Capillary electrophoresis-inductively coupled plasma-mass spectrometry: an attractive complementary technique for elemental speciation analysis

Some basic and practical aspects of interfacing capillary electrophoresis to inductively coupled plasma-mass spectrometry (CE-ICP-MS) are reviewed in this article with emphasis on the use of this hyphenated technique for elemental speciation analysis. The principles behind the techniques of both CE and ICP-MS are introduced. The interfacing of CE to ICP-MS is discussed including several devices and nebulizers reported in literature. A brief account of their advantages and limitations is given. The various CE-ICP-MS applications for elemental speciation analysis are also reviewed. Some issues concerning the future of CE-ICP-MS for the elemental speciation analyses are discussed.     

碳和硼的笼状原子簇及其关系

碳笼烯C_(60)的发现及碳笼烷C-(60)H_(60)的制备,激励人们去探索合成新的碳元素类似物和其它元素的类似物。本文利用碳和硼的笼型烷烃的化学键和几何特征,讨论碳和硼的笼状原子簇骨架的共轭关系,推导其中一些高对称化合物的原子数和几何结构,并讨论其稳定性。 1 碳和硼的笼状原子簇骨架的共轭关系     

Determination of elemental selenium and pyrite-selenium in sediments

A method is described for the selective determination of concentrations of elemental selenium and pyrite-selenium in sediments. A 1 M sodium sulfite solution is used to solubilize elemental selenium and a Cr(II) solution releases selenium in pyrite. The accuracy of the methods was evaluated by using various selenium compounds. The detection limits for the elemental and pyrite-selenium procedures are 0.001 and 0.025 μg Se per gram of sediment, respectively. The relative standard deviationis < 10% for elemental selenium and < 16% for pyrite-selenium. These and other procedures were used for selenium speciation in marine and freshwater sediments.     

柴油非加氢脱硫技术研究中样品的选择

利用气相色谱/原子发射光谱检测器（GC/AED），对小型加氢装置的加氢脱硫柴油样品及氧化/萃取前后样品油中含硫化合物进行了分析，对色谱图中出现的几个可疑峰进行了分析和推测，表明这几个峰是由元素硫产生的，并通过无硫油样中加入硫磺和对样品进行汞洗等实验进行了验证。此外，对于加氢柴油中元素硫产生原因以及对硫质量分数测定和对实验分析的影响，在氧化脱硫等非加氢脱硫实验中样品的选择等问题进行了讨论。     

有机元素分析中影响燃烧过程的因素

燃烧过程是有机元素分析中十分重要而又较难把握的一个步骤。本文介绍了有机元素分析中影响燃烧过程的因素及控制方法。     

Mass-spectrometric elemental analysis of solid substances in Russia

The review surveys the achievements of Russian scientists in mass-spectrometric analysis made in the past decade. Attention is focused on direct and indirect methods for the elemental analysis of solid and powdered materials. Among them are mass-spectrometric elemental analysis techniques with spark, laser, glow discharge, and inductively coupled plasma ionization. The applications of the above techniques to various areas of science, technology, and industry are described, in particular, the elemental analysis of nuclear technology materials, the determination of trace impurities in high-purity substances, some applications in medicine, biology, ecology, and basic research. Some achievements in the mass-spectrometric technique for the determination of the elemental composition of solid and powdered materials are considered. Some characteristics of methods are given: the range of the analyzed elements, errors in the determination of concentrations, and the limit of detection.     

The potential and challenges of elemental speciation by capillary electrophoresis-inductively coupled plasma mass spectrometry and electrospray or ion spray mass spectrometry

Capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS) and electrospray (ES) or ion spray (IS) mass spectrometry (MS) are recently introduced techniques for elemental speciation. Both techniques have the potential for rapid elemental speciation with low detection limits. Examples of the use of CE-ICP-MS for elemental speciation of positive, neutral and negative species are discussed. Issues in interfacing CE and ICP-MS are considered briefly. The potential advantages and disadvantages of laminar flow in CE-ICP-MS are examined. Potential difficulties in CE-ICP-MS including loss of sample, chemical matrix effects and changes in speciation during separation are discussed. The interpretation of ES or IS-MS spectra and analysis of complex mixtures are considered. Calibration and chemical matrix effects are assessed. Potential pitfalls of interpreting bare metal ion spectra as elemental analysis are discussed. The need for fundamental understanding of the processes that control ES and IS-MS signals is examined. High conductivity samples currently present difficulties for CE-ICP-MS or ES and IS-MS.     

