原子吸收和原子荧光光谱分析

本文是《分析试验室》期刊定期评述中关于原子吸收光谱(AAS)及原子荧光光谱(AFS)分析的第11篇综述文章. 文中对2004年12月～2007年4月期间我国在AAS/AFS领域所取得的主要进展进行评述. 内容包括概述、仪器装置与数据处理、火焰原子吸收光谱法、电热原子吸收光谱法、化学蒸气发生技术以及原子荧光光谱法等. 收集文献670篇.     

Comparison of stimulated-emission-pumping fluorescence dip spectrometry and conventional fluorescence spectrometry in application to supersonic jet spectrometry

Summary A supersonic jet spectrum of 9,10-dichloroanthracene is measured by stimulated-emission-pumping fluorescence dip spectrometry and conventional fluorescence spectrometry. The performance obtained is compared for these spectrometric methods, providing same information concerned with the energy level of the ground state. The former is more preferential for measurement of a high-resolution spectrum, since the spectral resolution is determined by the linewidth of the dumping laser. On the other hand, the latter is more preferential for measurement with better sensitivity at the expense of the spectral resolution, since the fluorescence throughput can be improved by increasing the slit width of the monochromator.Dedicated to Professor Dr. Wilhelm Fresenius on the occasion of his 80th birthday     

X-ray spectrometry

Summary X-ray spectrometry came only into use in Europe as a practical analytical tool in the mid fifties. Development of electronic detectors and registration during and after World War 2 opened this possibility. The method was slowly introduced into the C.S.I. program, but in 1965 at C.S.I 12 the technique had reached maturity. Tables and figures shown in the 1965 survey paper are presented again together with modern achievements for sensitivity, accuracy and ease of operation. Recent improvements concerning excitation, dispersion and detection are discussed. The tremendous influence of the modern computer on both qualitative and quantitative analysis is illustrated, making modern XRFS a very accurate technique. Emphasis of future development will be focussed on sample preparation and handling, reduction of background, leading to better signal-to-noise ratios, and simplification of calculating procedures.

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RöntgenspektrometrieVergangenheit, Gegenwart und Zukunft

Zusammenfassung Erst in der Mitte der fünfziger Jahre hat die Röntgenspektrometrie in der Industrie Eingang gefunden als praktische Analysenmethode. Die Entwicklung der elektronischen Detektoren und Registriergeräte während des zweiten Weltkrieges hatte dazu die Möglichkeit eröffnet. Diese Methode wurde allmählich in das Programm des C.S.I. einbezogen. Beim C.S.I. 12 im Jahre 1965 war dieser neue Zweig der Atomspektrometrie schon ziemlich weit fortgeschritten. Deswegen werden Tabellen und Abbildungen, die damals in dem Übersichtsvortrag gezeigt wurden, nochmals präsentiert mit neuzeitlichen Ergänzungen und Verbesserungen: Empfindlichkeit, Genauigkeit und Bedienungsfreundlichkeit.Ergebnisse der neuesten Entwicklungen auf dem Gebiete der Anregung, der spektralen Zerlegung und der Registrierung werden gezeigt und erläutert.Die stürmische Einführung der Groß-, Klein-, und Kleinstrechner hat einen sehr großen Einfluß sowohl auf die qualitative wie auch auf die quantitative Analyse ausgeübt, und zwar in einem Maße, daß die XRFS heute als die genaueste Analysenmethode betrachtet werden kann. Weitere Fortschritte können erwartet werden für Probenvorbereitung und Behandlung, Erniedrigung des Untergrundes sowie Berechnung der chemischen Konzentration.

     

Chromatography-mass spectrometry

The review describes the most significant achievements of Russian scientists during last 20 years in developments and improvements of methods combining mass spectrometry and gas chromatography or HPLC for the analysis of organic compounds of different origin in various matrices.     

