Analytical Spectrometry Research Articles

Editorial for European Symposium on Analytical Spectrometry and Czech-Slovak Spectroscopic Conference

Editorial for European Symposium on Analytical Spectrometry and Czech-Slovak Spectroscopic Conference

Editorial

This special issue of the Journal of Chemometrics is devoted to Dr. Steven D. Brown, who retired in 2021. Steve is one of the original leaders of the chemometrics revolution and one of the three founding editors of the Journal of Chemometrics. Steve has also served as one of the three editors in chief of the four-volume series, Comprehensive Chemometrics, published by Elsevier. Steve is the first recipient of the Eastern Analytical Symposium Award in Chemometrics. Steve has also taught the short course on chemometrics at National American Chemical Society meetings for 15 years and has been a member of the International Union of Pure and Applied Chemistry Working Group on Chemometrics since 1987 and the Chemometrics in Analytical Chemistry Program Committee since 1992. Steve has been an active participant at many historic chemometrics conferences, for example, the North American Treaty Organization Advanced Studies Institute on Chemometrics (Cosenza, Italy 1983), Snowbird Conference on Computer-Enhanced Analytical Spectrometry (1994), and International Chemometrics InterNet Conference Computer Network Conference on Chemometrics (1994). Steve has also served as an external referee on promotion and tenure committees for faculty in chemometrics (e.g., Paul Gemperline, Karl Booksh, Sarah Rutan, Barry Lavine, Paul Crilly, William Rayens, Sharon Neal, Peter Wentzel, Peter Harrington, Piet Van Espen, Paul Geladi, Frank Vogt, Rasmus Bro, and Jan Baumbach). Steven Brown obtained his PhD in analytical chemistry from the University of Washington in 1978, working in the laboratory of Bruce Kowalski. The title of his doctoral dissertation was “Computer-Controlled Electrochemistry and Pattern Recognition.” In 1978, Steve joined the faculty of the University of California at Berkeley as an assistant professor and as a principal investigator at the Lawrence Berkeley Laboratory. He moved to Washington State University in 1981 where he was awarded tenure and promoted to associate professor. In 1986, Steve joined the Department of Chemistry at the University of Delaware, advancing through the ranks to become a professor, chairman of the Department of Chemistry, and Willis F. Harrington Professor. Over the course of his career, Steve has published over 120 research papers and 22 book chapters and has presented 300 talks at seminars and professional meetings. Steve is best known for his work in Kalman filtering for peak deconvolution, calibration transfer between spectrometers without the need of standards, feedforward and Bayes neural networks for multivariate calibration and classification, wavelets, and more recently, imputation methods and stacked methods for classification and calibration of spectral data. Steve's work highlights the changes that have occurred in the field of chemometrics since its inception in the mid-1970s. Steven Brown is also regarded as an outstanding teacher. Many students who have taken Steve's courses over the years have commented that he explains the material well and his lectures are always thoughtful and well organized. As a thesis and dissertation advisor (31 master's and doctorate students), Steve is regarded as thorough, logical, and clear in his recommendations to guide students in their research. He is always available when needed to address questions and is a good critical reviewer of a student's work. On a personal level, Steve is thoughtful and soft spoken both with his undergraduates and with his graduate students—a true gentleman and scholar. Steve's sense of humor is disarming. From a professional standpoint, Steven Brown and Edmund Malinowski are similar in their accomplishments and their professional relations toward others, and it is appropriate that Steven Brown shares this special issue of the Journal of Chemometrics with Edmund Malinowski. Both pioneers possessed a wealth of knowledge and experience, and their retirement (Steve Brown) or death (Edmund Malinowski) signifies the end of an era for the community. The peer review history for this article is available at https://publons.com/publon/10.1002/cem.3470. No data is available.

