Trends in surface and interface analysis

Summary The rapid progress in high technology constantly poses new challenges for Analytical Chemistry and prompts the development of new techniques and procedures. The influence is particularly strong in surface and interface analysis, which is developing at a rapid pace. This paper discusses some of the frontier areas like high-resolution depth-distribution analysis of trace elements, quantitative depth distribution analysis of ultra thin-layer systems, quantitative trace element analysis in monolayers, 3-dimensional stereometric analysis, molecular analysis, in-situ atomic resolution analysis of surfaces (chemical nanoscopy). Methodological approaches are discussed as well as results obtained mainly with solid state mass spectrometry and atomic force microscopy.Abbreviations and acronyms AES Auger Electron Spectrometry - AEM Analytical Electron Microscopy - AFM Atomic Force Microscopy - BSE Back Scattered Electrons - EPMA Electron Probe Micro Analysis - LRI-SNMS Laser Resonance Ionization Sputtered Neutrals Mass Spectrometry - SE Secondary Electrons - SEM Scanning Electron Microscopy - SIMS Secondary Ion Mass Spectrometry - STM Scanning Tunneling Microscopy - TEM Transmission Electron Microscopy - TOF-MS Time-of-Flight Mass Spectrometer - TXRF Total Reflection X-Ray Spectrometry - XPS X-Ray Photoelectron Spectroscopy Dedicated to Professor Dr. Wilhelm Fresenius on the occasion of his 80th birthday     

Mechanism of the Anionic Ring-Opening Oligomerization of Propylene Carbonate Initiated by the tert-Butylphenol/KHCO3 System

The ring-opening oligomerization reaction of propylene carbonate in the presence of the tert-butylphenol/KHCO₃ initiating system was studied by means of Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS) and Electrospray Ionization Time of Flight Mass Spectrometry (ESI-TOF MS). According to the MS spectra obtained, different series of peaks were identified. The MS spectra clearly showed that besides the chain-extension reaction yielding oligomers with all propylene oxide units, the formation of oligomers containing carbonate linkages in the chain, and condensation reaction between the latter two also took place. The structure of the oligomers carrying carbonate linkages was determined by the post-source decay (PSD) MALDI-TOF MS/MS method. Based on the MS results, a mechanism for the oligomerization reaction is proposed.     

An integrated digital microfluidic chip for multiplexed proteomic sample preparation and analysis by MALDI-MS

To realize multiplexed sample preparation on a digital microfluidic chip for high-throughput Matrix Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI-MS), several fluidic functions need to be integrated. These include the generation of multiple droplets from a reservoir and parallel in-line sample purification. In this paper, we develop two critical new functions in handling protein solutions and standard proteomic reagents with electrowetting-on-dielectric (EWOD) actuation, leading to an integrated chip for multiplexed sample preparation for MALDI-MS. The first is a voltage sequence designed to generate a series of droplets from each of the three reservoirs--proteomic sample, rinsing fluid, and MALDI reagents. It is the first time that proteomic reagents have been dispensed using EWOD in an air (as opposed to oil) environment. The second is a box-in-box electrode pattern developed to allow droplet passing over dried sample spots, making the process of in-line sample purification robust for parallel processing. As a result, parallel processing of multiple sample droplets is demonstrated on the integrated EWOD-MALDI-MS chip, an important step towards high-throughput MALDI-MS. The MS results, collected directly from the integrated devices, are of good quality, suggesting that the tedious process of sample preparation can be automated on-chip for MALDI-MS applications as well as other high-throughput proteomics applications.     

高分辨率电喷雾飞行时间质谱测定丹参脂溶性组分

丹参 [1] (Salvia miltiorrhiza Bage)为唇形科鼠尾草属多年生草本植物 ,临床上用于治疗妇科病、冠心病、缺血性中风及动脉粥样硬化等症 .近年来 ,飞行时间质谱 (TOF- MS)的分辨率优于 1 0 4 [2 ] ,尤其是再配合 ESI/MAL DI/APCI及新型脉冲电喷雾 [3 ]等离子源 ,使之成为当今最     

芍药苷的电喷雾串联质谱研究

采用电喷雾串联质谱(ESI-MSn)技术, 结合H/D交换方法, 在正、负离子检测模式下对白芍药材中主要成分芍药苷的质谱裂解规律进行了系统研究. 实验结果表明, 该化合物在正、负离子模式下均得到较好的质谱信息, 且在正离子模式下, 电喷雾质谱分析的灵敏度更高. 同时获得了其质谱裂解规律, 为白芍中其它化合物的分析鉴定提供了有效的质谱方法.     

