原子吸收光谱和原子发射光谱法测定酸雨中钾、钠、钙、镁方法比较

采用原子吸收光谱法和原子发射光谱法分别测定了酸雨中的钾、钠、钙、镁4种元素的含量,并对两种方法的样品前处理技术、标准曲线、方法检出限、准确度、精密度、干扰及消除等进行了比较研究。结果表明,两种方法无显著性差异,均可用于酸雨中钾、钠、钙、镁4种元素的测定。     

对藏族、回族、蒙古族、维吾尔族、哈萨克族和满族人发中7种微量元素的聚类分析

用等离子体发射光谱法对中国藏族、回族、蒙古族、维吾尔族和哈萨克族人发中的钙、镁、铁、锰、铜、锌、镉7种微量元素的含量进行了测定，对满族、蒙古族和维吾尔族3个民族，对藏族、回族、蒙古族、维吾尔族和哈萨克族5个民族进行了聚类分析，两组中每个民族基本上聚为一类，误判率分别小于10％和5％，说明上述民族的头发中7种元素含量的综合水平存在着较显著的差别。     

原子发射光谱法测定炼铜尾气烟灰中砷、锑、铋、钒、铅、碲

应用原子发射光谱法（采用直流电弧激发）测定了炼铜尾气烟尘中砷、锑、铋、铅、碲及钒六元素的含量。对多项工作参数，包括光谱仪的工作条件、分析谱线的选择，与试样混合的缓冲剂之间的质量比等作了试验和优化。按所提出的方法分析了3件试样中的6个元素，各元素的7次测定结果的相对标准偏差在2．8％～23．3％之间。     

酪氨酸在活性炭/水界面上的吸附

研究了不同pH值介质中酪氨酸在活性炭上的吸附行为.结果表明,pH值4.2～6.1时吸附量较大,在酪氨酸的等电点时吸附量最大;酪氨酸被吸附的主要形式是兼性离子;酪氨酸离子靠VanderWaals力吸附在活性炭/水界面上.用介质pH值对酪氨酸溶解度的影响和活性炭的表面性质解释了实验结果     

电感耦合等离子体原子发射光谱测定当归补血汤中铅、铬、镉、砷

采用电感耦合等离子体原子发射光谱测定了当归、黄芪及两种药材不同配伍形式的水煎液中铅、铬、镉、砷等金属元素含量。比较了不同提取方法及磷脂类化合物对当归补血汤中这些金属元素溶出的影响。实验表明,当归、黄芪生药材及水煎液经硝酸消化,样品消解完全,能满足电感耦合等离子体-原子发射光谱(ICP-AES)检测的要求。方法加标回收率为83.0%~96.0%,相对标准偏差为0.36%~4.67%,且当归∶黄芪配比为1∶5时水煎液中重金属元素溶出率低于1∶1配比,证实了当归补血汤经典配方的合理性,为其临床疗效提供了有效依据。     

无公害蔬菜、灌溉水、种植土壤中Pb、As、Cd、Cr的测定

采用原子吸收光谱法测定了广西区内几个无公害生产基地土壤、蔬菜、水样中Pb、As、Cd、Cr的含量,RSD＜7％,回收率在94％－110％之间。用本法测定GBW 08302土壤标准物质,测得值与推荐值基本一致。     

火焰原子吸收光谱法测定芦荟中锰、铁、铜、锌、镍、钴

１　　引　　　　言芦荟作为药用和保健品越来越引起人们的重视。近年来人们将它作为良好的防癌、抗癌药品而食用。芦荟的主要成分为淡黄色结晶性甙,为芦荟大黄素甙,水解产生ｄ－阿拉伯胶糖、芦荟大黄素等。它有良好的抑菌作用,对表皮癣菌、星形奴卡氏菌等皮肤真菌均有不同的抑制作用。主治烧烫伤、肝经实热等症。还能治疗糖尿病、痔疾、中耳炎、减肥等多种疾病。是人们理想的保健品和药品。芦荟中的金属元素的分析,作者未见文献报道。本文用原子吸收光度法测定了３种芦荟中锰、锌、铜、铁、镍、钴的含量,得到了满意的结果。２　　实验…     

电感耦合等离子体原子发射光谱(ICP-AES)法测定内外墙涂料中的钛、钙、锌、镁和硅

采用酸消解,对内外墙涂料中的颜填料进行前处理,建立了电感耦合等离子体原子发射光谱(ICP-AES)法测定内外墙涂料中钛、钙、锌、镁和硅的方法。探讨了在制样及测试过程中的影响因素、方法的检出限和方法的精密度,实验证明精密度(RSD,n=10)小于5%,方法准确度高,方法能满足内外墙涂料快速检测的要求。     

