Wollastonite ceramic was obtained from chalk and diatomite by solid-phase synthesis of the components. The influence of the batch composition, regimes of mechanochemical activation, and ...thermophysical properties of the ceramic materials were investigated. As a result of the combined mechanochemical activation of the batch components (chalk + diatomite), the temperature of the solid-phase synthesis of wollastonite ceramic was lowered to 900°C. After 2-h firing, the mineral wollastonite comprised almost 90% of the ceramic samples. The compressive strength of the samples is 22 – 23 MPa at an apparent density of 1270 – 1300 kg/m
3
. The material has a stable linear thermal expansion coefficient (CLTE) not exceeding 7.76 × 10
–6
K
–1
. It can operate at temperatures up to 1100°C inclusively. Samples of heat-insulating material with an average density of 435 kg/m
3
, compressive strength 2.2 MPa, coefficient of thermal conductivity 0.099 W/(m ∙ K) and limiting operating temperature up to 1050°C inclusive were obtained from the developed batch and expanded perlite. The developed materials can be used as refractory heat insulation for industrial furnaces, equipment, and elsewhere.
The ultrasound-assisted extraction method for isolation of 17 sugars and sugar alcohols from conifers with a subsequent hydrophilic interaction liquid chromatography-tandem mass spectrometry method ...for their determination is proposed. The optimization of extraction parameters was carried out using Taguchi – L9 (34) orthogonal array experimental design for the following parameters—a methanol concentration in the extraction solution, an extraction time, a type of plant sample and an extraction temperature. The optimal ultrasound-assisted extraction conditions were—MeOH concentration – 30% (water – 70%), extraction time – 30 min, type of plant sample – II (grinded leaves 2–4 mm long), extraction temperature – 60 °C. Pure water and acetonitrile were used as eluents in gradient elution mode to separate the analytes. Direct determination of multiple sugars and sugar alcohols was carried out using a mass spectrometric detector operated in a multiple reaction monitoring mode, providing detection limits in the range between 0.1 and 20 ng/mL and good analytical characteristics of the method without derivatization. The developed approach was validated by multiple successive extraction method applied to test its performance on a series of 10 samples, i.e. 2 samples per each of 5 genera: Abies, Larix, Picea, Pinus (Pinaceae) and Juniperus (Cupressaceae), widely distributed in the boreal conifer forests of Eurasia. The novel strategy can be used for profiling of sugars and sugar alcohols in a wide range of plant species.
•Optimization & validation of HPLC-MS/MS method for sugars and polyols determination.•Sugars and polyols isolation from conifers by ultrasound assisted extraction.•Optimization of ultrasound assisted extraction parameters by orthogonal array design.•Method applicability was verified in the analysis of 5 conifers.
This paper considers publications devoted to the development and improvement of methods for the determination of markers and biomarkers of chemical warfare agents (CWAs) using various combinations ...and modifications of gas and liquid chromatography–mass spectrometry. Attention is focused on the importance of choosing an optimal analysis strategy and optimizing sample preparation procedures and operating modes of analytical instruments. Published data on the selection of characteristic markers of organophosphorus CWAs and sulfur mustard gas and methods for their determination are summarized.
Despite the fact that the global market for medicinal plants amounts to hundreds of billions of dollars, there is almost no government control over the quality of such pharmaceuticals in most ...countries of the world. This is partly attributed to the complex composition of plant materials: traditional analytical methodology is based on the use of standard reference samples for each analyte. In this case, preparations based on medicinal plants may contain tens and hundreds of physiologically active components. Isolation of those compounds in a pure form in practice is carried out using preparative chromatography, which leads to their high cost. Moreover, variation of the chemical composition of medicinal plants depending on the geographical origin of the raw materials interferes with prescribing strict ranges of permissible contents for all physiologically active components. The combination of the above factors limits the possibilities of using traditional approaches to analysis requiring strict standardization, the list of compounds for each type of plant, levels of contents, and the availability of reference materials and standards of comparison. This led to the study of the possibility of introducing various mathematical approaches as an auxiliary methodology. Unlike traditional methodologies, machine learning approaches are based on the correct collection of the data samples. Such a sample should contain groups of samples that correspond to the states of the object which the developed algorithm must distinguish: authentic/fake, pure/containing impurities, effective/not containing a certain level of active components, etc. This review is devoted to consideration of the application of machine learning techniques to the problems of chemical analysis and production control of raw materials of medicinal plants and preparations on their basis for the last 15 years.
We developed a method for determining ethyl methylphosphonic, isopropyl methylphosphonic, isobutyl methylphosphonic, and pinacolyl methylphosphonic acids in human urine using gas chromatography with ...high-resolution mass spectrometry and preliminary derivatization with
p
-methoxyphenacyl bromide. All of the acids are specific hydrolysis products and biomarkers of nerve agents. Conditions of the derivatization reaction were optimized. Features and general patterns of the MS
1
and MS
2
spectra of derivatives acquired in electron and chemical ionization modes are revealed. The developed method achieved the limits of detection in the range from 20 to 70 ng/mL.
