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[en] Complete text of publication follows. Since early 1960's, the traditional 57Fe absorption variant of Moessbauer spectroscopy has been steadily applied in bioscience up to now, as iron is an essential trace element. As compared to this success, the emission (57Co) counterpart (EMS) has been suffering a general declining trend over the last couple of decades and, in particular, it has scarcely been in use in biology-related fields (see, e.g. Moessbauer Effect Ref. Data J., 30, No. 5 (2007) 90, 107-113, 116-122; A.A. Kamnev, J. Mol. Struct., 744-747 (2005) 161-167). While this is due to the methodological difficulty of using the 57Co radionuclide in samples, the game is worth the candles. First, the 57Co EMS sensitivity is up to 104-fold higher than that of the 57Fe absorption mode. Second, cobalt is a metal used by Nature, besides cobalamins (vitamin B12), in a number of metalloproteins and enzymes. Third, Co2+ can be used as an isostructural probe substituting for some biologically essential trace elements, e.g. Zn2+ in zinc proteins (see, e.g. M. Adamczyk et al., FEBS Lett., 581 (2007) 1409-1416 and references therein). Also, 57Co EMS can be successfully applied for monitoring 57Co2+ interactions with microbial cells and its metabolic transformations in live cells (A.A. Kamnev et al., Anal. Chim. Acta, 573-574 (2006) 445-452). Along with chemical speciation data for the 57Co cation (chemical state, bonding type and coordination symmetry, etc.) reflected by the parameters of 57Co emission spectra, EMS gives quantitative information on its distribution between different binding sites in complicated systems 'the pith and marrow' of trace speciation analysis. Besides solids, EMS measurements can be performed in rapidly frozen solutions, which is of importance for comparatively studying dissolved biocomplexes and their structure. It has to be noted that, in order to reliably interpret emission spectra of complicated 57Co-doped biosystems, much data on simpler biomolecules and model compounds have yet to be accumulated. The aforementioned capabilities of EMS will be illustrated in this talk using our recent studies ranging from 57Co-doped enzyme active sites to complexes with amino acids and microbial autoinducers (signalling molecules). This study was supported by NATO (Projects LST.NR.CLG 981092 and ESP.NR.NRCLG 982857) and under the Agreements between the Russian and Hungarian Academies of Sciences for 2005-2007 and 2008-2010.
[en] Complete text of publication follows. Direct methods of solid samples analysis and especially some mass spectrometric methods are intensively developing nowadays. These techniques have some important advantages over methods including preliminary solution of a sample. One of these fast developing methods of direct analysis of solid state samples is glow discharge mass-spectrometry. Direct current glow discharges and high resolution mass analyzer are used in most commercial glow discharge mass spectrometers. Recently the production of time-of-flight mass spectrometers with pulsed glow discharges was started (A. A. Ganeev et al., Journ. Anal. Chem. (Rus), 62 (2007) 494-504, A. A. Ganeev et al., Mass-spectrometry (Rus),3 (2006) 185-192, A. A. Ganeev et al., Mass-spectrometry (Rus), 6, 1, (2009) 67-76). Such spectrometers allow the analysis of both conductive and non-conductive samples. Besides, pulsed glow discharges allow to achieve high sputtering efficiency of sputtering and ionization of sample elements with weak heating. Some dynamic processes in pulsed discharge in combined hollow cathode used as source for analytical GD TOFMS are considered. The effect of the addition of hydrogen to glow discharge coupled to a time of flight mass spectrometer has been studied. Addition of hydrogen has shown the increase intensities of sample components and decrease intensities of discharge gas components. Reactions describing processes at presence of hydrogen are considered. Influence of pressure on discharge gas and dynamic of clusters transportation on intensities of clusters components was investigated for some types of clusters. Dynamic discrimination has allowed to increases number of determined elements due to essential reduction of interferences. One of important application of this process is determination of Ca in metallurgical Silicon. In this case 40Ca in metallurgical Silicon does not interfere with 40Ar because intensity of 40Ar is very low. The problem of quantification in glow discharge mass spectrometry is observed. Using RSFs (relative sensitivity factors) (A. A. Ganeev et al., Journ. Anal. Chem. (Rus), (2009) in press, A. A. Ganeev et al., Analytical and Bioanalytical Chemistry, (2009) in press) can to a great extent solve the problem. The possibilities of time-of-flight mass spectrometry with pulse glow discharge ionization in semi-quantitative analysis without using of standards samples are discussed.
