Simultaneous determination of metallic elements in precipitates and inclusions extracted from steel by inductively coupled plasma-atomic emission spectrometry

A study was made about the possibility of extracting complex precipitates, containing carbides, nitrides, intermetallic compounds, from low-alloy steels, high-alloy steels and heat-resistant super alloys by single electrolysis operation, followed by the simultaneous determination of all metallic elements in the precipitates by inductively coupled plasma-atomic emission spectrometry (ICP-AES). As a result, it was found that 4–5 metallic elements, such as Nb, Mo and Cr, whose determination had been considered difficult even by wet chemical analysis, can be simultaneously determined in the dissolved state in which Na₂S₂O₇ and tartaric acid (20%) added for the treatment of precipitates are concomitants.ICP-AES simplifies the analytical operation considerably and shortens the analytical time from about 18 h by conventional methods to about 1 h.     

Behaviour of trace impurities during chemical dissolution of a metal: Platinum elements in aluminium and nickel

In order to study the behaviour of trace impurities during aqueous dissolution of a sample, aluminium and nickel-based alloys containing 10⁻⁴−1% Ir, Os or Ru were used. Yields of chemical separations such as distillation and ion-exchange were chosen as dissolution criteria. Dissolution of aluminium samples leads to precipitation of the three impurities. The Os and Ru precipitates can afterwards be dissolved by an oxidation procedure, in contrast to commercial powders of these elements. This behaviour may be explained in terms of the small grain-size of the precipitates. The indium precipitates cannot be dissolved, which prevents quantitative separation of this element from an aluminium matrix. In the case of nickel alloys, these three impurities are dissolved and can be quantitatively separated.     

Identification of chemical substances in analytical measurements

 Characteristic features of identification procedures of chemical substances are described and the metrological requirements for identification are discussed. The procedures are considered to be rigorous enough, if quantitative criteria such as the measure of similarity between physicochemical properties or spectra of the unknown substance and reference materials are used. Identification involves expert opinion which is of prime importance in the analysis of samples of unknown composition. The reliability of substance recognition can be increased by selecting highly qualified personnel, establishing a good information supply, using an on-line combination of separation and detection instruments such as chromatography-spectrometry and estimating the probability of identification. Standard conditions for reliable identification including quantitative criteria are examined using gas chromatography-mass spectrometry as an example. Received: 19 August 1998 / Accepted: 12 September 1998     

Recent developments in DNA adduct analysis using liquid chromatography coupled with mass spectrometry

The formation of DNA adducts by genotoxic agents is an early event in cancer development, and it may lead to gene mutations, thereby initiating tumor development. The measurement of DNA adducts can provide critical information about the genotoxic potential of a chemical and its mechanism of carcinogenesis. In recent decades, liquid chromatography coupled with mass spectrometry has become the most important technique for analyzing DNA adducts. The improvements in resolution achievable with new chromatographic separation techniques coupled with the high specificity and sensitivity and wide dynamic range of new mass spectrometry systems have been used for both qualitative and quantitative analyses of DNA adducts. This review discusses the challenges in qualitative and quantitative analyses of DNA adducts by liquid chromatography coupled with mass spectrometry and highlights recent developments towards overcoming the limitations of liquid chromatography coupled with mass spectrometry methods. The key steps and new solutions, such as sample preparation, mass spectrometry fragmentation, and method validation, are summarized. In addition, the fundamental principles and latest advances in DNA adductomic approaches are reviewed.     

Fundamentals of heterometry and their interpretation

Heterometry deals with the photometric study of chemical reactions in suspensions on a quantitative basis. While a linear relation between the quantity of material and the light absorption is the basic condition in “turbidimetry”, this situation is not generally observed in heterometry. No protective colloids are used in heterometry. The heterometric study of a chemical reaction is generally combined with parallel conductometric and pH-titrations. Parallel pH and heterometric titrations are essential for procuring detailed information about the pH-conditions for the formation and dissolution of precipitates.     