ИЗМЕНЧИВОСТЬ КОНЦЕНТРАЦИИ КАДМИЯ И СВИНЦА В ВОДЕ КРУПНОЙ РАВНИННОЙ РЕКИ ЗА 30-ЛЕТНИЙ ПЕРИОД НАБЛЮДЕНИЙ

The article presents new analytical data on the content of cadmium and lead in river water obtained by the authors using highly sensitive specialized methods of analytical spectrometry. For the first time, a more than thirty-year (1983-2018) study has been carried out, tracing the concentration of elements in the mid-stream water of the Oka River in the area of Prioksko-Terrasny Biosphere Reserve (PTBZ) - a location remote from the zone of formation of technogenic dispersion flow. The general trend was found to be characterized by a gradual decrease in metal content, correlating with the implementation of various environmental measures in the river basin. The trend of decreasing concentration is well expressed for cadmium from 1983 to 1991 and is weaker from 1992 to 2018. Estimates are made of the average regional anthropogenic-dependent concentrations of elements in the Oka River waters, exceeding the Clark (background) values for the world’s rivers significantly. It can be predicted that, if this trend persists, cadmium concentrations in the water of a large plain river will approach the background values for surface waters of the Russian plain.

Flowing Atmospheric Pressure Afterglow for Ambient Ionization: Reaction Pathways Revealed by Modeling.

We describe the plasma chemistry in a helium flowing atmospheric pressure afterglow (FAPA) used for analytical spectrometry, by means of a quasi-one-dimensional (1D) plasma chemical kinetics model. We study the effect of typical impurities present in the feed gas, as well as the afterglow in ambient humid air. The model provides the species density profiles in the discharge and afterglow regions and the chemical pathways. We demonstrate that H, N, and O atoms are formed in the discharge region, while the dominant reactive neutral species in the afterglow are O3 and NO. He* and He2* are responsible for Penning ionization of O2, N2, H2O, H2, and N, and especially O and H atoms. Besides, He2+ also contributes to ionization of N2, O2, H2O, and O through charge transfer reactions. From the pool of ions created in the discharge, NO+ and (H2O)3H+ are the dominant ions in the afterglow. Moreover, negatively charged clusters, such as NO3H2O- and NO2H2O-, are formed and their pathway is discussed as well. Our model predictions are in line with earlier observations in the literature about the important reagent ions and provide a comprehensive overview of the underlying pathways. The model explains in detail why helium provides a high analytical sensitivity because of high reagent ion formation by both Penning ionization and charge transfer. Such insights are very valuable for improving the analytical performance of this (and other) ambient desorption/ionization source(s).

A LIPOSOMAL COMPOSITION OF MUSC DEER PREPUTIAL GLAND EXTRACT AS A NEW AGENT OF ADAPTOGENIC ACTION

For the first time, a liposomal form of a new original drug based on the Siberian musk deer preputial gland extract was obtained and characterized. An effective and scalable method of high-pressure homogenization was used for preparative extraction of liposomes from musk extracts. For the obtained liposomal product, such indicators as the quality of size distribution, homogeneity and the degree of inclusion of biologically active components were characterized using the methods of dynamic light scattering, transmission microscopy, preparative and analytical chromatography and chromatography-mass spectrometry. A homogeneous dispersion of musk liposomes with a uniform size distribution was obtained, with the maximum distribution values being achieved at 50 and 240 nm. The ζ-potential of the obtained nanoparticles of –35...–47 mV confirmed a high physicochemical stability of the developed liposomal dispersion. According to the gel filtration chromatography and mass spectrometry results, the degree of inclusion of the target musk extract components in the liposomes was 55–75% in terms of steroid and total protein values. The obtained quality indicators indicate that the developed liposomal composition of musk deer extracts can be used as a high-effective natural adaptogen.

Trace analysis of butyltin compounds in seawater of some west Algerian harbors by gas chromatography-mass spectrometry

ABSTRACTAn analytical gas chromatography-mass spectrometry (GC-MS) method was investigated for the determination of trace butyltin compounds (BTs) (tributyltin [TBT] and its derivatives dibutyltin [DBT] and monobutyltin [MBT]) in seawater collected from some west Algerian harbors. BTs were detected in all samples from all investigated sites. Levels of total BT concentrations detected in seawater ranged from 0.045 to 0.798 μg Sn L−1. Higher concentrations of BTs were found in seawater collected from Bethioua (0.798 μg Sn L−1), an oil terminal, and Mers El Kébir shipyard (0,585 μg Sn L−1). This suggested that maritime activities close to the harbors play a major role as the source of BTs. Indeed, the harbor of Bethioua is frequented by many tankers. TBT was the predominant compound in seawater collected from almost all the sampling locations, indicating the fresh input of TBT in the harbors.

