热喷雾进样火焰原子吸收光谱法测定河水中的铅

铅被广泛应用于蓄电池、建筑材料、电缆外套等工业生产中,是造成河水污染的主要原因。铅为生物体有害元素,当其被人体组织吸收后,分布予肝、肾、肺、脑中,损害骨髓造血系统和神经系统。在环境检测中铅是必须检测的元素之一。火焰原子吸收光谱法具有仪器简单、操作方便、抗干扰能力强、稳定性好等特点,但由于雾化效率低和灵敏度低,不能直接用于测定样品中的低含量铅。     

佛山市蔬菜中若干重金属元素含量调查与分析

对广东佛山市蔬菜中重金属含量进行了调查与分析。结果表明,蔬菜中重金属元素含量取决于蔬菜种类和土壤环境,佛山市蔬菜中重金属元素含量基本上是正常的,仅个别样点土壤受污染,蔬菜重金属元素含量异常。蔬菜中重金属元素含量由高到低顺序大体上是:叶菜类,瓜果类蔬菜,根菜类蔬菜。蔬菜必需元素锌、铜含量比汞、镉、铅、铬、镍等非必需元素含量高。     

学龄儿童智商与微量元素含量关系研究

为了解头发微量元素含量与学龄儿童智商之间的关系,本文测定了深圳市某小学570名7－13岁低智商儿童和正常儿童的IQ值及其头发中七种元素（I、Zn、Fe、Cu、Ca、Mn、Pb）的含量,并对低智商儿童及正常儿童头发中的元素含量作了比较。结果表明,低智商儿童头发碘、锌、钙的含量显著低于正常儿童头发中的含量,而发铅则显著高于正常儿童的含量。说明儿童智商高低与机体碘、锌、钙以及铅的含量有密切关系。     

分析测试经验介绍(214~218)电感耦合等离子体发射光谱法测定18K金中铅元素的谱线选择

18K金中可能含有多种杂质元素, 如铜和铅.常用的光谱分析方法中, 铅元素测试谱线易被铜、铁和金等元素干扰.建立了基于电感耦合等离子体原子发射光谱法(ICP-OES)测定18K金中铅含量的方法.测试结果表明, 在283.306 nm谱线下, 铅元素在标准曲线浓度范围内呈良好线性关系.方法检出限为0.005 6 μg/mL, 加标回收率在92.9%~102.0%之间, 相对标准偏差小于1%.采用283.306 nm谱线测试结果准确, 灵敏度高, 适用于测试18K金中铅元素含量.     

中医常见病症患儿及体检儿头发元素分析

探讨了中医常见病症患儿及体检儿头发元素含量 ,发现不论是男性还是女性中医常见病症患儿 ,以及男女性体检儿头发八种元素与正常值比较 ,其头发中锌、锰含量均较正常值低 ,而宏量元素钙在各组中都高于正常值 (P <0 0 1)。非必需微量元素如铅、镉、铝在各组中都明显超过正常值水平 (P均 <0 0 1)。结果提示 ,不论是体检儿还是患病儿 ,都要重视平衡膳食原则 ,既不能盲目进补 ,又不能一味随儿童自己的喜好而选择食物。同时大力提倡保护环境 ,减少环境污染 ,减少铅、镉、铝在体内的吸收 ,已是不容忽视的社会问题。     

低含量铀,钍的X射线荧光光谱法测定

目前仪器分析低含量铀、钍的最佳方法是中子活化,质谱以及激光荧光法。自75年以来,不少研究单位已开始使用X荧光光谱法分析地质样品中的低含量铀和钍。其优点是制样简单,分析速度快,而且除了铀、钍含量外,还可同时测定诸如铷、锶、铅和钾等元素的含量。但到目前为止,人们     

原子吸收法测定高含量铅

高含量铅的测定通常采用容量法。多金属矿石中的高含量铅,则要经过冗长的分离手续,最后以络合滴定法完成测定。原子吸收法(AAS)由于具有干扰少、简便、快速、准确等优点,已广泛应用于低含量元素的测定。近年来国内应用原子吸收法测定高含量无素的实用分析方法已有报导。     

青海种植山茛菪根部重金属元素特征

采集2～7年生人工种植山莨菪,用原子荧光光谱仪测定了镉、砷、汞,原子吸收光谱仪测定铅。结果表明,2—7年生种植山莨菪在每年9月份中,4种重金属元素含量水平由高到低依次为：砷、镉、铅、汞;铅和镉、砷和铅、且砷和镉之间均存在一定相关性。各种重金属的含量随着年份和生物量的增加而有所积累。     