The thermolysis of dicarbonylcyclopentadienyliron dimer: The formation of biferrocene

The thermolysis of dicarbonylcyclopentadienyliron dimer in a sealed tube at 300°C has been reported to produce ferrocene, carbon monoxide, carbon dioxide, cyclopentadiene and elemental iron. We observe in addition to these products the production of biferrocene and elemental carbon. Thermolysis of carbonylcyclopentadienyliron tetramer (produced from the dimer by thermolysis in refluxing xylene) produces ferrocene, iron and carbon monoxidre; no biferrocene, carbon dioxide or elemental carbon are produced. A scheme is proposed to account for these products.     

Determination of elemental sulfur, mercaptan and disulfide in petroleum naphtha by differential-pulse polarography

Summary The polarographic behaviour of elemental sulfur, mercaptan and disulfide in 0.032 mol/l sulfuric acid-ethanolnaphtha is described. The peak potentials for elemental sulfur and mercaptan are about 200 mV apart, which allows simultaneous determination of these compounds. The calibration plot is linear up to 1 mg·1^–1 for elemental sulfur and it is a curve depending on molecular weight for mercaptan. The disulfide present a peak close to the peak of the mercaptans but with a lower sensitivity and therefore they do not interfere. The polarographic properties, diffusion, reversibility and electrocapillary curves are discussed.     

Plasma spectrometry for elemental speciation and characterization in beverages

A review is presented on recent applications of plasma spectrometric techniques for speciation analysis in beverages. The 3 most common ways of characterizing beverages in addition to elemental speciation are also discussed: total element analysis, isotope ratio, and statistical characterization. To date, most of the elemental characterization in beverages with plasma techniques has been performed in the statistical evaluation of wines and in teas. However, despite the increasing interest in elemental speciation, most of the plasma-based techniques in beverage studies are used for total metal detection and the full capabilities of inductively coupled plasma techniques have yet to be realized.     

Absolute quantitative electron microscopy of thin biological specimens by energy-dispersive x-ray microanalysis and densitometric mass determination

The method described is capable of measuring both the absolute mass and the mass fraction of elements is isolated thin biological specimens. To determine the elemental mass, characteristic x-rays emitted under electron irradiation are used, whereas the total mass of the specimen is found from electron scattering. Comparison with measurements on standards allows the calculation of the absolute elemental mass and elemental mass fraction values. The number of x-ray quanta per atom of a particular element, detected under strictly standardized procedural conditions, is given by a unit x-ray count value. Such values were determined for magnesium, phosphorus, sulfur and calcium using spray droplets as standard specimens.     

药学专业元素化学教学方法探究

元素化学是药学专业无机化学的重要组成部分,其内容繁多,规律性不强,传统教学方式枯燥乏味,影响了学生的学习兴趣。笔者针对这些问题,结合多年的教学经验,从优化教学内容和教学方法等方面对元素化学教学进行了探究。     

三维编织C/SiC纤维复合块材的XPS研究

用常规XPS、小面积XPS和成象XPS研究了三维编织的C/SiC纤维复合材料.结果表明,在燃气中灼烧后材料表面生成的暗红色反应是由于层中的SiC已氧化成氧化硅,同时反应层中还引入了杂质Fe、Na、Ca和Al;在反应层下Si以元素Si、SiC和氧化硅多种形式存在.块材横截面的多点小面积XPS分析结果表明,元素硅的相对浓度随深度增加而减少, SiC的相对浓度则随深度增加而增加.块材横截面的成象XPS分析清楚地显示了SiC 在纤维束边界间呈大致均匀的分布,在块材两边元素Si的浓度明显偏高.根据XPS象的线性扫描结果估计了纤维束、束间SiC层和块材边缘元素Si富集层的厚度.     

Fluorination of Organic Compounds with Cobalt Trifluoride and Elemental Fluorine in the Presence of Cobalt Trifluoride

Fluorination of organic compounds with cobalt trifluoride and elemental fluorine in the presence of cobalt trifluoride was studied. Fluorination with elemental fluorine proceeds under external-kinetic control at a constant rate. Examples of fluorination with elemental fluorine of certain fluorinated olefins and polyfluorinated paraffins in the presence of CoF₃ are presented.     

Progress of laser ionization mass spectrometry for elemental analysis — A review of the past decade

Mass spectrometry using a laser ionization source has played a significant role in elemental analysis. Three types of techniques are widely used: high irradiance laser ionization mass spectrometry is capable of rapid determination of elements in solids; single particle mass spectrometry is a powerful tool for single particle characterization; and resonance ionization mass spectrometry is applied for isotope ratio measurements with high sensitivity and selectivity. In this review, the main features of the laser ablation process and plasma characterization by mass spectrometry are summarized. Applications of these three techniques for elemental analysis are discussed.     