Three-dimensional time-dependent computer modeling of the electrothermal atomizers for analytical spectrometry

A full three-dimensional nonstationary numerical model of graphite electrothermal atomizers of various types is developed. The model is based on solution of a heat equation within solid walls of the atomizer with a radiative heat transfer and numerical solution of a full set of Navier–Stokes equations with an energy equation for a gas. Governing equations for the behavior of a discrete phase, i.e., atomic particles suspended in a gas (including gas-phase processes of evaporation and condensation), are derived from the formal equations molecular kinetics by numerical solution of the Hertz–Langmuir equation. The following atomizers test the model: a Varian standard heated electrothermal vaporizer (ETV), a Perkin Elmer standard THGA transversely heated graphite tube with integrated platform (THGA), and the original double-stage tube-helix atomizer (DSTHA). The experimental verification of computer calculations is carried out by a method of shadow spectral visualization of the spatial distributions of atomic and molecular vapors in an analytical space of an atomizer.

Guest editor's introduction to the special issue on analytical spectrometry in China

Guest editor's introduction to the special issue on analytical spectrometry in China

Factors affecting the formation of the radiation pre-peak at the operation of a Grimm-type source in pulsed DC mode.

The plasma emission pre-peaks of many atomic and ionic spectral lines of Cu and Ar were systematically investigated in a Grimm-type pulsed glow discharge (PGD). To register the pre-peaks with sufficient time resolution, a monochromator with photomultiplier detection was used. When the applied power exceeded a specific threshold, pre-peaks were found in all spectral lines investigated, and it was revealed that the electrical pre-peak was the cause of the atomic emission pre-peak. The form and intensity of the pre-peak radiation were, however, found to be different for different atomic emission lines. The excitation energy of the upper energy level of the atomic line transition, and factors related to recombination and self-absorption, were found to affect the emission pre-peak. Pre-peaks observed when using pulsed DC and pulsed radio-frequency power were compared. This investigation provides insight into best practice when selecting spectral lines most suitable for analytical spectrometry using PGD.

Electronic stopping force of 12C, 28Si and 63Cu ions in HfO2 and SiO2 dielectric films

The stopping force of ions in matter is a basic physical concept that provides insight into the nature of ion-beam matter interactions. In applied research such as in nuclear analytical spectrometry the accuracy of stopping force data is crucial to the accuracy of analyses performed. The availability of ab initio calculations that can provide stopping force data with reasonable accuracy is a desirable development not only for ion beam analysis work and other applications that exploit the passage of energetic ions through matter, but also for fundamental ion-beam matter interaction studies. In this work stopping force measurements of 12C, 28Si and 63Cu ions through SiO2 and HfO2 dielectric films were carried out by time of flight spectrometry and the results are compared with semi-empirical calculations by Ziegler’s Stopping and Range of Ions in Matter (SRIM) code, and ab initio calculations by Grande and Schiewietz’s Convolution approximation for swift Particles (CasP) code. Indications are that in the 0.1–1.0MeV/u projectile energy range, while SRIM performs quite well for lighter ions, in the case of intermediate to heavy projectiles CasP is on par with, and promises to describe stopping more accurately than SRIM, possibly due to the former’s incorporation of charge exchange effects into total stopping.

Numerical modelling of thermal and gas-dynamic processes in a two-stage atomizer for analytical spectrometry

Based on a numerical solution of the Navier–Stokes equations and the equations of molecular kinetics, a complete computer model of a two-stage atomizer has been developed for analytical spectrometry, consisting of a graphite crucible evaporator and a helical atomizer. The model correctly takes into account the heating of the atomizer by an electric current, the gas dynamics, and nonsteady-state thermal-exchange processes, as well as the evaporation and condensation of the atoms of the test substance. The developed model has been experimentally tested, and the results of the modelling agree well with the experimental data.

Diethyldithiophosphate (DDTP): A Review on Properties, General Applications, and Use in Analytical Spectrometry

: The compound O,O-diethyldithiophosphate, also known as diethyldithiophosphate or DDTP, is employed in a variety of applications, from organic synthesis to extraction/separation of metals in preconcentration procedures. This reagent gained importance especially after preliminary investigations dated from the 1960s, which demonstrated its high stability in acidic medium and high selectivity and efficiency in complex formation reactions with metals and metalloids. The presence of two sulfur atoms and one phosphorus atom in the DDTP molecule turns this bidentate ligand into a versatile chelating agent, allowing the formation of complexes with a number of different geometric arrangements. In addition to the fact that the synthesis of DDTP is simpler in comparison to those of other dithiophosphates, it possesses other advantageous characteristics such as relatively low toxicity, high solubility in aqueous medium, high extraction efficiency from organic to aqueous media, and high redox potential. This review will summarize the main characteristics of DDTP, including some historical facts and information on its synthesis, structure, and toxicity, as well as other characteristics and numerous application examples. Special attention will be given to the reported analytical methods that use DDTP as a complexing agent in preconcentration procedures prior to analyte determination using spectrometric techniques.