Identification of polyimide materials using quantitative CE with UV and QTOF‐MS detection

Polyimides (PIs) are a group of widely used synthetic materials that service a variety of different purposes including microelectronics, insulating films and aerospace applications. Depending on the requirements (defined by the particular final product), the actual composition of PIs may show substantial chemical variation. To study this variation in chemical structure, CE‐MS can be employed for the determination of PI composition following chemical degradation of the polymer sample. PI is chemically decomposed to corresponding aromatic diamine and carboxylic acid components using an alkali fusion reaction. Solid polymer samples are fused in a potassium hydroxide melt yielding reaction products that are diluted in acid and can be immediately analysed by CE coupled to a Q/TOF‐MS with quantification performed using conventional UV detection. This approach involves a simple and rapid sample preparation yielding both qualitative and quantitative information regarding the chemical composition of the polymer. Application of the CE‐MS approach is shown for a range of commercially available PI and poly(amide–imide) materials and the results are used to infer the respective chemical compositions.     

Quantitative Analysis of Thin Aluminium-Oxynitride Films by EPMA

 Thin films of aluminium oxynitride with diverse composition were prepared by dc-magnetron sputtering of aluminium, utilising sputtering power as well as argon, oxygen and nitrogen gas flows to vary the composition. Since film properties depend mainly on the content of incorporated oxygen and nitrogen, a method for quantitative analysis of the main constituents based on electron probe micro analysis with energy dispersive detection was developed. The excellent precision of the quantitative results for aluminium as well as oxygen and nitrogen are shown. Furthermore, a film layer analysis program was applied for the quantification of several films deposited under the same deposition parameters on silicon wafers, from 520 nm down to 40 nm thickness, showing that electron probe micro analysis with energy dispersive detection is a reliable method for quantitative compositional analysis of thin aluminium oxynitride films down to approximately 20 nm thickness. Since this method of analysis provides only bulk information, expected inhomogeneities of the depth distribution of the film components were checked by secondary ion mass spectrometry depth profiles of two thin films and correlated to the EPMA results. The thickness of the films was determined by ellipsometry. Received September 1, 1998     

Qualitative and quantitative analysis of enantiomers by mass spectrometry: Application of a simple chiral chloride probe via rapid in-situ reaction

A tandem mass spectrometry method for high-sensitivity qualitative and quantitative discrimination of chiral amino compounds is conducted. The method is based on a chemical derivation process that uses a simple reagent, L-1-(phenylsulfonyl)pyrrolidine-carbonyl chloride, as the probe. The method is applicable in both organic solutions and biological conditions. Twenty-one pairs of enantiomer containing amino acids, amino alcohols, and amines are used to produce diastereomers using the probe via in situ reaction for 20 s at room temperature. The resulting diastereomers are successfully recognized based on the relative peak intensities of their fragments in positive mode, with the chiral recognition ability values ranging from 0.35 to 3.83. The L/D ratio of Pro spiked at different concentrations (enantiomeric excess) in both acetonitrile and dog plasma is determined by establishing calibration curves. This method achieves a lower limit of quantification of 50 pmol in analyzing amino acids using an extract ion chromatograph. The relative standard deviation for both qualitative and quantitative results is <5%. Thus, the present method is demonstrated as a new and practical technique of rapidly and sensitively determining enantiomers of amino compounds.     

Chemical analysis of thin films by means of SS-MS, GD-OES, and XPS demonstrated at Ir-Si thermoelectrica

Analytical methods with low detection limits were used for the investigation of Ir-Si thin films, the physical properties of which vary strongly with the chemical composition and the amount of impurities. It is demonstrated how to solve chemical characterization of different thermoelectric Ir-Si thin films by spark source mass spectrometry (SS-MS), glow discharge optical emission spectroscopy (GD-OES) and X-ray photoelectron spectroscopy (XPS). The combined use of the three different facilities allows the quantification of impurities of elements of the entire periodic system in the ppm range (down to 30 at.-ppm in dependence on the element) incorporated in thin film samples. Additional information about the in-depth distribution of elements or specifically bonded species can be achieved with a high depth resolution. Received: 6 April 1998 / Revised: 9 July 1998 / Accepted: 14 July 1998     