[en] Complete text of publication follows. Present work describes determination of elemental composition of apatite crystals with the use of Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA ICP MS). Apatite is the most important representative mineral of phosphates with the most common formula written as Ca5(PO4)3OH. During the measurements the assumption was made about the content of 42.3 % P2O5 and 50.3-55.9 % CaO in the analyzed crystals. Apatite is one of few minerals that are produced and used by biological systems and it is the major component of the vertebrates' skeleton (above 60%) and tooth enamel (even 90%). A relatively rare form of apatite in which most of the OH groups are absent and containing many carbonate is a large component of bone material. In this work crystalline apatite was analyzed as models before archaeological bones measurements. The work was devoted to recognize the possibility of Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) as a method for direct measurement of bulk composition of apatite samples. LA ICP MS has been used widely to measure the chemical composition of small amounts of solid samples in many fields (e.g. environmental, geological, and archaeological sciences). The method does not require special sample preparation such as sample dissolution or even polishing. Therefore the method is very fast and gives large amount of information in the relatively short time. The method offers a spatial resolution from 10 to few hundred μm. Eight apatite crystals were analyzed. All crystals were divided into 3 pieces and analyzed by means of either LA ICP MS (using two different wavelengths if laser during ablation) or ICP MS after digestion. Analytical signals of LA ICP MS were for registered during one point or single line ablation mode, what delivered the information about the sample inhomogeneity. For the final analysis the amount of 11 independent repetitions of analysis were found to be required for obtaining the results comparable with ICP MS analysis. The authors kindly acknowledge the financial support from the Ministry of Science and High Education of Poland (No. N N204 241734).
[en] Complete text of publication follows. A wide variety of spectroscopic methods is used to solve very complex analytical tasks in research, development, production, and quality assurance. The subjects of study are often characterized by many interesting features. The features to be analyzed, very often have multidimensional characteristics interacting significantly with each other. Owing to this fact and the inhomogeneous distribution of analytes, analysis requires many samples and investigations of several features in parallel. Many of the wide range of spectroscopic methods are useful tools for multifeature analysis, i.e. multielement or multicomponent, respectively. Analysis of mixtures and measurements in the range of traces or even ultra traces are very important fields of research in spectroscopy. On the one hand, these characteristics offer an excellent opportunity to investigate complex systems. However, an enormous flood of complex information, which contains both high variability and high uncertainty to some extent, is generated. Additionally, due to economic and time constraints an analyst's aim is to measure as few features as possible in the minimum of samples. That means e.g. an efficient number of samples by means of optimized measurement procedures. All these issues require chemometric approaches, i.e. mathematical and statistical methods to design and to select optimal experimental/analytical procedures in order to gain maximum relevant information from the data. First, a short overview of methods and goals of chemometrics is presented. Then, useful methods of chemometrics used before spectroscopic measurements will be introduced. Here, the case study 'determining the uncertainty of sampling' will be discussed in detail. It was shown that variance of different steps of the analytical process can be resolved and, thus, can be estimated quantitatively by analysis of variance. Then, distinctive approaches of chemometrics in spectroscopy will be demonstrated and a case study of NIR spectroscopic analysis of starch in rye is discussed. It is demonstrated that the combined approach of NIR analysis and chemometric evaluation using PLS regression is much faster than any common enzymatic starch determination. Another very important field of work in chemometrics deals with the treatment, evaluation, and interpretation of spectroscopic data, i.e. its application after spectroscopy. An overview of the manifold approaches of multivariate data analysis ranging from methods of unsupervised learning over classification methods to factorial methods will be given. Selected methods of data analysis will be explained by case studies from the field of environmental research: evaluation and interpretation of river sediment data. Cluster analysis can be used clearly to detect the multivariate structure of the river course. Factor analysis helps uncover hidden origins of pollution, like dischargers or diffuse effluents. Finally, PLS regression enables the quantitative description of deposition-remobilisation processes between different compartments of a river.
[en] Complete text of publication follows. Lawton and Sylvestre, and later Borgen et al. provided first the analytical solution for determining feasible regions of self-modeling curve resolution (SMCR) method for two- and three-component systems, respectively. After twenty years, Rajko and Istvan recently revitalized Borgen's method given a clear interpretation and algorithm how to draw Borgen plots using computer geometry tools; later Rajko proved the existence of the natural duality in minimal constrained SMCR. In both latter cases, 1-norm was used to normalize raw data; however Borgen et al. introduced a more general class of normalization. Rajko, very recently, has given the definition and detailed descriptions of Borgen norms. Wang et al. proved that, using p-normalization (p ≥ 1) for two-way data, the vertex vectors (which will be the pure variables if they exist) maximize a certain quadratic form over all points on a simplex (p = 1) or a polyhedral hyper-'spherical' surface (p > 1) in a recent paper. Based on this theorem, they developed a procedure for determining pure(st) variables. Rajko and Faber could give a proof that vertex vectors sequential projection method is not general, i.e. it can not be considered as the generalization of the method of Jiang et al. Now, in this lecture applying Borgen norms, we give a proper generalization of the simplex-based method developed by Jiang et al., and we illustrate the procedure with spectroscopic data.
