ICP-AES法测定玩具涂料中重金属元素总量

研究了不同消解方法对玩具涂料中As,Ba,Cd,Cr,Hg,Pb,Sb,Se有害重金属元素总含量测定结果的影响，确定以HNO3＋酒石酸＋H3PO4溶样并用全谱直读等离子体光谱仪同时测定其八种有害重金属元素总含量的方法。加标回收试验及模拟样品测定结果表明，该方法快速、准确、可靠，且能满足玩具安全标准对各元素的检出限要求，适于进出口玩具的日常检验。     

顺序注射氢化物发生-原子荧光光谱法测定化肥中砷、汞、锑和硒

本文建立了一种顺序注射氢化物发生 -原子荧光光谱法测定化肥中 As、Hg、Sb、Se含量的方法。在最佳条件下 ,As、Hg、Sb和 Se的检出限分别为 0 .1 5μg/ L、0 .0 6 1μg/ L、0 .0 4 6μg/ L、0 .2 5μg/ L。测定化肥中 As、Hg、Sb和 Se,回收率均在 94 .6 7%— 1 0 6 .81 %之间。该方法用于检测化肥中 As、Hg、Sb和 Se具有很好的可行性和实用性。     

开放式微波消化-ICP-MS法快速测定食品中多种微量元素

开放式微波消解系统消化食品样品 ,以 45Sc、89Y、1 1 5In、2 0 9Bi作内标元素抑制分析信号的动态漂移 ,加入 1 %异丙醇消除 C元素对 As、Se等元素的干扰 ,建立食品中多种元素同时测定的ICP- MS方法。对 4类食品 (奶粉、鹅肝酱、水果片、燕麦片 )中的 1 2种元素 (Al、Cr、Ni、Ge、As、Se、Ag、Cd、Sn、Sb、Pb、Hg)进行了直接测定 ,绝大部分回收率在 85 %— 1 1 0 %之间 ;线性相关系数均大于 0 .999;精密度 (RSD)值 <1 0 %。对国家标准物质 (SRM)进行了分析 ,测得值与标准参考值相吻合。该法灵敏度、精密度和准确度都能满足有关标准的要求 ,具有多元素同时分析、样品前处理简单、干扰少、测定快速准确 ,省事省力等优点。     

氢化物发生-电感耦合等离子体原子发射光谱法同时测定人发中氢化元素和非氢化元素

采用连续氢化物发生法,在酸性介质中,对人发样品中可形成氢化物的元素（As,Se,Pb,Hg,Sb)和棵氢化元素（Zn,Cr,Mg,Mn,Ca,Fe,Cu,Ni,Cd,Al,Co,Mo,Ba)进行同时测定。研究了酸度、NaBH4的浓度、载气流速、清洗时间对氢化元素的影响,比较了传统雾法和（雾化＋氢化法）对氢化元素和非氢化元素的影响,选择了最佳分析条件。对标准人发样品中的18种元素进行了测定,结果令人满意。     

原子荧光法测定刺五加不同部位中的砷、锑、汞、硒

采用微波消解处理样品,建立了氢化物发生-原子荧光法测定刺五加不同部位中的As, Sb, Hg, Se的分析方法。在最佳工作条件下,Se, Sb, Hg, Se的浓度与荧光强度均呈现良好的线性关系。砷的检出限为0.068 ng·mL-1,RSD为1.05%;锑的检出限为0.155 ng·mL-1,RSD为1.32%;汞的检出限为0.014 ng·mL-1,RSD为2.03%;硒的检出限为0.052 ng·mL-1,RSD为2.34%。并选用标准物质人发(GBW07601)对测定方法的准确度进行考察,该方法灵敏、快速准确。实验结果表明,刺五加不同部位中As, Sb, Hg, Se的含量有所差异。As, Hg和Se主要在叶中含量较高,锑在根中的含量高于其他部位。     

氢化物发生—原子荧光法测定不同产地绞股蓝及其根际土壤中As,Hg,Se

通过优化了的氢化物发生—原子荧光法测定了7个省产绞股蓝及其根际土壤中As,Hg,Se三种元素的含量,研究结果表明:7个省产绞股蓝中As,Hg,Se的含量存在较大差异,但As和Hg两种重金属元素含量均低于《药用植物及制剂进出口绿色行业标准》中As和Hg的限量标准。Se元素含量同根际土壤中Se元素含量显示极显著相关性,故湖北恩施富硒区产绞股蓝中Se含量明显高于其他6省产绞股蓝。研究结果可以初步判定,绞股蓝中Se元素主要来源于土壤,而As和Hg元素的积累则不同于Se元素,还可能受到大气气溶胶的干、湿沉降等因素的影响。     