Determination of Heavy Metals in Soils, Sediments and Geological Materials by ICP-AES and ICP-MS

 Sixteen soil and sedimentary geological reference materials were analysed for As and the heavy metals Cd, Co, Cr, Cu, Ni, Pb and Zn by inductively coupled plasma-atomic emission spectrometry (ICP-AES) and inductively coupled plasma-mass spectrometry (ICP-MS) in combination with total and partial dissolution of the samples. It can be demonstrated that none of the modern ICP methods is completely free from analytical problems. This applies in particular when the concentrations are close to the detection limits (e.g. in ICP-AES) and is mainly due to the wide variation in the bulk composition of soils resulting in complex matrix effects (e.g. in ICP-MS). In order to determine the extent of soil pollution by heavy metals, both partial and total dissolution have to be performed prior to analysis.     

Natural resonance theory: III. Chemical applications

We describe quantitative numerical applications of the natural resonance theory (NRT) to a variety of chemical bonding types, in order to demonstrate the generality and practicality of the method for a wide range of chemical systems. Illustrative applications are presented for (1) benzene and polycyclic aromatics; (2) CO₂, formate, and related acyclic species; (3) ionic and polar compounds; (4) coordinate covalent compounds and complexes; (5) hypervalent and electron-deficient species; (6) noncovalent H-bonded complex; and (7) a model Diels-Alder chemical reaction surface. The examples exhibit the general harmony of NRT weightings with qualitative resonance-theoretic concepts and illustrate how these concepts can be extended to many new types of chemical phenomena at a quanitative ab initio level. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 628–646, 1998     

A complete fluorine-19 NMR characterization of a commercial grade sample of perfluorohexanes

The complete qualitative and quantitative chemical characterization of a complex, commercial grade sample of ‘perfluorohexanes’ has been accomplished with the use of a single instrumental analytical method: fluorine-19 nuclear magnetic resonance (F-nmr) spectroscopy. With the combination of routine one dimensional (ID) and two dimensional (2D) F-nmr data acquisition techniques, the commercial grade sample was found to be composed of all five acyclic perfluorohexane isomers and two cyclic perfluorinated alkanes. The F-nmr spectra yielded information about chemical shifts, spin-spin fluorine-fluorine (F-F) coupling constants, and relative intensities for fluorine nuclei in all components. The qualitative and quantitative specificity of the F-nmr analysis method circumvented the need to use other instrumental analytical methods for composition evaluations.     

Application of XPS and ToF-SIMS for surface chemical analysis of DNA microarrays and their substrates

The chemical composition of the functional surfaces of substrates used for microarrays is one of the important parameters that determine the quality of a microarray experiment. In addition to the commonly used contact angle measurements to determine the wettability of functionalized supports, X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) are more specific methods to elucidate details about the chemical surface constitution. XPS yields information about the atomic composition of the surface, whereas from ToF-SIMS, information on the molecular species on the surface can be concluded. Applied on printed DNA microarrays, both techniques provide impressive chemical images down to the micrometer scale and can be utilized for label-free spot detection and characterization. Detailed information about the chemical constitution of single spots of microarrays can be obtained by high-resolution XPS imaging. Figure Eye-catching image for the graphical online abstract     

Determination of molybdenum in steels by flow-injection spectrophometry

A flow-injection procedure is proposed for the determination of molybdenum in steels based on the thiocyanate method. Effects of iron(III), acidity, reagent concentration and interfering species were investigated by using flow-injection systems with the merging zones approach which reduced drastically the number of standard solutions to be prepared. Full details of system design are given. The procedure can be applied to several types of steel samples of industrial relevance. After dissolution of the steels in aqua regia, molybdenum can be determined in the range 0.10–4.00% (w/w) at a rate of up to 270 samples per hour with relative standard deviations less than 2%. The results agree with those obtained by atomic absorption spectrometry with the standard addition method and by plasma atomic emission spectrometry, and with certified values of standard reference samples.     