[en] Complete text of publication follows. Cloud Point Extraction (CPE) of organic and inorganic compounds using non-ionic surfactants have been concerned in analytical chemistry. The use of micellar systems as an alternative to other techniques of separation offers several advantages. When heating a surfactant solution over the critical temperature, the solution is easily separated into two distinct phases. The hydrophobic compounds, initially present in the solution and bound to the micelles, are extracted to the surfactant-rich phase. In this work, both traditional and on-line flow-injection cloud point extraction (FI-CPE) systems were used for flame atomic absorption spectrometric determination of iron. For CPE preconcentration, aliquots of 10 mL of solution or standard solution of iron, complexing agent Erio Chrome Cyanine R (ECR) (0.1% w/v), acetate buffer (pH=4.5) and 0.5 M NaCl were placed in a graduated centrifuge tube. The tube was shaken with vortex and stand for 5 minutes. Then, non-ionic surfactant TritonX-114 (10% v/v) was added. Again total solution was shaken with vortex. The tube was kept in a thermostated bath at 70 deg C for 15 minutes. In traditional CPE procedure, separation of the aqueous and surfactant-rich phases was accomplished with keeping tube for 5 minutes and easily just by pipeting. Later, in order to decrease the viscosity and facilitate sample handling, surfactant-rich phase diluted with acidic ethanol and introduce to nebulizer of Flame Atomic Absorption Spectrometer (F-AAS). CPE has been successfully adapted to online system by Flow Injection (FI) and with subsequent detection by F-AAS. After heating the tube at 70 deg C, the micellar solution loaded through a column packed with cotton, which acts as a filter for retaining the analyte-entrapped surfactant-rich phase. Then the surfactant-rich phase was eluted using acidic ethanol at a proper flow rate and directly introduced into the nebulizer of the FAAS. Several factors influencing the instrumental conditions and extraction were evaluated and optimized. Under the optimum conditions, the enhancement factors of the proposed methods, the detection limits, relative standard deviations were determined and the developed methods were successfully applied to the extraction and determination of the iron metal ions in certified and real samples and satisfactory results were obtained. Finally, analytical performances of the proposed traditional and on-line FI-CPE methods were compared.
[en] Complete text of publication follows. Solid phase extraction (SPE) preconcentration and separation coupled with flame atomic absorption spectrometry (FAAS) have shown to be powerful for determination of trace elements in a variety of matrices. The most simple SPE to be used in practice is based on sorption of metal ions as chelates and/or inorganic complexes. The broad variety of sorbents available explains one of the most powerful aspects of SPE, which is selectivity. However, still in trace element analysis, investigations for finding new materials as solid phase extractor are an important issue to preconcentrate heavy metals at trace level. In this regard, the anion exchange properties of polypyrrole doped-chloride(PPyCl), that is easily synthesized chemically, may be used to uptake anions or metal complexes in anionic form from aqueous solutions. These investigations encourage us to examine the efficiency of PPyCl as a sorbent for preconcentration of trace metal ions. This research thus focused on the use of PPyCl for a highly selective solid phase extraction and a novel procedure for preconcentration of Cu from complex sample matrices was developed for improving the detection limit of the determination by FAAS with microinjection. In the procedure, copper as Cu(II)-Pyrocatechol Violet(PV) chelate in anionic form was preconcentrated by a column filled PPyCl. All variables involved in the development of the preconcentration procedure including, pH, sample and eluent volume, sample and eluent flow rates, interfering effects, etc., were studied to achieve the best analytical performance. A recovery percentage higher than 95% was obtained in range of pH 4.0-6.0. A preconcentration factor of 40 was achieved with a final volume of 1.0 mL. The R.S.D. was 3.4%. The method was successfully applied to the determination of copper in various samples.
