On the perfection and application of the ‘scintillation method’ for spectral analysis of disperse substances

The principles of the “scintillation method” of spectral analysis are described. The method is based on the registration of a spectral-line flash intensity and its variation with time while a disperse substance is introduced into an excitation source. A comparative estimate of the precision of this type of analysis is given and results are presented of the determination of gold in standard reference material with a chemical composition of ores and rocks. The possibilities and application of the method to the analysis of disperse substances are considered.     

Surface phase analysis of catalysts and other disperse materials using electroconductivity: The TVE-curves method

The method of thermovacuum electroconductivity (TVE) curves for the analysis of surface phases in disperse systems is described. The theoretical basis of the application of electric measurements for the investigation of the surface of disperse objects is presented. Examples of the use of the TVE-curves method for characterization of diverse catalytic systems and the solving of some problems of heterogeneous catalysis are discussed. The TVE-curves method is an efficient tool for the control of the phase-structural state of the surfaces of objects of a semiconductor type.Translated fromtzvestiya Akademü Nauk. Seriya Khimicheskaya, No. 2, pp. 271–297, February, 1996.     

Qualitative analysis of ultraviolet-absorbing substances by use of fluorescent materials

Developments of detection techniques of ultraviolet absorbing substances with fluorescent materials are reviewed.     

Quantitative thermal analysis V. Role of the flowing gas phase in the analysis of disperse materials

In the analysis of disperse materials, the thermophysical characteristics (rate, thermal conductivity, thermal capacity) of the gas flowing through the pores of the sample are of great importance in determinations of the heats of phase transformations. We have found that the peak areas corresponding to the phase transformations may either decrease or increase with increasing flow rate of the gas. The largest errors (as high as 15%) caused by gas flow in the pores of the disperse material occur when the thermal conductivities of both the solid material and the gas in which the analysis is performed are low. The experimentally derived relationship between the peak area, the flow rate and thermal conductivity of the gas, and the dispersity and thermal conductivity of the solid phase permits calculation of the possible error, and hence application of measures for its reduction.

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Zusammenfassung Bei der Analyse disperser Materialien sind die thermophysikalischen Kenndaten (Geschwindigkeit, Wärmeleitfähigkeit, Wärmekapazität) des durch die Poren der Probe strömenden Gases für die Bestimmung der Phasenübergangswärmen von großer Wichtigkeit. Wir haben festgestellt, daß die den Phasenübergängen zuzuschreibenden Peakflächen mit steigender Strömungsgeschwindigkeit des Gases entweder kleiner oder größer werden. Die größten durch die Gasströmung in den Poren verursachten Fehler (bis zu 15%) treten dann auf, wenn sowohl die Wärmeleitfähigkeit des Festkörpers als auch die des Gases, in dem die Analyse ausgeführt wird, niedrig sind. Die experimentell abgeleitete Beziehung zwischen der Bergfläche, der Strömungsgeschwindigkeit und Wärmeleitfähigkeit des Gases und der Dispersität und Wärmeleitfähigkeit der festen Phase erlaubt die Berechnung des möglichen Fehlers und damit das Ergreifen von Maßnahmen zu dessen Verringerung.

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Methodology and procedure of the stoichiographic analysis of solid inorganic substances and materials

The technical and experimental aspects of creating the conditions of differential dissolution in a flow stoichiographic system are discussed; the scheme of the experimental apparatus, stoichiograph, is presented. The construction, operation conditions of the main units of the stoichiograph, and sample treatment issues are considered. The principles of the creation and optimization of the conditions of the dynamic differential dissolution for the analysis of compounds and materials of the known and unknown phase composition are discussed: the composition of solvents and temperature, and the principles of their variation in time, including those in the processes of stoichiographic titration.     

Synthesis of disperse graphene-like materials and their structural and electrochemical characteristics

Graphene-like materials of oxidized graphite (OG) were obtained by boiling in ethylene glycol, microwave treatment of a suspension of OG in ethylene glycol, and microwave treatment of dry OG without using solvents. The obtained materials were characterized by X-ray photoelectron spectroscopy (XPS), IR spectroscopy, atomic force microscopy, elemental analysis, and electrochemical measurements. Microwave treatment of dry OG gave the most disperse material (～400 m²/g) with an oxygen content of no more than 20%. Treatment in 0.5 M H₂SO₄ for 50 h at 60°C in oxygen did not lead to oxidation and was accompanied by an increase in the dispersity of this material.     