磁性离子印迹技术用于元素形态分离分析

元素的形态决定了其在环境和生物过程中的不同行为,形态分析正在被分析化学、环境化学、地球化学、生态学、农学和生物医学等众多学科所关注。环境和生物样品基质复杂、化学形态多样、含量低且易转化是元素形态分析面临的挑战,因此对元素形态的甄别、定量、生态毒性评价和生理功能研究需要对原生形态进行高选择性识别和高效率分离。固相萃取是一种有效应对以上难题的方法,但现有材料和方法远不能满足要求。离子印迹聚合物可与印迹金属离子特异性结合,具有准确、灵敏、可靠的特点,近年来在元素形态分离富集和分析检测方面得到了较为广泛的应用。鉴于非磁性吸附剂在固相萃取操作时,需要将分散在样品溶液中的吸附材料经过离心或过滤分离,操作比较繁琐费时,而磁性材料易被外部磁场快速分离,因此操作简便快速的磁固相萃取正成为元素形态分离富集中一种极具潜力的方法。这篇综述系统总结了离子印迹技术的最新进展,包括离子印迹技术的原理、离子印迹聚合物的制备方法,并根据元素形态分析中离子印迹磁固相萃取的发展现状,分析了离子印迹技术所面临的挑战,最后对元素形态分析中离子印迹技术的未来发展方向和策略提出了建议,提出开发基于有机-无机杂化聚合的多功能磁性离子印迹纳米复合物用于样品的前处理是建立识别选择性高、分离能力强、吸附容量大、形态稳定性好的形态分析方法的一种重要举措。     

ICP-MS for elemental speciation studies

The use of inductively coupled plasma mass spectrometry (ICP-MS) coupled with separation techniques for the purpose of elemental speciation has recently gained a lot of attention. Much of this is due to ever improving separation capabilities of Chromatographic techniques, the high sensitivity of ICP-MS, and the continuing development of better interface techniques. Additionally, there is a growing awareness of the need to monitor various species of an analyte, rather than just total analyte concentrations, due to their often varying natures. For the sake of learning from different elemental speciation approaches, this review brings together some selected types of elemental speciation which have been recently seen in literature. These include separations using various forms of liquid chromatography, such as reversed phase, reversed phase ion pairing, micelle, ion exchange, and size exclusion. Elemental speciation employing gas Chromatographie separations and supercritical fluid separations are discussed as well as elemental speciation using capillary electrophoresis.     

Determination of the elemental composition of trace analytes in complex matrices using exact masses of product ions and corresponding neutral losses

The emergence of time-of-flight (TOF) and hybrid quadrupole/time-of-flight (Q-TOF) mass spectrometers has offered new possibilities for determining the elemental composition of analytes present at trace levels. The mass accuracy provided by these instruments is currently in the range of 2-5 m m/z units, permitting the determination of the elemental composition of small molecules. The orthogonal information of relative isotopic abundances (RIAs) is used to reduce the number of elemental compositions that are possible, based on consideration of exact masses. Elimination of additional possible compositions has been reported when the analyte is fragmented and its resulting product ions and corresponding neutral losses are carefully analyzed. Published algorithms reduce the number of proposed precursor ions by deleting each precursor candidate which cannot be explained by summing any combination of postulated product ion and corresponding neutral loss elemental composition candidates. An extension of such algorithms is described in this paper. This approach compares not only the precursor ion with the different fragments, but tests the possible descent of any ion from all other recorded ions. This extended algorithm has been tested by processing published data. Algorithms analyzing product ion spectra can be used for real-life data. However, there is a risk that an ion which originates from the mobile phase or from a co-eluting matrix compound can be mathematically correlated to the investigated precursor ion. Such an incorrect correlation can lead to the deletion of a correct elemental composition. This is an important issue if TOF rather than Q-TOF instruments are used. Therefore, ultra-performance liquid chromatography (UPLC) and a peak deconvolution algorithm were used to generate and process TOF chromatograms in order to minimize the number of ions which are not related to the analyte precursor ion. The combined use of chromatographic deconvolution and product ion spectra has been tested and is critically discussed.     

Influence of elemental sulfur and mercaptans on corrosion of copper strips in the ASTM D-130 test by means of electronic microscopy (SEM) and energy dispersive X-ray (EDX)

Summary Crude petroleum contains sulfur compounds, most of which are removed during refining. The corrosivity of sulfur compounds present in petroleum products is measured by means of the ASTM D-130 copper strip test, which is based on discoloration of a standard copper strip immersed into the petroleum products at 50°C for 3 h. Here the corrosivity of copper strips are tested with elemental sulfur and different mercaptans in synthetic naphtha. The great corrosive power of elemental sulfur is 3.7 times higher than that of ethylmercaptan, the most corrosive among the different mercaptans. The elemental sulfur and ethyl-mercaptan corrosion distribution on copper strips is also studied by means of the ASTM D-130 test together with electronic microscopy (SEM) and energy dispersive X-ray (EDX) techniques. These non-destructive techniques allow to know the strip corrosive morphology and to determine the sulfur concentration on the strip.