[en] Complete text of publication follows. Using magnetic nanoparticles for separation and preconcentration in analytical chemistry is opening a new methodology that is faster, simpler and more precise than old ones. In this work, a simple and reliable solid-phase extraction method has been developed to selectively separate and preconcentrate trace amounts of silver (I) from aqueous samples for subsequent measurement by atomic absorption spectrometry. Silver ion was adsorbed quantitatively from aqueous solution onto magnetic nano-adsorbent with dithizone (DTZ) immobilized on sodium dodecyl sulfate (SDS)-coated Fe3O4 nanoparticles (DTZ-S-IONPs). SDS as a surfactant makes admicelle on the surface of Fe3O4 nanoparticles, which allows the metal complexing agent of DTZ, to be immobilized in its hydrocarbon cores. This assemble, as a chelating adsorbent, has made the separation and preconcentration of silver ion possible. It is shown that the novel magnetic nano-adsorbent is quite efficient for the adsorption and desorption of silver (I) at 25 deg C. Different parameters such as pH, temperature, ionic strength, equilibrium time, type and least amount of stripping solution were optimized. The effect of some co-existing ions on the determination was investigated. An aqueous solution containing thiourea has been used in order to selectively desorb the adsorbed silver ion from the surface of the adsorbent. No serious interferences have been observed due to the presence of another species in the sample. The separation selectivity of the adsorbent for other cations was studied. To improve this, EDTA was added to the source solution before applying to the DTZ-S-IONPs as chelating adsorbent. The procedure was applied for analysis of two real samples. The method is simple and inexpensive. This research was supported by the Department of Chemistry and Nanoscience and Nanotechnology Research Laboratory (NNRL) Payame Noor University of Sirjan.
[en] Complete text of publication follows. In the last ten years, Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) has become one of the most suitable techniques for analyzing minor and trace elements in solids. A large number of successful applications in geosciences and material sciences have been demonstrated using various instrument configurations and precise and accurate results can be achieved. However, selected elements (Cd, Zn, Sn etc.) still suffer from being determined accurately by partially unknown sources of fractionation, which occur during the ablation process, the aerosol transport or within the ICP-MS itself. Therefore, the more non-thermal ablation process using fs-LA is considered to improve accuracy and is currently investigated in great detail. The presentation will highlight results achievable on selected applications using ns and fs-LA. The determination of Pb and U in zircons using non-matrix matched calibration will be discussed in great detail. Furthermore, superconducting materials will be reported and the results of UV-ns and UV-fs laser ablation will be compared. Most of the quantification approaches discussed in this presentation are based on the use of non-matrix matched calibration materials and it will be shown that the fs-LA improves the intern-matrix calibration capabilities (metal versus glass). However, some of the matrix effects observed for UV-ns LA still occur, but are reduced in the order of magnitude. Finally, an atmospheric sampling strategy for laser ablation-ICP-MS will be introduced.
[en] Complete text of publication follows. Since the discovery of neutron activation analysis (NAA) by Hevesy and Levi in 1936, a number of NAA methods have been developed for the determination of elements at trace levels in a variety of materials. The most common form of NAA is called instrumental NAA (INAA) which does not involve any pre- or post-irradiation chemical treatment. There are many advantages of INAA over other analytical techniques such as non-destructive analysis, freedom from reagent blanks, and simultaneous multielement specificity. One of the problems generally encountered in INAA is a high background activity arising from the scattering of photons; this phenomenon is called the Compton Effect. Better detection limits could be obtained if the Compton continuum is suppressed. We have developed several INAA methods in conjunction with anti-coincidence gamma-ray spectrometry for lowering the background activities as well as to minimize, if not completely eliminate, interferences. We have carried out a systematic study on the advantages of INAA using anti-coincidence (INAA-AC) gamma-ray spectroscopy. We have developed a technique called pseudo-cyclic INAA-AC (PC-INAA-AC) for the detection of short-lived nuclides (half-life <120 s) such as 108Ag, 110Ag, 165mDy, 20F, 75mGe, 179mHf, 86mRb, 46mSc, 77mSe, and 177mYb. Then we studied medium-lived nuclides (half-life <3 h), namely 28Al, 139Ba, 80Br, 38Cl, 66Cu, 165Dy, 128I, 27Mg, 56Mn, 65Ni, 233Th, 51Ti, and 52V using conventional INAA-AC. We used the same technique to investigate some long-lived nuclides (half-life >12.5 h) such as 76As, 198Au, 82Br, 141Ce, 51Cr, 60Co, 59Fe, 197Hg, 203Hg, 42K, 140La, 24Na, 147Nd, 86Rb, 122Sb, 46Sc, 182Ta, 160Tb, 187W, 175Yb, 69mZn, and 65Zn. Perhaps the most important advantage of INAA-AC is the considerable decrease of the background activity with no reduction of the peak area. The quantification of this advantage is rather difficult. We defined an analytical figure of merit (AFOM) term for assessing the practical advantages of anticoincidence counting. The details of experiments and results will be presented. The authors gratefully acknowledge the financial support from the Natural Sciences and Engineering Research Council of Canada.