New aspects of determination of polymer heterogeneity by 2-Dimensional orthogonal liquid chromatography and maldi-tof- MS

Liquid Adsorption Chromatography at Critical Conditions (LACCC) of polymers in combination with Matrix-Assisted Laser Desorption / Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF-MS) and different types of detectors is a very convenient method for the characterization of polymer heterogeneities. A pathway for working out these methods is given. Additionally to the coupling of different chromatographic modes a device for post-column reaction detection is described and applied. Examples of applications are given for aliphatic and aromatic polyesters. MALDI-TOF-MS, reaction detection and relations between “critical” solvent composition and structure of polyesters are discussed. Conclusions concerning the mechanism of thermal degradation of polylactides are shown.     

Uranium submicrosample isotopic analysis by TIMS

A technique for isotopic submicrosample analysis of uranium by TIMS is presented. The heating pattern, used was modified in order to improve the precision for microsample analysis of SRM U-500 /NBS/ The technique was applied to submicrosample isotopic analysis of SRM U-150 /NBS/ and found satisfactory.Thermal Ionization Mass Spectrometry.     

Laser ionization mass spectrometry in inorganic trace analysis

Summary Among the different spectrometric techniques for trace analysis Laser Ionization Mass Spectrometry (LIMS) is well established as a trace analytical method. With the LIMS technique the sample material is evaporated and ionized by means of a focused pulsed laser in a laser microplasma, which is formed in the spot area of the irradiated sample. All chemical elements in the sample materials are evaporated and ionized in the laser plasma. The ions formed are separated according to their mass and energy by a time-of-flight, quadrupole or double focusing mass spectrometer. In this review the characteristics and analytical features, some recent developments and applications of laser ionization mass spectrometry in inorganic trace analysis are described.     

电喷雾萃取电离质谱在线监测 Friedl?nder 缩合反应

质谱在线监测有机化学反应能够实时捕捉反应过程中反应物、中间体、产物的信号及其变化情况,从而推测有机反应机理,并加深对反应本质的认识。本研究利用电喷雾萃取电离质谱(EESI-MS)技术在线监测草酸催化的邻氨基苯乙酮与乙酰丙酮间的Friedlnder缩合反应。在反应的不同时间点,分别捕捉到了反应物(m/z 136)、中间体(m/z 218、m/z 236)和产物(m/z 200)的准分子离子信号,并记录了它们的信号强度随反应时间的变化趋势,推测出了反应机理。     

A critical analysis of electrospray techniques for the determination of accelerated rates and mechanisms of chemical reactions in droplets

Electrospray and Electrosonic Spray Ionization Mass Spectrometry (ESI-MS and ESSI-MS) have been widely used to report evidence that many chemical reactions in micro- and nano-droplets are dramatically accelerated by factors of ∼10² to 10⁶ relative to macroscale bulk solutions. Despite electrospray''s relative simplicity to both generate and detect reaction products in charged droplets using mass spectrometry, substantial complexity exists in how the electrospray process itself impacts the interpretation of the mechanism of these observed accelerated rates. ESI and ESSI are both coupled multi-phase processes, in which analytes in small charged droplets are transferred and detected as gas-phase ions with a mass spectrometer. As such, quantitative examination is needed to evaluate the impact of multiple experimental factors on the magnitude and mechanisms of reaction acceleration. These include: (1) evaporative concentration of reactants as a function of droplet size and initial concentration, (2) competition from gas-phase chemistry and reactions on experimental surfaces, (3) differences in ionization efficiency and ion transmission and (4) droplet charge. We examine (1–4) using numerical models, new ESI/ESSI-MS experimental data, and prior literature to assess the limitations of these approaches and the experimental best practices required to robustly interpret acceleration factors in micro- and nano-droplets produced by ESI and ESSI.

The application of Electrospray and Electrosonic Spray Ionization Mass Spectrometry (ESI-MS and ESSI-MS) to study accelerated reaction kinetics in droplets is examined using numerical models, new experimental data, and prior literature.     