连续氢化法电感耦合等离子体发射光谱同时测定生物样品中痕量硒、砷、锡、锑

本文叙述用氢化法电感耦合等离子体发射光谱同时测定生物样品中痕量硒、砷、锡、锑的方法。比较了浓度为2.88mol/L,4.8mol/L和6.0mol/L的HCl对Se,As,Sn,Sb,Hg和Ge谱线强度的影响,也比较了NaBH_4溶液中VC对测定Se,As,Sb,Sn,Hg和Ge的影响。在4.8mol/L HCl浓度下,在1％NaBH_4溶液中加0.5％VC,HY-ICP-AES的检出限是:Se 0.3ng/ml,As 2.5ng/ml,Sn 5.0ng/ml,sb 0.4ng/ml,Hg 0.3ng/ml,Ge 8.0ng/ml。用国家标准物质GBW09101来检验本方法的准确性,得到的se,As,Sn和Sb结果良好。     

原子荧光光谱法测定不同产地茶叶中As，Se，Hg和Bi四种元素含量

收集了21种中国茶叶和五种日本茶叶,经过微波或湿法消解后,采用原子荧光光谱法(AFS)测定了As, Se, Hg和Bi四种元素的含量,并用植物标准参考物质评价了分析方法的准确度。另外,还探讨了As, Se, Hg和Bi在幼龄茶树不同部 位的含量分布特征。研究结果表明：微波消解对于获得较为准确的茶叶中Hg含量分析结果必不可少;与日本茶叶相比,中国茶叶中As, Se, Hg和Bi元素含量显著偏高,但君山银针中Bi含量最低;As, Se和Hg主要积累于幼龄茶树的树皮、根 系、老叶等部位,而Bi在幼龄茶树根系、去皮树干中含量则低于AFS检测限。从本次研究结果可以初步断定,茶树并非是一种Se积累植物,中国茶叶中人体必需微量元素Se主要来源于大气气溶胶的干、湿沉降。     

APDC-MIBK萃取石墨炉原子吸收光谱法测定As(Ⅲ、Ⅴ)、Se(Ⅲ、Ⅵ)和Sb(Ⅲ、Ⅴ)

环境和生物样品中As、Se和Sb的测定具有重要意义。它们的毒性和生理行为与其价态有密切关系。Kamada和Yamamoto等分别以石墨炉和氢化物发生法对上述元素的不同价态进行了报导。Subramanian在柠檬酸铵缓冲溶液及HCl介质中,以硫氰酸盐还原可选择测定不同价态。Chanhuan Chung在醋酸缓冲溶液中,以TiCl_3还原可以区分高、低价态,用CHCl_3和CCl_4混合溶剂萃取,选择测定As、Se、     

微波消解-ICP-OES,AAS和AFS测定大蒜不同部位20种元素含量

将大蒜植株分为根、茎(下)、茎(中)、茎(上)、嫩叶和老叶6个不同部位,采用微波消解方法对各个部位进行了预处理,并用电感耦合等离子体发射光谱法(ICP-OES)、原子吸收光谱法(AAS)和原子荧光光谱法(AFS)测定了其中Al,As,B,Ca,Cd,Cr,Cu,Fe,Hg,K,Mg,Mn,Na,Ni,P,Pb,S,Se,Sr和Zn共20种元素的含量,另外,还测定了从同一处土壤中采收的大蒜头中相应元素的含量.研究结果表明:大蒜植株嫩叶和大蒜头中Cu,Fe,Mn,S,Se,Zn等元素含量较高而As,Cd,Hg,Pb等元素含量较低,是提取大蒜生物活性物质的绝好材料;一些元素在大蒜植株不同部位的含量分布模式能高度反映植物生理特性或环境污染状况.     