Studies on archaeological gold items found in Romanian territory using X-Ray-based analytical spectrometry

This paper is an overview of the work developed by our group in the investigations of museum objects and alluvial gold, reflected in a series of studies published between 2000–2011, supplemented with new results, unpublished up-to-date. The X-ray based spectrometric techniques employed range from various X-Ray Fluorescence (XRF) investigations to ion beam analysis, including synchrotron radiation XRF and micro-Particle Induced X-ray Emission. The gold objects discussed are mainly part of the Sarmizegetusa Dacian hoards—spiraled bracelets (armbands) and coins. After obtaining in 2011 the permission of the Romanian authorities to take very small (1–2 mg) samples from the most “unimportant” areas of the Dacian bracelets and several Koson staters, to analyze them by micro-SR-XRF at BESSY, in February 2012, the investigation of several micro-areas of 17 stater and 28 bracelet samples revealed important micro-structural inhomogeneity, especially in Sn and Cu. The same inhomogeneous micro-structure has been seen in Transylvanian alluvial gold. The analyses revealed details on the fingerprint of geological gold deposits and also the main characteristics of ancient gold metallurgy procedures used by the Dacians: a relatively low temperature (lower than Au melting point) and hammering during heating to obtain an ingot through sintering. The use of the sintering procedure was proved for the spiraled bracelets and the Koson without monogram coins, a tradition starting in the Bronze Age in Transylvanian gold processing. The existence of micro-inclusions of Ta-minerals in alluvial gold was also detected, explaining Ta trace presence in the artifacts from the Pietroasa hoard.

A digitally controlled rotating field plasma source for analytical spectrometry

A highly flexible technology for constructing plasma sources based on the rotating field concept and the digitally controlled modulation of plasma heating is presented with the plasma source operating at audio and ultrasonic frequency adjustable in the 6–100 kHz range and powered in the 50–250 W range. The device allows for the production of non-stationary plasma discharge sustained by a rotating electric field produced within 5 electrodes positioned in the plane around the axis, while the plasma is temporarily stretched between at least two electrodes. A stable symmetrical low-flow helium discharge is formed at atmospheric pressure operating at total gas consumption of 100–1500 mL min−1 and it is self-igniting. The plasma fundamental parameters can be easily controlled in the wide range including He excitation temperature, OH rotational temperature and electron number density between 2200 and 3300 K, 850 and 1600 K, and 0.6 and 2.0 × 1014 cm−3, respectively. Therefore, the excitation power of the source may be controlled by variations of the pulse width, frequency, commutation mode and gas flow rate. The device is shown to be useful for atomic emission spectrometric determination of hydride forming elements and mercury at the ng mL−1 level. The excess of hydrogen produced in the hydride generation process can be tolerated by the helium plasma. Also, the plasma can be stably operated with argon, air and nitrogen.

Oxidation state sensitivity of Eu Lγ4 emission and its applications to oxidation state selective EXAFS spectroscopy of EuPd2Si2

In this paper, we have examined analytical spectrometry using Eu Lγ4. The oxidation-state-fluctuating compound EuPd2Si2 exhibits the largest temperature-induced valence changes among all Eu systems and does not have a structural phase transition below 298 K; EuPd2Si2 has a precipitous valence transition near 150 K. Hence, high-resolution EuLγ4emission spectra of EuPd2Si2 at 298 K and 30 K were measured using a multicrystal multidetector spectrometer. The spectra exhibited substantial differences, thereby indicating that the spectral shapes of Eu Lγ4 emissions depend on the oxidation state of the Eu ions. We have also demonstrated the applicability of Eu Lγ4 emission to oxidation state selective extended X-ray absorption fine structure (EXAFS) spectroscopy through partial fluorescence yield measurements with an excitation energy range of approximately 0.5 keV. In this manner, we have addressed and resolved two key questions in analytical spectrometry using EuLγ4.