Molecular dynamics study of spectral characteristics of water-carbon oxide disperse systems

Absorption and reflection IR spectra of aqueous disperse systems that absorbed carbon oxide molecules are calculated. Systems of small and large clusters containing 2 ≤ n ≤ 10 and 11 ≤ n ≤ 20 water molecules, respectively, are studied. Each cluster can absorb one or two carbon oxide molecules. Both real and imaginary parts of dielectric permittivity of disperse systems depend on the number of adsorbed CO molecules to a greater extent than that of water molecules in clusters. The integral intensity of the absorption of IR radiation by cluster systems increases after the absorption of carbon oxide molecules by clusters. However, the ability to absorb and reflect IR radiation decreases with an increase in the concentration of absorbed CO molecules. Upon the growth of heteroclusters due to addition of water molecules, integral intensity of the absorption of thermal radiation can be enhanced or damped. In general, the clusterization and capture of CO molecules by clusters result in an anti-greenhouse effect.     

Quantitative thermal analysis. part IV. Role of the stationary gaseous medium in the analysis of disperse materials

In thermal analysis of disperse materials, the gas filling the pores of the samples has an important effect on the determination of heats of phase transformations. Particularly significant errors, up to 25%, may arise in cases when thermal analysis is carried out in gas atmospheres having high thermal conductivities. Based on experimental data, a relationship expressing the dependence of peak area on the thermal conductivity of the gas and on the thermal conductivity and particle size of the studied material has been derived. This relationship allows to calculate the possible experimental error and hence to adopt measures for reducing its value.     

Synthesis and application of doxorubicin-loaded silica gels as solid materials for spectral analysis

A new approach to synthesis and the possibility of application of solid gel matrices containing the target analyte, a cancer drug—doxorubicin for the calibration of UV-vis spectrometers is presented. The doxorubicin-loaded gels were prepared by the acid-catalyzed sol-gel pre-doping method. The efficiency of doxorubicin encapsulation in gels by the sol-gel process was 100 ± 1.2% (w/w). The amount of doxorubicin encapsulated per unit mass of the gel (1 g) was found to be independent of the mass of the gel taken for analysis, which demonstrates the homogeneity of encapsulation of the drug in the gel matrix. The gelation process of doxorubicin in the sol was found to be both repeatable (R.S.D. = 11.2% for n = 80, confidence level P = 95%) and reproducible (largest value of R.S.D. = 4.8% for n = 27, P = 95%).The prepared doxorubicin-loaded gel matrices are characterized primarily by their lack of toxicity as compared to the toxic free form of doxorubicin as well as by high stability over a long-time span.     

The analysis of solid and liquid high-purity substances

This paper reviews the problems of atomic-spectrometry, mass-spectrometry and activation methods in elemental analysis of high-purity substances. The specific techniques of sample preparation, preconcentration of impurities and the determination of gas-forming trace elements are discussed.     

The metrology of unstable measurands

 Type A statistical uncertainty in measurements is usually derived from the standard deviation of the measured data. This is correct as long as the measurand is stable over time and has a meaningful constant value. In such a case the average measurement and the standard deviations are meaningful. However, as measurement methods are refined and become more precise, we can observe that a given measurand may be unstable and change with time and the uncertainty in measurement must be redefined. This is specifically true in the metrology of time which can be measured today more precisly than any other measurand. We argue that in such a case the uncertainty in the prediction of the next measurement should be used instead of the uncertainty in measurement. Both uncertainties coincide for a stable measurand. The prediction of the next measurement is achieved by means of predictors. In this paper we describe the application of linear predictors and especially optimum linear predictors to predict in the presence of various types of instability. To illustrate the issues we use clock instabilities and clock metrology as this field is most developed. A measurand can be unstable but still predictable and thus useful. This is well known in the case of white noise about a linear drift for which the optimum predictor is a linear regression. Since the deviations from prediction of optimum prediction are of white noise, we can now use simple statistics to estimate the uncertainty of the optimum or close to optimum prediction. In this paper we present the various optimum or close to optimum linear predictors optimized for different types of instability and estimate the associated prediction uncertainties.     