Surface-analytical studies on environmental and geochemical surface processes.

The surface chemical compositions of solid samples from environmental and geological sources can differ from the bulk or average compositions, because of changes caused by adsorption, dissolution, oxidation, etc. Accordingly, analytical information on surface layers is important for a better understanding of the environmental chemistry involving solid surfaces. The rapid development of surface-analytical techniques has enabled us to probe the surface chemistry of environmental and geological solid samples of complex composition. This article demonstrates some examples of important items of information that can be obtained by applying surface-analytical techniques, such as X-ray photoelectron spectroscopy and secondary ion mass spectrometry, to environmental and geological samples. The surface analysis of fly ashes, soils, sediments and weathered silicate minerals is reviewed.     

Elucidating chemical reactivity by pattern recognition methods

Methods have been developed that allow important chemical effects to be quantified. Parameters calculated with these procedures can be used to investigate both quantitative and qualitative information on chemical reactivity. A variety of statistical and pattern recognition methods is used for that purpose. These studies lead to reactivity functions that allow the prediction of the course of complex organic reactions.     

Determination of the volatile chemical constituents of Notoptergium incium by gas chromatography-mass spectrometry and iterative or non-iterative chemometrics resolution methods

The qualitative and quantitative determination of the chemical constitutes in traditional Chinese medicine (TCM) is an important task, which builds the foundation of the theory of pharmacological activity. The hyphenated chromatography instruments combined with the related chemometric methods provide powerful tools for the resolution of such complex systems. The familiar chemometrics methods can be roughly divided into two different kinds, the iterative one such as orthogonal projection approach (OPA) and non-iterative one representing by evolving window orthogonal projection (EWOP). One can use different kinds of methods according to overlapping condition, and then the measured data matrix can be resolved into pure concentration profiles and mass spectra of the chemical components with relative high efficiency and acceptable accuracy. One kind of TCM, named Notoptergium incium (NI) was analyzed by gas chromatography-mass spectrometry (GC-MS) and resolved by above chemometric approach. Experiment results show the efficiency and convenience of the proposed approach. 65 of the 98 separated constituents in essential oil, accounting for 92.13%, were identified by mass spectroscopy (MS).     

Organic mass spectrometry at the beginning of the 21st century

Mass spectrometry in the last 15–20 years has become one of the first methods of the qualitative analysis and quantitative determination of various substances, from isotopes of chemical elements to synthetic polymers, proteins, and nucleic acids. This method allows analysts to work with both individual compounds and most complex mixtures that contain hundreds and thousands of compounds. It is the best in terms of the sensitivity, information content, and rapidity. This review covers the present-day achievements of mass spectrometry, including ionization and ion separation methods and different versions of its application in various fields of science and human activity.     

A new concept for the bioeffects-related analysis of xenoestrogens: Hyphenation of receptor assays with LC-MS

The wide variety of known and unknown endocrine disruptors demands highly efficient methods for detecting the relevant endocrine disrupting pollutants. Bioeffects-related analysis is expected to solve this problem, combining biomolecular recognition processes with chemical analysis, which therefore reduces costs of instrumental chemical analysis to relevant samples. The hyphenation of both steps provides information on potential bioeffects, structure and concentration of the substances of interest. In this work the hyphenation of an enzyme-linked receptor assay (ELRA) with liquid chromatography-tandem mass spectrometry (LC-MSMS) for the analysis of estrogens and xenoestrogens is proposed. Both test systems have been validated with standards and spiked real water samples. The ELRA achieved a detection limit of 0.1 μg/L for 17β-estradiol (without preconcentration). With the LC-MSMS method, steroids could be detected down to 1 ng/L (with preconcentration). Two concepts for a tighter hyphenation of biomolecular interaction and chemical analysis are discussed: the on-line coupling of receptor-affinity chromatography (RAC) to LC-MSMS and the direct measurement of receptor-ligand complexes by LC-MSMS. Received: 30 October 1998 / Revised: 18 December 1998 / Accepted: 26 December 1998