and Li, in 4000 μg g⁻¹ zirconium dioxide aqueous solution are found to be 0.02 and 0.133 μg g⁻¹, respectively. These values correspond to 5 μg g⁻¹ for Na, 33.25 μg g⁻¹ for Li in original high purity zirconium dioxide powder. The correlation coefficient of calibration curve was 0.995 for Na, 0.985 for Li. Those are comparable to the literature values of detection limits using ICP-OES.     

Effects of various competing ligands on the kinetics of trace metal complexes of Laurentian Fulvic Acid in model solutions and natural waters

The objective of this work was to study the effects of the following Ligands: Chelex-100, Dowex MAC-3 and Dowex 50WX-8 using Competing Ligand Exchange Method. This objective was achieved by investigating complex dissociation kinetics of trace metals: Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Mn(II) and Pb(II) of a well-characterized Laurentian Fulvic Acid (LFA) in model solutions and in a natural waters of Lake Heva (Québec, Canada). The effects of variation in the competing ligands (including their quantities) on the complex dissociation kinetics were quantitatively characterized by their first-order dissociation rate coefficients. The kinetic lability of the metal complexes varied with the metal-to-LFA ratio, as expected from the theory of metal complexes of the chemically and physically heterogeneous complexants, LFA. The general trend in the metal-binding by the above competing ligands was: Dowex 50WX-8 > Chelex-100 > Dowex MAC-3. However, no difference was found between the Dowex 50WX-8 and Chelex-100 for Cd(II), Zn(II), and Co(II). The results revealed the importance of the quantity of Chelex-100 as a competing ligand in the metal(II)-LFA complexation, on the dissociation kinetics of these complexes in model solutions. By developing Competing Ligand Exchange Method as an analytical technique, for studying the relative affinities of the above competing ligands for metals complexation in natural waters this work has made a substantial contribution to analytical chemistry.