Ultratrace and microdistribution analysis in material sciences

Summary All-rounders and experts are two basic types of scientists. A harmonic cooperation between these two groups is essential for today's large study groups engaged in materials development. Materials development programmes in many high-tech countries are major fields of research supported by special financial arrangements (e.g. COST, EURAM or BRITE-programmes in Europe). Modern materials development is not possible without analytical guidance. This is not always realized by all engaged partners and it is a main obligation of analytical chemists to make aware of the role of a potent materials characterization in relevant development programmes. This should be demonstrated in two essential relevant areas: a) Bulk trace and ultra trace analysis of metals. Many important metal properties are directly or indirectly influenced by trace elements. In complex systems like fusion reactors or microelectronic components, trace contents of even minor metal parts might decisively influence system properties. As refractory metals and their silicides gain rising importance in VLSI microelectronic applications, their ultratrace characterization becomes a major challenge. Essential progress was possible by the complementary application of mass-spectrometric methods. Latest results and a critical survey will be given, including GDMS, SIMS, SSMS, IDMS and ICP-MS.Surprisingly, however, highest sensitivities and best detection limits were recently achieved by a combination of trace-matrix separation procedures and final end determination with ICP-MS. This combination also proved to be the most economic and safest approach from the view point of accuracy and precision. b) The analytical characterization of discontinuities and heterogeneities in solid matter. Practical examples are again taken from the study of refractory and hard metals and ceramics. A survey is given as to the manifold effects, heterogeneities and discontinuities exert on modern high-tech materials: as a function of their average diameter, they can either strengthen the material (dispersion strengthening), or they can cause deterioration of material properties e.g. as points of crack initiation, by grain boundary embrittlement etc. Together with most important methods for detection and characterization of heterogeneities and discontinuities, their evaluation and possible prevention during materials fabrication are discussed and pertinent examples are given. The phenomena of heterogeneous particles and pores are elucidated in more detail.

Acronyms used

1 Abbreviations for European research programmes AGATA Advanced Gas Turbines for Automobiles - BRITE Basic Research for Industrial Technologies for Europe - COST Cooperation in Science and Technology - EURAM European Research Activities Programme on Materials 2 Abbreviations in the field of refractory metals technology ADM Ammonium-Di-Molybdate - APT Ammonium-Para-Tungstate - HP High Purity - MHC Molybdenum-based alloy containing 1.2% Hf and 0.1% C - NS Non-sag (tungsten, used for lamp filaments and evaporative metallization techniques) - ODS Oxide Dispersion Strengthened - RM Refractory Metal - TZM Molybdenum-base alloy containing 0.5% Ti, 0.08% Zr and 0.025% C - UHP Ultra High Purity - VLSI Very large scale integration - ZHM Molybdenum-base alloy containing 0.40% Zr, 1.2% Hf and 0.15% C 3 Analytical technique names AA Activation Analysis - AAS Atomic Absorption Spectrophotometry - AES Auger Electron Spectrometry or Atomic Emission Spectrometry (only used in this work where it is clear that Auger Electron Spectrometry is not meant) - EDX(RS) Energy Dispersive X-Ray Spectrometry - EELS Electron Energy Loss Spectrometry - EP(X)MA Electron Probe X-Ray Microanalysis - GDMS Glow Discharge Mass Spectrometry - GFAAS Graphite Furnace Atomic Absorption Spectrometry - ICP-OES, MS Inductively Coupled Plasma — Optical Emission Spectrometry, Mass Spectrometry - ID-MS Isotope Dilution — Mass Spectrometry - LAS Classical photometry (Liquid Absorption — Spectrophotometry) - LEED Low Energy Electron Diffraction - MS Mass Spectrometry - NAA Neutron Activation Analysis - OES Optical Emission Spectrometry - SEM Scanning Electron Microscopy - SIMS Secondary Ion Mass Spectrometry - SSMS Spark Source Mass Spectrometry - TEM Transmission Electron Microscopy - TMS Trace-Matrix Separation (procedure) - WLD(-XRS) Wave Length Dispersive — XRS - XR(F)S X-Ray (Fluorescence) Spectrometry     

Experimental evaluation of239Pu,238Pu and233U spikes for determining plutonium concentration by thermal ionization mass spectrometry and alpha-spectrometry

Experimental evaluation on the use of²³⁹Pu spike in Isotope Dilution-Thermal Ionization Mass Spectrometry (ID-TIMS),²³⁸Pu spike in Isotope Dilution Alpha Spectrometry (IDAS) and²³³U as a Non-Isotopic Diluent in Alpha Spectrometry (N-IDAS), for determing plutonium concentration in samples with burn-up values in the range of 1,000–10,000 MWD/TU is done. Precision is determined by analyzing replicate aliquots from different samples using each of the three spikes. Accuracy is established by comparing the results with those obtained by using well recognized spike²⁴²Pu in ID-TIMS. It is shown that the use of²³⁹Pu spike with the latest generation thermal ionization mass spectrometers gives the best precision (0.2%), whereas the precision values of 0.5 and 1% can be obtained by using²³⁸Pu and²³³U spikes, respectively, on a routine basis. Reasons for the difference in the precision values are discussed, along with the merits and drawbacks on the use of different spike isotopes.     