原子吸收光谱法同时测定颜料中铜、铁、铅、镉含量

酞青颜料是由4个异吲哚单元组成的平面大环共轭配合物,其中心原子一般为二价金属离子。其中酞青蓝(铜酞青)应用最广泛,具有良好的光、热、电性质及化学稳定性,不仅可作蓝色、绿色颜料原料,还可用于电子半导体。酞青蓝颜料中铜的含量范围为0.50%～5.00%,是影响其颜色和导电性的主要因素,同时还含有少量的铁、钙、镁及微量重金     

电感耦合等离子体原子发射光谱法测定钼铜合金中镍、钙、镁、铝含量

钼铜合金是综合了钼和铜两种材料特性的一种合金,近年来被广泛应用于铁路、真空电子、航空、航天、军工等领域。对钼铜合金中化学成分有效准确的分析成为其质量保证的重要依据。钼铜合金中镍、钙、镁、铝元素分析通常采用分光光度法或原子吸收光谱法,存在每个元素对应一种方法、操作比较繁琐的缺点。本工作提出了电感耦合等离子体     

Theoretical studies on the ionization potential of interacting atoms at large separations

The theory of the one-particle Green's function is applied to calculations of the ionization potential of interacting atoms which are at large separations. Equations for the ionization potential involve terms which relate to Van der Waals interactions between separated atoms and long-range interactions between an atom and an ion. Numerical calculations of the ionization potential of two hydrogen atoms and two helium atoms at large separations are performed. Applications to the ionization potentials of weakly-interacting Van der Waals molecules (NeAr, NeKr, NeXe) are also reported.     

水介质中氢键吸附与疏水吸附协同作用的研究

研究了丙烯酸型树脂(D152)在水、乙醇和正己烷中对苯胺、N-甲基苯胺和N,N-二甲基苯胺的吸附行为.在水中D152树脂对3种吸附质的吸附亲合性随N上甲基数的增加而增大,说明疏水作用是主要的吸附机理,但其吸附焓己超出范德华力的范围而在氢键的键能范围内,故氢键吸附也同时在起作用.在正己烷中,D152树脂对3种吸附质的吸附亲合性随N上甲基数的增加而减小,与水中呈相反的趋势,说明氢键作用是主要的吸附机理.在乙醇中,D152树脂对3种吸附质均无吸附,因为疏水作用和氢键作用均受到的乙醇抑制.在水中,吸附质与树脂间的氢键作用同样受到水的抑制,但氢键吸附却依然存在,说明水介质中氢键吸附和疏水吸附可能存在一种协同作用.在热力学上对水介质中氢键吸附和疏水吸附的协同作用给于合理的解释.     

EFFECT OF WEAK INTERACTIONS ON PHENOL ADSORPTION FROM AQUEOUS SOLUTIONS BY AMINATED POLYMERIC ADSORBENTS

Adsorption behaviors of phenol from aqueous solutions have been investigated in batch systems at 303 K and 318 K respectively, using hypercrosslinked polymeric adsorbent （CHA111）, aminated hypercrosslinked polymeric adsorbents （NDA101, NDA103, NDA105） and weakly basic polymeric adsorbent （D301） with a view to studying the effect of hydrogen bonding and Van der Waals interactions between adsorbate and the adsorbent. All adsorption isotherms can be well fitted by Langmuir and Freundlich equations. Compared with D301 driven by hydrogen bonding interaction only and CHA111 driven by Van der Waals interaction only, phenol adsorption on aminated adsorbents driven by both hydrogen bonding and Van der Waals interactions were apparently different, i.e., negative effect for NDA105, positive effect for NDA101 and synergistic effect for NDA103. In this synergistic action, some weak interactions would contribute more or less to the adsorption than they work individually.     

Solvent shift of the ionization potential of the aniline-argon system

The resonant two-photon two-color ionization technique has been used to ionize the Aniline molecule and its Van der Waals complexes with rare gases formed in a supersonic free jet. By scanning the ionizing photon energy, ionization threshold have been determined for Aniline and its first two Van der Waals complexes with Argon. The Ar₁ complex has an ionization energy 96 cm^?1 lower than bare Aniline and the Ar₂ complex has an ionization energy 98 cm^?1 lower than the Ar₁ complex (194 cm^?1 lower than bare Aniline). An interesting correlation has been found between the first Ar-complex solvent shift of the IP for a series of aromatic-argon Van der Waals complexes and the IP of the bare molecule. A simple theoretical model is proposed to discuss the observed correlation.     