Specificity of the application of disperse and fibrous fillers in heterophase polymer materials

The mechanism of the reinforcing effect of fillers in polymer composition is studied and the relation between the properties and structure of materials is established. It is shown that, upon the addition of even a small amount of filler, properties of polymers change markedly due to intermolecular interactions. Variations in the composition of filled polymers and conditions of their preparation make it possibly to regulate properties of polymers within noticeably wide ranges. Specific features of polymer compositions filled with polymer fibers, the effect of fiber length, and the degree of orientation on the strength of composition are considered. For crosslinked epoxy urethane polymers, the effect of glass and polycaproamide (capron) fibers on the mechanical properties of polymer clutches in glassy and rubbery states is studied. The possibility to realize the shape memory effect for shrinkable filled polymer clutches is demonstrated.     

Analyses of hazardous substances in biological materials

Summary The interest of the Commission for the Investigation of Health Hazards of Chemical Compounds in Work Area of the German Science Foundation in practical, sensitive and specific methods for monitoring the limit values led to the establishment of the working group Analytical Chemistry in 1969. A loose-leaf collection Analysen in biologischem Material and 3 volumes of an English edition have since been published. In the meantime the German edition of Analyses in biological materials has been supplemented ten times, including 100 methods for the measurement of about 170 parameters; the English edition is in 3 volumes with 45 selected methods. The volumes include only standard operational procedures that are suitable for routine use. The reliability of the analytical procedures is defined and checked for these reasons and because they satisfy the requirements of statistical quality control. The analytical methods published by the Working Group Analytical Chemistry are recommended by pertinent guidelines and regulations for use in Germany.Dedicated to Professor Dr. Wilhelm Fresenius on the occasion of his 80th birthday     

The use of the ratios of intensities of spectral lines for X-ray fluorescence analysis of metal alloys and oxide materials

An X-ray fluorescence analysis technique is proposed, which is based on using ratios of intensities of spectral lines. The technique includes performing calculations for evaluation of calibration equations, which allows using few reference samples or carrying out standardless analysis, if necessary. That parameters of the calibration equations depend linearly on concentrations of disturbing elements allows one to simplify taking their influence into account. To apply the developed technique to analysis of samples containing a significant amount of undetectable light elements, a use of a dependence of intensity ratio of the characteristic radiation of the X-ray tube’s anode, coherently and incoherently scattered by a sample, on a total content of undetectable elements is proposed. The technique’s adequacy is demonstrated by analysis of standard steel samples, metal cuttings and iron-ore materials.     

An algorithm for selecting marker substances in gas chromatographic analysis of medicinal-plant raw materials

Two complementary chromatographic methods, viz., ion-exclusion chromatography and gas-liquid chromatography, are suggested for studying the chemical composition and the standardization of medicinal-plant raw materials and plant mixtures. An algorithm for selecting one of two methods, which takes into account the component composition in plant mixtures, as well as the classification of marker sub-stances according to the degree of their occurrence in specific types of medicinal-plant raw materials, are proposed.     

Electron spin resonance spectral study of PVC and XLPE insulation materials and their life time analysis

Electron spin resonance (ESR) study is carried out to characterize thermal endurance of insulating materials used in power cable industry. The presented work provides ESR investigation and evaluation of widely used cable insulation materials, namely polyvinyl chloride (PVC) and cross-linked polyethylene (XLPE). The results confirm the fact that PVC is rapidly degrades than XLPE. The study also indicates that colorants and cable's manufacturing processes enhance the thermal resistance of the PVC. It also verifies the powerfulness and the importance of the ESR-testing of insulation materials compared to other tests assumed by International Electrotechnical Commission (IEC) Standard 216-procedure, e.g. weight loss (WL), electric strength (ES) or tensile strength (TS). The estimated thermal endurance parameters by ESR-method show that the other standard methods overestimate these parameters and produce less accurate thermal life time curves of cable insulation materials.     

Methods of obtaining ultrathin sections of highly disperse materials for electron microscopy

Conclusions Comparative data on the suitability of methacrylates, epoxide resins ÉD-5 and ÉD-6 and compound K-156 for casting polycrystalline materials into blocks for electron-microscopic investigation have been obtained. K-156 gave the best results.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1350–1351, June, 1967.     

The meaning of measurement in metrology

The latest version of the International Vocabulary of Metrology gives a meaning of measurement restricted to quantities that can be represented by numerical values and placed in an ordinal sequence. This restrictive definition fits poorly with both the colloquial and the wider scientific understanding of measurement. This paper suggests an extension to the metrological definition of measurement, based on the measurement classification scheme of Stevens, to incorporate non-numerical and nominal measurements. The more inclusive definition and the classification scheme offers insights into the utility, metrological traceability, and limitations of measurements and uncertainty treatments, and enables clarification of other measurement-related definitions.