锌的快速络合滴定

锌的络合滴定,对其干扰元素,特别是铅的干扰消除问题,是该法能否快速的关键。本法在低铅试样中于氨性氯化铵介质加入碳酸钠在高铅试样中加碳酸钠和钨酸钠,一次沉淀分离铅、铁、铝、锰,滤液用硫酸调节酸度后进行络合滴定。分析结果与经典黄血盐法(高含量部分)、氨性底液极谱法(低含量部分)比较,     

原子吸收法测定锡铅基焊料中微量元素

锡铅焊料在电子工业、汽车工业、工件焊接以及金属制品的密封防漏和修补等方面有着广泛的用途。对其中锡、铅成份的配比、某些添加元素及杂质元素的含量要求,则因用途而异,所以准确测定这些元素的含量非常重要。Z.Wang等提出用氢溴酸-溴分解试样,光度法测定锡铅焊料中铁、铝、铋、锌、铜等元素,但手续比较繁冗、费时。有的则用光谱法进行分析。本文在J.Y.Hwang工作的基础上,提出以硝酸-氟硼酸-酒石酸的混合溶剂分解试样,用空气-乙炔火焰原子吸收法测定银、铋、镉、铜、铁、锑等杂质元素,解决了锡焊料难溶的困难。基体锡、铅有干扰;而其配比变化对多数杂质元素无显著影响,唯银随基体浓度配比改变有影响,但锡和铅总量不变时对各元素的测定均无影响。所以,本法在绘制工作曲线时,加入与待测试液相当量的锡铅合量为基底,即     

Computational study of the enthalpies of formation, DeltafH degrees, and mean bond enthalpies, mBEs, of H4-nEXn0/- and H3-nEXn+/0 (E=C, B; X=F-I)

To compensate for lacking experimental standard enthalpies of formation DeltafH degrees of haloboranes/-boranates as well as the isoelectronic halocarbenium ions and halomethanes, high-level quantum chemical calculations up to the ccsd(t)/(SDB-)aug-cc-pVQZ level have been performed to establish these values. Very reliable experimental data (e.g., DeltafH degrees of HCl, F, and CH4) or at the G3 level established values (e.g., DeltafH degrees of CF3+=410 kJ mol(-1)) were used as anchor points to obtain accurate absolute DeltafH degrees and mean bond enthalpy (mBE) values. To further minimize systematic errors of the protocol, all derived quantities were assessed in isodesmic reactions at the G3 and ccsd(t) level using the (SDB-)aug-cc-PVTZ basis set. The obtained DeltafH degrees values are in very good agreement to (scarcely available) accurate experimental and computational data. Almost all B-containing compounds have been assessed for the first time. We derived "best" DeltafH degrees values and used them to determine the mean E-X bond enthalpies in H4-nEXn-/0 and H3-nEXn0/+ (with n=1-3, E=B, C, and X=F-I). In each of the series, the DeltafH degrees values increase from fluorine to iodine, and except for the iodine-containing carbenium ions and the bromo- and iodomethanes, the DeltafH degrees values become lower with the more halogen atoms that are present in the particle. The boron containing species always have a lower DeltafH degrees than the isoelectronic carbenium ions and methanes, and the H4-nEXn-/0 are lower in energy than the parent H3-nEXn+/0. This reflects the greater average B-X bond strengths.     

Optical properties of Sm3+ ions doped in tellurite glass

Judd-Ofelt analysis of Sm(3+) ions doped in a tellurite glass has been accomplished. Fluorescence and life-time measurements have been carried out using Ar(+) laser and excimer laser. Stark splitting has been observed in the upper and lower levels in fluorescence. The life-time of 4G(5/2) level as a function of Sm(3+) concentration has been measured. Concentration quenching and the mechanism responsible for the same have been found.     