Theoretical Characterization of an Atmospheric Pressure Glow Discharge Used for Analytical Spectrometry

We have investigated the plasma processes in an atmospheric pressure glow discharge (APGD) in He used for analytical spectrometry by means of fluid and Monte Carlo (MC) simulations. Typical results include the potential and electric field distributions in the plasma, the density profiles of the various plasma species throughout the discharge, the mean electron energy, as well as the rates of the various collision processes in the plasma, and the relative importance of the different production and loss rates for the various species. The similarities and differences with low-pressure glow discharges are discussed. The main differences are a very small cathode dark space region and a large positive column as well as the dominant role of molecular ions. Some characteristic features of the APGD, such as the occurrence of the different spatial zones in the discharge, are illustrated, with links to experimental observations.

Effect of a solvent on the parameters of the analytical signal, detection limit, and analytical range of the determination in analytical thermal lens spectrometry

The effect of the main parameters of the solvents (water, acetone, methanol, ethanol, acetonitrile, dimethyl sulfoxide, dichloromethane, toluene, and chloroform) that are most frequently used in the analytical practice on the characteristics of the thermal lens effect (increase in temperature because of optical heating and in the size of the region involved in heating) and on the detection limit and the lower determination limit of the thermal lens determination was considered, and the criteria of the selection of the medium for thermal lens experiments were discussed. It was demonstrated that the gain in these characteristics of the thermal lens determination in the given medium in comparison with the aqueous medium does not necessarily coincide with the strength of the thermooptical effect in this medium. It was demonstrated that the optimum conditions of measurements in the thermal lens detection are controlled not only by the absorption of the analyte and the reagents, but also by the intrinsic absorption of the solvent. Recommendations were given on the selection of the solvent for analytical thermal lens spectrometry.

Analytical laser ionization spectrometry in flame: Choice of the analytical form for the determination of rare earth elements

Based on the ionization potentials and dissociation energies of rare earth monoxides, these molecules are classified into two groups. For the molecules of the first type, the ionization potential is lower than the dissociation energy. Laser excitation of these molecules leads to their predominant ionization. For the molecules of the second type, the ionization potential is higher than the dissociation energy. Depending on the absolute values of the latter, atomic lines can be observed in the ionization spectrum. The elements that form molecules of the first type in flame should be determined as monoxide molecules. For the elements forming molecules of the second type, determination in the atomic form gives better results.

Modeling study on the influence of the pressure on a dielectric barrier discharge microplasma

In this paper we present a one-dimensional fluid model to study the properties of very small dielectric barrier discharges (DBD), which can be used as microchip plasma sources for analytical spectrometry. The influence of the pressure on this kind of discharge was investigated to obtain more insight in the variations of discharge current and the differences in particle densities that arise when operating at different pressures. The studied discharge gas is helium and is described with passive He background atoms, He+ and He2+ ions, He metastable atoms, higher excited states of He, He2* excimers and electrons. We show that the plasma activity, expressed in discharge current, is remarkably higher for pressures ranging from 50 to 140 mbar. For most pressures the calculated maximum current density is about 0.1 A cm−2, whereas in the range from 50 to 140 mbar the maximum current density is about 0.3 A cm−2. We also report how the plasma densities alter at different operating pressures, with spatially averaged densities at maximum current ranging from about 1016 m−3 to 1018 m−3, depending on the plasma species, and identify the main underlying processes, which are responsible for these evolutions.

Multielement analytical spectrometry as a data source for correlative classification of samples

Fast increase of correlations between the concentrations of elements is observed when diversity of the sample sources decreases. Data of high resolution sector eld ICP MS (inductively coupled plasma mass spectrometry) measurements of concentrations of 25 elements in wines were tested in the present study. As much as about ten or more pairs of correlating elements (correlation coefcient r > 0.9) were found for different wines of similar provenance. Correlation pattern is batch and sample specic. It represents the similar sources of elements, similar element quantity governing processes. If the number of the correlating pairs of elements is large, the mean within this list correlation coefcient can be calculated for individual samples, relative to the values of concentrations characteristic of different batches, and it can be used for identication of samples. Data on good potential for applicability of such individual sample-specic correlative characteristics in testing the provenance of samples are presented as examples.