氢化物发生电感耦合等离子体原子发射光谱法同时测定水和生物样品中…

研究了一种小型同心氢化物发生配置一个气液分离器后与多道ＩＣＰ－ＡＥＳ联用，同时测定水和生物样品中砷、铋、锑、硒的方法。检出限为砷０．４μｇ／Ｌ，铋０．５μｇ／Ｌ，锑１．４μｇ／Ｌ，硒０．５μｇ／Ｌ，相对标准偏差为砷２．７％，铋１．５％，锑２．７％，硒１．９％。用本法测定美国和国家标准物质中的氢化元素，结果满意。     

氢化物发生-原子荧光光谱法测定海洋沉积物中砷、锑、铋、汞、硒

提出了用盐酸-硝酸-水(3+1+4)混合酸消解样品,氢化物发生-原子荧光光谱法测定海洋沉积物样品中砷、锑、铋、汞、硒的方法。考察了原子荧光光谱仪的最佳工作条件。在最佳条件下砷、锑、铋、硒的检出限(3s/k)分别为0.018,0.004,0.001,0.003μg.g-1,汞的检出限(3s/k)为0.604ng.g-1。应用于3种海洋沉积物标准物质的测定,测定值与标准值吻合。     

高压釜消解-氢化物发生原子荧光光度法测定土壤中的砷、硒

对高压釜密封消解一氢化物发生原子荧光法测定土壤中砷、硒的方法进行了研究。采用HNO3-HClO4作消解剂，在最佳的消解条件和测定条件下，测定砷、硒的线性回归方程分别为I=244．1c 1．03、I=88．26c 2．86．线性范围均为0．50～10．00μg／L，相关系数均为0．9999，检出限均为0．0002μg/mL。测定土壤中砷、硒的回收率分别为90％～105％、89％～104％，RSD分别为2．2％～4．0％、1．9％～3．1％。     

氢化物发生-原子荧光光谱法同时测定水中砷和锑

建立在硝酸介质中用氢化物发生-原子荧光光谱法同时测定水中砷和锑的方法。优化了仪器工作条件、酸度、硼氢化钾及还原剂浓度。砷、锑的线性范围为0～10．0μg／L;检出限分别为0．02,0．01μg／L;测定结果的相对标准偏差分别为1．77％～3．72％,2．95％～4．87％（n=6）;加标回收率分别为98％106％,96％105％。该法操作简便,灵敏度高,快速,便于推广,适用于水中砷和锑的同时测定。     

氢化物原子荧光光谱法测定水中微量砷和硒

研究了氢化物发生-原子荧光光度法测定水中微量砷和硒的方法。结果表明,检出限:砷为0.0518μg/L,硒为0.0524μg/L;11次测定的相对标准偏差为0.36％～0.62％;标准回收率:砷为96.8％～100.9％;硒为95.9％～103.7％。方法简便、快速、灵敏,适于生活饮用水、地表水和水源水中微量砷、硒的同时测定。     

碱熔-氢化物发生原子荧光光谱法连续测定锑精矿中的砷、铋、硒、锡

建立了氢化物发生原子荧光光谱法测定锑精矿中砷、铋、硒、锡的方法.研究了基体及共存元素的干扰情况,实验表明,在酒石酸、硫脲-抗坏血酸存在下,适当的增加酸度可以有效地消除干扰.采用Na2O2熔解样品,用HCl酸化,无需分离基体,实现了锑精矿中砷、铋、硒、锡的连续测定,其回收率为90.6%～103.8%,检出限分别为0.35、0.20、0.65和0.35 μg/L.应用该方法分析了锑精矿样品,结果令人满意.     

氢化物-原子荧光法同时测定大米中的砷和硒

采用氢化物-原子荧光光谱法测定大米中的砷和硒。在0～10μg／L范围内,砷和硒的浓度与荧光强度呈线性关系,相关系数分别为0．9996和0．9998,加标回收率分别为96．2％～100．8％和98．1％～107．6％,砷、硒测定结果的相对标准偏差分别不大于6．8％,5．7％（n=6）。     

萃取-缝式石墨管原子捕集火焰原子吸收法测定水样中痕量锑(Ⅲ)和锑(Ⅴ)

研究了锑(Ⅲ)和锑(Ⅴ)在DDTC—MIBK体系中的萃取和反萃取行为，用缝式石墨管原子捕集技术结合火焰原子吸收法测定了水样中的痕量锑(Ⅲ)和锑(Ⅴ)，线性范围为2．0—60μg／L，检出限为0．4μg／L，特征浓度为1．5μg/L／1％吸收，相对标准偏差为2．6％，锑回收率为93．0％一105．0％。     