取代芳烃水中溶解度的测定与估算

本文应用线性溶剂化能相关法回归分析了多种有机有机物的溶解度与范德华体积、Ｌｅｗｉｓ酸性及Ｌｅｗｉｓ碱性之间的相关性，结果表明，溶解度与范德华体积、Ｌｅｗｉｓ酸性及碱性之间呈良好的相关性，用这种方法估算的溶解度值与测定吻合得较好。     

Van der Waals Radii of Hydrogen in Gas-Phase and Condensed Molecules

Van der Waalsa radii of hydrogen in the different gas-phase and condensed molecules are determined and shown that a value of the van der Waals radius depends on the effective charge of the H atom. Is described also the van der Waals anisotropy of H in some molecules.     

The application of molecular modelling to the interpretation of inverse gas chromatography data

The use of molecular modelling in the interpretation of inverse gas chromatography data is discussed. Crystal faces can be visualised and likely cleavage planes calculated using the surface attachment energies. Assuming that the preferred cleavage plane is the crystal face with the smallest attachment energy then the predominant crystal faces of a crystalline particle can be predicted. Surface adsorption can be modelled using Van der Waals and electrostatic interactions to evaluate the interaction energies between individual atoms of the probe molecule and atoms of the test molecule orientated as in the surface. Using examples of pharmaceutical materials, modelling has been shown to be successful in the understanding of changes in the surface energetics.     

Crystal and molecular structure of pyridazine-3-carboxylic acid hydrochloride and zinc(II) pyridazine-3-carboxylate tetrahydrate

Crystals of pyridazine-3-carboxylic acid hydrochloride contain almost planar molecular sheets in which the cations, composed of acid molecules each with a hydrogen atom attached to one of the ring-nitrogen atoms, interact with chloride anions via a network of weak hydrogen bonds. Van der Waals interactions between sheets are indicated by the intersheet spacing of 3.47?Å. The crystal structure of di(aqua-O)bis(trans-pyridazine-3-carboxylato-N,O)zinc(II) dihydrate is composed of monomeric molecules in which the zinc(II) ion at the center of symmetry is coordinated by two ligand molecules each via its N,O bonding moiety. The ligand molecules and the metal ion form a trans-planar configuration. Two water oxygen atoms, above and below the plane, complete a distorted octahedron. A network of weak hydrogen bonds holds the monomers together.     

Hydrogen-hydrogen bonding: a stabilizing interaction in molecules and crystals

Bond paths linking two bonded hydrogen atoms that bear identical or similar charges are found between the ortho-hydrogen atoms in planar biphenyl, between the hydrogen atoms bonded to the C1-C4 carbon atoms in phenanthrene and other angular polybenzenoids, and between the methyl hydrogen atoms in the cyclobutadiene, tetrahedrane and indacene molecules corseted with tertiary-tetra-butyl groups. It is shown that each such H-H interaction, rather than denoting the presence of "nonbonded steric repulsions", makes a stabilizing contribution of up to 10 kcal mol(-1) to the energy of the molecule in which it occurs. The quantum theory of atoms in molecules-the physics of an open system-demonstrates that while the approach of two bonded hydrogen atoms to a separation less than the sum of their van der Waals radii does result in an increase in the repulsive contributions to their energies, these changes are dominated by an increase in the magnitude of the attractive interaction of the protons with the electron density distribution, and the net result is a stabilizing change in the energy. The surface virial that determines the contribution to the total energy decrease resulting from the formation of the H-H interatomic surface is shown to account for the resulting stability. It is pointed out that H-H interactions must be ubiquitous, their stabilization energies contributing to the sublimation energies of hydrocarbon molecular crystals, as well as solid hydrogen. H-H bonding is shown to be distinct from "dihydrogen bonding", a form of hydrogen bonding with a hydridic hydrogen in the role of the base atom.     

Anisotropy of the van der Waals Configuration of Atoms in Complex,Condensed, and Gas-Phase Molecules

Anisotropic van der Waals (vdW) radii of 5b–7bsubgroup elements were determined from structures of gas-phase van der Waals complexes and crystal molecular compounds. The anisotropy of the van der Waals configuration of atoms was shown to decrease when going from isolated molecules to the condensed state. Variations in intermolecular distances, which are usually explained in terms of the formation of hydrogen bonds, are substantially governed by the anisotropic effect.