Accurate measurement of neodymium isotopic composition using Neptune MC-ICP-MS

This paper reports the measurement of the Neodymium isotopic composition by Neptune Multiple Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS) over the last two years. Although there is concomitant Cerium in the chemical separation process, this has no significant influence on the Neodymium analysis. As for the sample containing small amounts of Samarium (Sm/Nd < 0.04), direct calibration for isobaric interference and mass discrimination by the exponential law can be obtained by assuming that Samarium mass discrimination is the same as that of Neodymium. Geological samples after traditional chemical separation were measured by Neptune MC-ICP-MS and Thermal Ionization Mass Spectrometry (TIMS) respectively. The results show that Neptune MC-ICP-MS can measure Neodymium isotopic composition as precisely the TIMS does and is even more effective and less time-consuming than the TIMS Method. __________ Translated from Chinese Journal of Analytical Chemistry, 2007, 35(1): 71–74 [译自: 分析化学]     

Extended mass range by multiple charge: Sampling quadruply charged quasimolecular ions of poly(ethylene glycol) 4000

Mass spectrometric sampling of quasimolecular ions with charge as high as 4+ has been achieved by Electrohydrodynamic Ionization Mass Spectrometry (EHMS). Triply and quadruply charged sodium ion adducts of poly(ethylene glycol) 4000 oligomers with mass exceeding 3500 u were sampled from glycerol solution without fragmentation. Although the mass of these ions exceeded the nomical mass range of the spectrometer, they were detected because of multiple charge which lowered their mass-to-charge ratio. From the mass spectral intensities of these oligomer ions, the number average molecular weight of the polymer was caculated, and found to be in good agreement with results of an ASTM standard method.     

Direct observation of the formation of aromatic pollutants in waste incineration flue gases by on-line REMPI-TOFMS laser mass spectrometry

On-line REMPI-TOFMS laser mass spectrometry (Resonance Enhanced Multi-Photon Ionization – Time-Of-Flight Mass Spectrometry) was used to monitor combustion and pyrolysis byproducts from industrial combustion processes, including polycyclic aromatic hydrocarbons (PAH) and monochlorobenzene in the flue gas of an industrial 22 MW hazardous waste incineration plant. Sampling at different places in the flue gas stream revealed the complexity of the processes responsible for the formation of the different chemical species, while time resolved measurements depicted the emission dynamics.     

质谱成像技术在肿瘤研究中的应用进展

质谱成像(Mass spectrometry imaging,MSI)作为一种新型的分子成像技术,具有无需标记、无需复杂样品前处理、高通量等优点,可实现脂类、代谢物等的直接分析,并可获得组织切片中物质的空间分布信息,已成为生物、医学等领域研究的有力工具。离子化技术是质谱成像的关键和核心,新型质谱成像离子化技术的不断涌现,推动了质谱成像技术在肿瘤研究中的应用。该文着重介绍了当前主要质谱成像技术的原理及特点,并对其在肿瘤的病理诊断、标志物、药物研究等方面的应用进行评述,为质谱成像技术在肿瘤方面的研究提供参考。     

A Comparison Between Chemical Ionization And Electron Impact Techniques Of Mass Spectrometry For The Estimation Of N-Nitrosodimethylamine

Abstract

Some beverage and meat products are examined for the presence of N-nitrosodimethylamine by both Low- and High- Resolution Chemical Ionization Mass Spectrometry, compared with that by Electron Impact method to assess their reliability. All the data obtained from these MS methods have been treated by Statistical analysis, and the result obtained shows that the variances are not significant between each other, but the Low- Resolution Electron Impact MS with single ion monitoring gives rise to inconsistency among them.     

生物质谱--蛋白质组研究的关键技术

介绍了近几年来国际上重点研究的几类新型生物质谱技术,综述了它们在蛋白质组研究中的最新进展,比较了各自的特点,简要评价了它们在蛋白质组研究中的应用和前景。     

Direct Analysis of Large Living Organism by Megavolt Electrostatic Ionization Mass Spectrometry

A new ambient ionization method allowing the direct chemical analysis of living human body by mass spectrometry (MS) was developed. This MS method, namely Megavolt Electrostatic Ionization Mass Spectrometry, is based on electrostatic charging of a living individual to megavolt (MV) potential, illicit drugs, and explosives on skin/glove, flammable solvent on cloth/tissue paper, and volatile food substances in breath were readily ionized and detected by a mass spectrometer. Figure

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Comparison of NTIMS and ICP-OES methods for the determination of boron concentrations in natural fresh and saline waters

Determination of B concentrations in natural fresh and saline waters by ICP-OES may be strongly affected by matrix effects resulting in a deviation (shift to apparently lower values) in the order of 10 to 20% (if working without matrix-matched standard solutions), at variance with the NTIMS (Negative Thermal Ionization Mass Spectrometry) isotope dilution technique which is virtually unaffected by such effects. NTIMS isotope dilution is a highly sensitive, precise and effective technique which requires only trace amounts of boron (1–10 ng B) and allows boron concentrations in natural waters to be analyzed with an analytical uncertainty of ± 2% (2 σ).