氢化物原子荧光光谱法测定虾中砷和汞

建立了氢化物原子荧光法同时测定虾中砷和汞的方法。研究了样品前处理及实验条件对测定砷、汞的原子荧光强度的影响，并探讨了共存离子对测定砷、汞的干扰和消除的方法。本方法具有操作简便、快速、灵敏度高等优点，砷和汞的检出限分别为0．026μg/L和0．020μg／L；相对标准偏差分别为1．7％～9．4％和1．2％～9．4％；回收率为98％～106％。     

电感耦合等离子体发射光谱法测定粗二氧化碲中 铜、铅、锑、铋、砷和硒

粗二氧化碲作为碲精炼或碲化工产品生产的重要原料,其中共存元素铜、铅、砷、锑、铋、硒含量的准确测定对于生产过程质量控制和贸易结算具有重要意义,但目前没有粗二氧化碲中铜、铅、砷、锑、铋、硒含量检测的标准分析方法。采用王水和饱和氟化氢铵分解试样,在王水和酒石酸介质中,选用Cu 327.393 nm、Pb 220.353 nm、Sb 217.582 nm、Bi 223.061 nm、As 193.696 nm、Se 196.026 nm为分析谱线,采用电感耦合等离子体发射光谱(ICP-AES)法测定粗二氧化碲中铜、铅、锑、铋、砷和硒含量。各元素校准曲线的相关系数均大于0.999;铜、铅、锑、铋、砷和硒的检出限分别为0.0004%、0.0005%、0.0006%、0.0007%、0.0004%和0.0007%,定量检出限分别为0.0012%、0.0016%、0.0020%、0.0025%、0.0013%和0.0025%。按照实验方法测定5个粗二氧化碲样品中铜、铅、锑、铋、砷和硒,测定结果的相对标准偏差(RSD,n=7)为0.79%~4.8%,加标回收率为96.0%~103%。方法简单,精密度和准确度较高,可用于测定粗二氧化碲中铜、铅、砷、锑、铋、硒含量。     

Organogermyl,Organostannyl, and Organoplumbyl Phosphines,Arsines, Stibines,and Bismuthines

The preparation, properties, and reactions of the compounds named in the title are described, with particular reference to the possible participation of (p→d)_π components in the bonding between the group IVB and the group VB elements.     

Pyrenes,Peropyrenes, and Teropyrenes: Synthesis,Structures, and Photophysical Properties

The design of a relatively simple and efficient method to extend the π‐conjugation of readily available aromatics in one‐dimension is of significant value. In this paper, pyrenes, peropyrenes, and teropyrenes were synthesized through a double or quadruple benzannulation reaction of alkynes promoted by Brønsted acid. This novel method does not involve cyclodehydrogenation (oxidative aryl–aryl coupling) to arrive at the newly incorporated large arene moieties. All of the target compounds were synthesized in moderate to good yields and were fully characterized with the structures unambiguously confirmed by X‐ray crystallography. As expected, photophysical characterization clearly shows increasing red‐shifts as a function of extended conjugation within the fused ring systems.     

Pyrenes,Peropyrenes, and Teropyrenes: Synthesis,Structures, and Photophysical Properties

The design of a relatively simple and efficient method to extend the π‐conjugation of readily available aromatics in one‐dimension is of significant value. In this paper, pyrenes, peropyrenes, and teropyrenes were synthesized through a double or quadruple benzannulation reaction of alkynes promoted by Brønsted acid. This novel method does not involve cyclodehydrogenation (oxidative aryl–aryl coupling) to arrive at the newly incorporated large arene moieties. All of the target compounds were synthesized in moderate to good yields and were fully characterized with the structures unambiguously confirmed by X‐ray crystallography. As expected, photophysical characterization clearly shows increasing red‐shifts as a function of extended conjugation within the fused ring systems.     