Substitution reactions in carbocyanine dyes are used to determine nucleophilic compounds. The interaction of a chlorine-containing carbocyanine dye with a number of medicinal substances is studied. ...It is shown that, in the reaction with isoniazid in the presence of a surfactant, this dye selectively changes color from yellow-green to violet. The formation of a product of the substitution of chlorine for isoniazid is proven by chromatography–mass spectrometry. The reaction proceeds in 20 min in the presence of 1 mM cetyltrimethylammonium bromide. The limit of detection for isoniazid in water by the photometric method is 10 μg/mL and in diluted artificial urine using fluorimetry, 0.3 μg/mL. The procedure does not use full-spectrum equipment, which simplifies the determination.
Monometallic palladium and bimetallic palladium-iron catalysts (1 wt% Pd, 10 wt% Fe) were prepared by sequential (denoted as “-s”) and co- (denoted as “-c“) impregnation of alumina and silica – ...zirconia (ZS) supports with metal nitrates. After reduction with H2 at 320 and 30 °C the catalysts were tested in hydrodechlorination of diclofenac in water at 30 °C in batch and flow-type reactors. The alumina-supported catalysts were more active than the ZS-supported ones, while the bimetallic catalysts were more efficient than the monometallic Pd ones. The co-impregnated bimetallic catalysts showed higher efficiencies than the catalysts prepared by the sequential deposition of metals. Pd/Al2O3 and PdFe/Al2O3-c provided the same rate of DCF conversion in the batch reactor after both types of preliminary reduction, opening the way for energy saving. The catalysts were studied by XRD, TEM, SEM-EDX, low-temperature N2 physisorption, Mössbauer spectroscopy, DRIFT-CO and by XPS after in situ reduction at 320 °C and ex-situ reduction at 30 °C. The improvements in catalyst efficiency resulted from wider pores, formation of PdFe alloys or Pd-Fe-Ox species on the surface, high Pd0/Pd2+ ratio, low extent of Pd encapsulation with the support and especially its coordinately unsaturated sites. The encapsulation degree was the lowest in the co-impregnated catalysts.
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•Catalytic hydrodechlorination of diclofenac in aqueous solutions at 30 °C.•Pd and PdFe catalysts on alumina are more efficient than on silica-zirconia (ZS).•Catalytic efficiency depends on the sequence of support impregnation by metals.•Reduction of Pd by H2 at 30 °C can be nearly as efficient as at 320 °C.•Electronic states of Pd and Fe on the surface was determined by XPS.
A method has been optimized for simultaneous extraction of ethyl methylphosphonic acid ester (EMPA), isopropyl methylphosphonic acid ester (IPMPA), isobutyl methylphosphonic acid ester (IBMPA), ...pinacolyl methylphosphonic acid ester (PMPA), and methylphosphonic acid (MPA), which are highly polar products of nerve agent hydrolysis, from soil with their further determination by high-performance liquid chromatography–high-resolution tandem mass spectrometry (HPLC–HRMS/MS). The ions observed in the fragmentation mass spectra of deprotonated EMPA, IPMPA, IBMPA, PMPA, and MPA molecules and their deuterated analogs (d3-EMPA, d3-IPMPA, d3-IBMPA, d3-PMPA, and d3-MPA), as well as possible structural formulas of the fragment ions, are presented. Liquid extraction with deionized water followed by concentration by evaporation was used to prepare soil samples for analysis. The components were separated using reverse-phase chromatography. The time required for the sample preparation and analysis of the soil samples was no more than 1 h. The detection limits in soil were 0.05 ng/g for EMPA and IPMPA, 0.02 ng/g for IBMPA and PMPA, and 1 ng/g for MPA.
Reducing industrial slags and developing building materials on its basis is one of the priority areas for the development of the construction industry. The problem of obtaining cellular concrete from ...mineral wool production waste (lightweight geopolymers) is considered within the framework of the researches, the results of which are presented in the article. The research purpose was to establish the impact of composition of the raw material mixture and technological production features on the physical, mechanical and thermophysical properties of light geopolymers based on mineral wool production waste. Light geopolymers were obtained by preparing a mixture of ground slugs (specific surface is 400±20 m2/kg), alkaline activator (NaOH), water, a gas-forming additive (aluminum powder), fine aggregate and a water-holding additive. The resulting mixture was placed in the form without vibration. Molded products were steamed in order to accelerate hardening. The mobility of mortar mixtures was studied during the work, the average density, compressive strength, and thermal conductivity was studied for hardened samples. The compositions of lightweight geopolymers with an average density from 610 to 1,130 kg/m3, compressive strength from 1.7 to 5.4 MPa, and a thermal conductivity from 0.144 to 0.345 W/m∙°C were obtained. The application of the results will contribute to the expansion of the raw material base for obtaining light geopolymers, thereby reducing the amount of waste generated during the mineral wool production. The developed materials can be used for the construction of walling, and also as the insulation of the roof and floor of industrial and civil facilities.
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