Morphologically different WO3 nanocrystals in photoelectrochemical water oxidation

Different morphologies of WO₃ nanocrystals such as nanorods and nanoplates have been obtained under hydrothermal conditions using ammonium metatungstate as the precursor in presence of different organic acids such as citric, oxalic, and tartaric acid in the reaction medium. Detailed characterization of the crystal structure, particle morphology, and optical band gap of the synthesized powders have been done by X-ray diffraction, transmission electron microscopy, scanning electron microscopy and solid-state UV–visible spectroscopy study. The as-synthesized materials are WO₃ hydrates with orthorhombic phase which transform to the hexagonal WO₃ through dehydration upon heating at 350 °C. The resultant products are crystalline with nanoscale dimensions. Finally, the photoactivity of the synthesized materials annealed at 500 °C has been compared employing in photoelectrochemical water oxidation under the illumination of AM 1.5G simulated solar light (100 mWcm⁻²). The photocurrent measurements upon irradiation of light exhibit obvious photocatalytic activity with a photocurrent of about 0.77, 0.61, and 0.65 mAcm⁻² for the WO₃ film derived with the oxalic acid, tartaric, and citric acid assisting agents, respectively, at 1.8 V versus Ag/AgCl electrode.     

利用红外光谱分析有机羧酸在均相反应中的配位作用机理

利用红外(IR)光谱、X射线衍射(XRD)及透射电子显微镜(TEM)等手段,对有机羧酸在尿素及硝酸铈的均相反应混合溶液中所起的配位作用进行了分析,并对产品的物相和形貌进行了测试与表征。实验结果表明：在尿素及硝酸铈的混合溶液中分别加入一元羧酸硬脂酸,二元羧酸酒石酸和三元羧酸柠檬酸时,一元羧酸硬脂酸在混合溶液中只起表面活性剂的作用,其产物为斜方晶系的单晶Ce₂O(CO₃)₂·H₂O微粉,且表面活性剂硬脂酸的加入使得晶体的晶化程度明显提高;而二元羧酸酒石酸与三元羧酸柠檬酸在均相反应中则起螯合剂的作用,分别与Ce3+形成螯合物酒石酸铈和柠檬酸铈,这些结果的造成是由于其反应机理的不同所导致的。     

Ultrasonic degradation of oxalic acid in aqueous solutions

This paper describes the ultrasonic degradation of oxalic acid. The effects of ultrasonic power, H₂O₂, NaCl, external gases on the degradation of oxalic acid were investigated. Reactor flask containing oxalic acid was immersed in the ultrasonic bath with water as the coupling fluid. Representative samples withdrawn were analysed by volumetric titration. Degradation degree of oxalic acid increased with increasing ultrasonic power. It was observed that H₂O₂ has negative contribution on the degradation of oxalic acid and there was an optimum concentration of NaCl for enhancing the degradation degree of oxalic acid. Although bubbling nitrogen gave higher degradation than that for bubbling air, both gases (for 20 min before sonication and during sonication together) could not help to enhance the degradation of oxalic acid when compared with the degradation without gas passage.     

Effects of Chemical Heat Sink Generated by an Oxalic Acid Cooling Stream on Film-Cooling Effectiveness

Based on the theory of heat transfer enhancement, a novel film-cooling method for turbine blades that involves a chemical heat sink generated by the use of oxalic acid as a cooling stream has been proposed. Experiments were conducted on a flat plate with a row of 30° angled holes, and the conventional method using air as the cooling stream was examined for comparison. Overall, the results of this study demonstrate that the proposed cooling method involving an oxalic acid-induced chemical heat sink is more effective than the conventional method.     

Tracer studies of anodic films formed on aluminium in malonic and oxalic acids

Using a tungsten-containing layer, incorporated into sputtering-deposited aluminium, as a tracer, the growth of porous anodic films in malonic and oxalic acid electrolytes has been investigated using transmission electron microscopy, Rutherford backscattering spectroscopy and nuclear reaction analysis. Comparisons were also made with films formed in phosphoric acid electrolyte, which have been studied previously. The findings reveal a distortion of the tracer layer within the barrier region of the porous films, evident as a lagging of the tracer beneath the pores relative to that in the adjacent cell wall region. Further, the films are significantly thicker than the layer of metal consumed during anodizing and display smooth-sided pores. The anodizing behaviours are consistent with a major role for field-assisted flow of film material within the barrier layer in the development of the pores.     