100例皮肤病患者发样微量元素的检测及多因素分析

对100例皮肤病患者发样中的Zn、Cu、Fe、Ca及Mg五种元素进行了检测，采用主成分分析及因子分析法对分析数据进行了统计学处理，探索皮肤病与该五种元素的关系，结果表明：Zn、Mg元素水平是皮肤病的重要样本特征，其中Mg元素是皮肤病的一个重要影响因子。其水平偏高及偏低者占病例数的92％；Cu、Fe元素水平基本正常；缺Zn影响则不是主要因素，低Zn者只占8％。可将皮肤病分为两大类：(1)Zn、Mg元素水平偏高类；占病例数的58％。(2)Ca、Mg元素水平偏低类，占病例数的32％。     

NMR and UV studies of 4-thio-2'-deoxyuridine and its derivatives

5-Substituted-4-thio-2'-deoxyuridine nucleosides have been chemically synthesized and studied by NMR and UV spectroscopy. The results have been analyzed and discussed in connection with the previous data. The imino proton signal and the carbon signal of the thiocarbonyl group in the 5-substituted-4-thio-2'-deoxyuridines were found to be at much lower field, offering a potential for monitoring these modified bases at the DNA level. All 4-thionucleosides have strong absorptions at around 340 nm and consequently would be useful as potential UVA-induced anticancer agents.     

小儿反复呼吸道感染与微量元素的关系探讨

为探讨小儿反复呼吸道感染(RRI)与微量元素的关系，测定了35例反复呼吸道感染患儿血中微量元素的含量，并与32例健康儿作对照。结果表明，反复呼吸道感染组(RRI)血锌明显低于健康组儿童血锌，P＜0．05，有显著性差异。提示低锌的小儿易患反复呼吸道感染。     

Reasons of different colors in the ignimbrite lithology: micro-XRF and confocal Raman spectrometry method

Medium to large volume ignimbrites usually show vertical changes in terms of color, mineral components, texture and geochemistry. Determination of vertical changes in single extensive ignimbrite flow unit is difficult and requires careful studies. Color changes in ignimbrite flow units are very important for earth scientists. This may cause to identify the same ignimbrite series with different definition. Incesu ignimbrite has a wide distribution in the Central Anatolian Volcanic Province (CAVP). It is classified into three levels as lower, middle and upper according to color and welding degree. There is a sharp contact between the lower and middle level. The lower level is dark brown to black in color and the middle level has pinkish red to red color. The present paper focuses on the investigation of color changes between the ignimbrite levels by using micro-XRF and confocal Raman spectrometry. Micro-XRF and Raman spectrometry studies were performed on the polished thin sections of the lower and middle levels with different compositions. These differences were because of the compositional changes of K and slightly Fe elements distribution within the matrix. The dark brown to black color of the lower level was related to the high concentration of the K and Fe relatively to the middle level. Confocal Raman spectrometry investigations exhibited the matrix of the lower level mainly composed of anorthoclase, supporting the results of the micro-XRF.     

Quantitative analysis of fatty acid methyl esters and dimethyl acetals on a polar (free fatty acid phase) capillary column

Separation of fatty acid methyl esters and dimethyl acetals from complex biological samples has been achieved by gas-liquid chromatography on a capillary column coated with free fatty acid phase. Response-correcting factors were determined, showing rather large variations with fatty acid length. Polyunsaturated fatty acid methyl esters were shown to have lower responses than saturated species, whereas dimethyl acetals and equivalent methyl esters were found to give similar responses. Total fatty acid and aldehyde compositions of human and simian erythrocytes were determined and compared, showing a somewhat higher level of linoleate and arachidonate, and a lower level of plasmalogens in simian erythrocytes.     

Synthesis of (±)-negamycin and of (±)-epinegamycin

The antibiotic negamycin and its diastereomer have both been synthesized in racemic form. The latter has been found to possess antibacterial activity, but at a lower level than negamycin itself.     

Single cell green algae reference materials with managed levels of heavy metals

Three batches of single cell green algal biomass have been produced as model substances for green biomass reference materials with the aim of arriving at three different concentration levels for selected heavy metals in the same matrix. The green algal biomass is produced in a water based culture medium in open and closed bioreactors. An outdoor open bioreactor technology was used to produce a batch of “natural level” algae as well as a batch with elevated levels of As, Cd, Cr, Hg, Ni, and Pb. A photoreactor constructed without metal parts and employing artificial light sources was used in a clean air environment with high purity chemicals to reduce heavy metal concentrations in the third batch of algal biomass. For the above elements, the depleted level material, with exception of Hg, showed about one order of magnitude lower concentration than the natural level, while concentrations in the enriched material were up to four orders of magnitude higher. Analysts can use these materials to sustain verification of calibration and analytical quality over the entire operational range of the analytical work.