Electrospray mass spectrometry and tandem mass spectrometry of bimetallic oxovanadium complexes

A series of six bimetallic oxovanadium complexes (1-6; only one was purified) were investigated by electrospray quadrupole time-of-flight tandem mass spectrometry (ESI-QTOF-MS/MS) in negative-ion mode. Radical molecular anions [M](.-) were observed in MS mode. Fragmentation patterns of [M](.-) were proposed, and elemental compositions of most of the product ions were confirmed on the basis of the high-resolution ESI-CID-MS/MS spectra. A complicated series of low-abundance product ions similar to electron impact (EI) ionization spectra indicated the radical character of the precursor ions. Fragment ions at m/z 214, 200, and 182 seem to be the characteristic ions of bimetallic oxovanadium complexes. These ions implied the presence of a V-O-V bridge bond, which might contribute to stabilization of the radical. To obtain more information for structural elucidation, three representative bimetallic oxovanadium complexes (1-3) were analyzed further by MS in positive-ion mode. Positive-ion ESI-MS produced adduct ions of [M + H](+), [M + Na](+), and [M + K](+). The fragmentation patterns of [M + Na](+) were different than those of radical molecular anions [M](.-). Relatively simple fragmentation occurred for [M + Na](+), possibly due to even-electron ion character. Negative-ion MS and MS/MS spectra of the hydrolysis product of Complex 1 supported these finding, in particular, the existence of a V-O-V bridge bond.     

Alpha spectrometry and secondary ion mass spectrometry of electrodeposited uranium films

Electrodeposited natural uranium films prepared by electrodeposition from solution of uranyl nitrate UO₂(NO₃)₂·6H₂O on stainless steel discs in electrodeposition cell. Solutions of NaHSO₄, and Na₂SO₄ and electric current from 0.50 up to 0.75 A were used in this study. Recalculated weights and surface’s weights of ²³⁸U from the alpha activities and secondary ion mass spectrometry (SIMS) intensities resulted in a linear regression. A dependency between of ²³⁸U surface’s weights recalculated from alpha activities and signal intensity of ²³⁸U in SIMS was investigated in order to determine a potential of SIMS in quantitative analysis of surface samples containing uranium. In the SIMS spectra of electrodeposited uranium films we found that upper layer consist not only from isotopes of uranium (ions ²³⁴U⁺, ²³⁵U⁺, and ²³⁸U⁺). In the positive polarity SIMS spectra, various molecules ions of uranium were suggested as UH⁺, UH₂ ⁺, UO⁺, UOH⁺, UO₂ ⁺, UO₂H⁺, UO₂H₂ ⁺, as well as possibly ions UNO⁺ and UNOH⁺.     

Evaluation of micro-electrospray ionization with ion mobility spectrometry/mass spectrometry

In recent years, the resolving power of ion mobility instruments has been increased significantly, enabling ion mobility spectrometry (IMS) to be utilized as an analytical separation technique for complex mixtures. In theory, decreasing the drift tube temperature results in increased resolution due to decreased ion diffusion. However, the heat requirements for complete ion desolvation with electrospray ionization (ESI) have limited the reduction of temperatures in atmospheric pressure ion mobility instruments. Micro-electrospray conditions were investigated in this study to enable more efficient droplet formation and ionization with the objective of reducing drift tube temperatures and increasing IMS resolution. For small molecules (peptides), the drift tube temperature was reduced to ambient temperature with good resolution by employing reduced capillary diameters and flow rates. By employing micro-spray conditions, experimental resolution values approaching theoretically predicted resolution were achieved over a wide temperature range (30 to 250 °C). The historical heat requirements of atmospheric pressure IMS due to ESI desolvation were eliminated due to the use of micro-spray conditions and the high-resolution IMS spectra of GLY-HIS-LYS was obtained at ambient temperature. The desolvation of proteins (cytochrome c) was found to achieve optimal resolution at temperatures greater than 125 °C. This is significantly improved from earlier IMS studies that required drift tube temperatures of 250°C for protein desolvation.     

Mass spectrometry of nanodiamonds

Detonation nanodiamonds (NDs) were studied by time‐of‐flight mass spectrometry (TOF MS). The formation of singly charged carbon clusters, C, with groups of clusters at n = 1–35, n ∼160–400 and clusters with n ∼8000 was observed. On applying either high laser energy or ultrasound, the position and intensity of the maxima change and a new group of clusters at n ∼70–80 is formed. High carbon clusters consist of an even number of carbons while the percentage of odd‐numbered clusters is quite low (≤5–10%). On increasing the laser energy, the maximum of ionization (at n ∼200 carbons) is shifted towards the lower m/z values. It is suggested that this is mainly due to the disaggregation of the original NDs. However, the partial destruction of NDs is also possible. The carbon clusters (n ∼2–35) are partially hydrogenated and the average value of the hydrogenation was 10–30%. Trace impurities in NDs like Li, B, Fe, and others were detected at high laser energy. Several matrices for ionizing NDs were examined and NDs themselves can also be used as a matrix for the ionization of various organic compounds. When NDs were used as a matrix for gold nanoparticles, the formation of various gold carbides Au_mC_n was detected and their stoichiometry was determined. It was demonstrated that TOF MS can be used advantageously to analyze NDs, characterize their size distribution, aggregation, presence of trace impurities and surface chemistry. Copyright © 2009 John Wiley & Sons, Ltd.     