Structural, magnetic, and spectroscopic studies of YAgSn, TmAgSn, and LuAgSn

The rare earth-silver-stannides YAgSn, TmAgSn, and LuAgSn were synthesized from the elements by arc-melting and subsequent annealing. The three stannides were investigated by X-ray powder and single-crystal diffraction: NdPtSb type, P6₃mc, Z=2, a=468.3(1), pm, wR₂=0.0343, 353 F² values, 12 variables for YAgSn, and ZrNiAl type, P6¯2 m, a=726.4(2), , wR₂=0.0399, 659 F² values, 15 variables for TmAgSn, and a=723.8(2), , wR₂=0.0674, 364 F² values, 15 variables for LuAgSn. Besides conventional laboratory X-ray data with monochromatized Mo radiation, the structures were also refined on the basis of synchrotron data with , in order to clarify the silver-tin ordering more precisely. YAgSn has puckered, two-dimensional [AgSn] networks with Ag-Sn distances of 278 pm, while the [AgSn] networks of TmAgSn and LuAgSn are three-dimensional with Ag-Sn distances of 279 and 284 pm for LuAgSn. Susceptibility measurements indicate Pauli paramagnetism for YAgSn and LuAgSn. TmAgSn is a Curie-Weiss paramagnet with an experimental magnetic moment of 7.2 μ_B/Tm. No magnetic ordering is evident down to 2 K. The local environments of the tin sites in these compounds were characterized by ¹¹⁹Sn Mössbauer spectroscopy and solid-state NMR (in YAgSn and LuAgSn), confirming the tin site multiplicities proposed from the structure solutions and the absence of Sn/Ag site disordering. Mössbauer quadrupolar splittings were found in good agreement with calculated electric field gradients predicted quantum chemically by the WIEN2k code. Furthermore, an excellent correlation was found between experimental ¹¹⁹Sn nuclear magnetic shielding anisotropies (determined via MAS-NMR) and calculated electric field gradients. Electronic structure calculations predict metallic properties with strong Ag-Sn bonds and also significant Ag-Ag bonding in LuAgSn.     

Borinium, borenium, and boronium ions: synthesis, reactivity, and applications

Boron cations are elusive and highly electrophilic species that play a key role in the chemistry of boron. Despite early interest in the chemistry of boron cations, until recently they have largely remained chemical curiosities. However, hints at harnessing their potential as potent electrophiles have begun to appear and developments in weakly coordinating anion technology suggest that this is an area of research that is ripe for exploration. It has been nearly 20 years since the last major review on boron cations; herein we summarize the progress in the area since that time.     

Pi bonding and negative hyperconjugation in mono-, di-, and triaminoborane, -alane, -gallane, and -indane

A systematic quantum chemical investigation of mono-, di-, and triaminoborane, -alane, -gallane, and -indane is carried out to determine quantitatively the effects of pi bonding and negative hyperconjugation on structures, energetics, and rotational barriers in these systems. Pi bonding plays a significant role in the aminoborane compounds, but becomes rapidly less significant in the aminoalanes, -gallanes, and -indanes. For each main-group metal X investigated, X-N rotational barriers are found to be essentially equal depending only on the number of remaining in-plane amino groups. The contribution of negative hyperconjugation to reducing rotational barriers, as assessed from natural bond orbital (NBO) delocalization energies, is independent of the pyramidalization of the out-of-plane amino group, and is also dependent only on the number of rotated groups. Optimized tris[bis(trimethylsilyl)amino]-substituted structures of boron, aluminum, gallium, and indium are found to compare quite well with available experimental structural data, and exhibit X-N torsion angles that are independent of the central metal atom.     

Transition-metal-free O-, S-, and N-arylation of alcohols, thiols, amides, amines, and related heterocycles

A new protocol for the Ullmann-type arylation process of different aromatic heterocycles without any transition-metal catalyst, implying the use of a combination of an excess of potassium hydroxide and dimethyl sulfoxide, is described. The reaction can be performed between a broad range of starting nucleophiles including phenol, alcohols, amines, nitrogen-containing five-membered systems such as pyrazoles, imidazoles, and indoles, and amides with haloarenes, iodide and bromide derivatives giving the best results, the possible pathway involving the in situ generation of the corresponding benzyne intermediate. When the reaction was performed with 2-iodoaniline and either carboxamides or isothiocyanato derivatives, the corresponding benzoazole derivatives were obtained.     

铬,硒,镉,锰与心脑血管疾病

通过对５０例心脑血管疾病病人及５０例健康对照组血中微量元素铬、硒、镉、锰的检测分析证实，心脑血管疾病病人血清Ｃｒ、Ｓｅ含量下降，Ｃｄ含量未见明显升高，并进一步探讨了这些微量元素与心脑血管疾病的发生发展的关系及其临床意义。     

Rare-Earth-compound nanowires, nanotubes, and fullerene-like nanoparticles: synthesis, characterization, and properties

Various low-dimensional nanostructures, such as nanowires, nanotubes, nanosheets, and fullerene-like nanoparticles have been selectively synthesized from rare-earth compounds (hydroxides, fluorides) based on a facile hydrothermal method. The subsequent dehydration, sulfidation, and fluoridation processes lead to the formation of rare-earth oxide, oxysulfide, and oxyhalide nanostructures, which can be functionalized further by doping with other rare-earth ions or by coating with metal nanoparticles. Owing to the interesting combination of novel nanostructures and functional compounds, these nanostructures can be expected to bring new opportunities in the vast research areas of and application in biology, catalysts, and optoelectronic devices.