Structure and magnetic properties of nanocrystalline cobalt ferrite powders synthesized using organic acid precursor method

Nanocrystalline octahedra of cobalt ferrite CoFe₂O₄ powders were synthesized using the organic acid precursor route. The effect of the calcination temperature, Fe³⁺/Co²⁺ molar ratio, calcination time and type of organic acid (oxalic, benzoic and tartaric acids) on the formation, crystallite size, microstructure and magnetic properties was studied systematically. The Fe³⁺/Co²⁺ molar ratio was varied from 2 to 1.739 while the annealing temperature was controlled from 400 to 1000 °C for various periods from 0.5 to 2 h. The resulting powders were investigated using X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). XRD results indicate that a well crystallized, single spinel cobalt ferrite phase was formed for the precursors annealed at 600-800 °C for 2 h, using oxalic and tartaric acids as precursors for Fe³⁺/Co²⁺ molar ratio 1.818. The crystallite size of as-formed powders was in the range of 38.0-92.6 nm at different operating conditions. The calcination temperature and Fe³⁺/Co²⁺ molar ratio have a significant effect on the microstructure of the produced cobalt ferrite. The microstructure of the produced powders was found to be octahedra-shaped. The crystalline, pure cobalt ferrite powders with magnetic properties having a maximum saturation magnetization (76.1 emu/g) was achieved for the single phase at Fe³⁺/Co²⁺ molar ratio 1.818 and annealing temperature of 600 °C for 2 h using tartaric acid precursor.     

石墨炉原子吸收光谱中有机基体改进剂消除海水基体干扰的研究

本文采用Ｄ２灯扣除背景、管壁原子化、热解涂层石墨管和积分吸收信号，研究了以酒石酸、抗坏血酸和柠檬酸等有机基体改进剂消除海水基体对测定Ｃｄ、Ｃｏ、Ｃｒ、Ｃｕ、Ｍｎ、Ｍｏ、Ｎｉ和Ｐｂ等元素干扰的效果，探讨了有机基体改进剂的作用机理，分析测定了海水样品中的痕量元素。     

DFT study of the hydrogen bond strength and IR spectra of formic,oxalic, glyoxylic and pyruvic acids in vacuum,acetone and water solution

The molecular geometries of the possible conformations of formic, oxalic, glyoxylic and pyruvic acids have been fully optimized at DFT B3LYP/6‐311++G(d,p) levels of calculation in vacuum as well as in water and acetone solution. Solutions were treated according to the SCRF PCM approach but some formic acid–water and formic acid–acetone clusters as well as adducts of oxalic acid with two or four water molecules were also taken into account for testing the importance of specific solute–solvent effects. All the most stable isomers of the title compounds are characterized by weak intramolecular hydrogen bonds, whose strengths (E_HB) cannot be correctly estimated as stability difference between the open and chelate forms since the energy of the former isomer is, in turn, stabilized by a weak hydrogen bridge due to the formic acid moiety. Following the Rotation Barrier Method (RBM), proposed some years ago, E_HB in the examined molecules (gas phase) falls in the range of 18–22 kJ/mol for oxalic acid (9.6 kJ/mol for the c‐C‐t isomer), 16.8 kJ/mol for glyoxylic acid and 19.8 kJ/mol for pyruvic acid. Most of them disappear at all, or nearly at all, both in acetone and aqueous solution, in consequence of the solvent effect. The frequencies of the OH and C?O stretching modes, calculated according to the anharmonic oscillator model, are in very good agreement with the experimental literature data, where available. Copyright © 2009 John Wiley & Sons, Ltd.     

Studies of Atmospherically Relevant Reactions Using Differentially Pumped Mass Spectrometer and Fourier Transform Infrared Spectroscopy

This article describes recent studies of atmospherically relevant reactions using spectroscopic techniques by our group at the Wadsworth Center. Heterogeneous reactions of SO₂ with either HOBr or HOCl on ice have been studied using a coated-wall flow reactor coupled with differentially pumped quadrupole mass spectrometer, and the reaction of NO₂+HI has been investigated using Fourier transform infrared spectroscopy (FTIR). Reaction probabilities or rate constants have been determined at relevant atmospheric temperatures. Specular reflection-absorption infrared spectroscopy and the temperature programmed desorption technique were employed to study the adsorption of oxalic acid on a Cu surface at 175 K. Reflection-absorption infrared spectroscopy showed that oxalic acid is molecularly adsorbed on the Cu surface. The results obtained from these studies provide a better understanding of atmospheric reactions at a molecular level and enable an assessment of the relative importance of the reactions in the atmosphere.