Ultra-sensitive radionuclide spectrometry: Radiometrics and mass spectrometry synergy

Summary Recent developments in radiometrics and mass spectrometry techniques for ultra-sensitive analysis of radionuclides in the marine environment are reviewed. In the radiometrics sector the dominant development has been the utilization of large HPGe detectors in underground laboratories with anti-cosmic or anti-Compton shielding for the analysis of short and medium-lived radionuclides in the environment. In the mass spectrometry sector, applications of inductively coupled plasma mass spectrometry (ICP-MS) and accelerator mass spectrometry (AMS) for the analysis of long-lived radionuclides in the environment are the most important recent achievements. The recent developments do not only considerably decrease the detection limits for several radionuclides (up to several orders of magnitude), but they also enable to decrease sample volumes so that sampling, e.g., of the water column can be much easier and more effective. A comparison of radiometrics and mass spectrometry results for the analysis of radionuclides in the marine environment shows a reasonable agreement - within quoted uncertainties, for wide range of activities and different sample matrices analyzed.     

Tunable thermal lens spectrometry utilizing microchannel-assisted thermal lens spectrometry

A tunable thermal lens spectrometry system was developed for microchip analysis. The system utilized a Xe lamp as an excitation source, instead of a laser. The system can measure the absorption spectrum of a turbid solution without disturbance of the light scattering background.     

Electron impact ionization mass spectrometry and tandem mass spectrometry of phenylalkylpyridazines

The mass spectrometric fragmentation behaviour of pyridazine and four monosubstituted derivatives containing a pbenylalkyl side-chain (3- and 4-benizylpyridazine, 3- and 4-(2-pbenylethyl)pyridazine) was investigated. In the electron impact ionization mess spectra of the 3-substituted compounds abundant [M – H]⁺ peaks are observed. This allows a clear distinction between 3- and 4-substituted pyridazines, as the spectra of the latter isomers show only very weak [M – H]⁺ signals. The stability of [M – H]⁺ ions derived from 3-alkylpyridazines (deduced from only the very low abundance of further fragment ions) gives strong evidence for a cyclic structure of these ions. One fragmentation pathway typical of the parent pyridazine, the [M - N₂] fragmentation, was not detectable with any of the phenylalkylpyridazines investigated. Instead, loss of HCN, H₃CN⁺ and N²H⁺ was observed. An interesting fragmentation, observed with 3-(2-phenylethyl)pyridazine, is the loss of ⁺CH₃ from the molecular ion and also from the [M – H]⁺ ion.     

Electrospray mass spectrometry of

There has been a substantial growth in the application of mass spectrometry (MS) methods for the analysis of inorganic materials, due to the inherent sensitivity of mass spectrometry ionization to the specific composition and structure of the analyzed materials. To date, few mass spectrometry studies have focused on metal-chalcogenide materials, an important class of semiconductor materials at the nanoscale, that exhibit interesting optical and electronic properties as a function of size. In this study, we report the application of a correlated electrospray mass spectrometry (ESMS) study between negative-ion and positive-ion mode under low-cone voltage to probe size, composition, and stability of metal-chalcogenide materials at the <1 nm scale. This correlation approach provides insight into the ionization behavior and thermodynamic stability of clusters in the <1.0 nm size domain of the form [Zn4(SPh)10][Me4N]2, [Cd4(SPh)10][Me4N]2, [E4Zn10(SPh)16][Me4N]4, [E4Cd10(SPh)16][Me4N]4 (E = S, Se). It is demonstrated that application of low-cone voltage ESMS can be a useful technique for the rapid analysis of intact solid state nanomaterials when both negative and positive ionic modes are analyzed, with a potential for extrapolation to other classes of nanoscale materials.