The development of new methods for the analysis of chemical markers in biological fluids is an urgent area of research, because it is focused on solving socially significant tasks related to healthcare, chemical safety of the population, and countering terrorism. In this regard, new methods for the analysis of metabolites and exogenous substances in the body using alternative biological fluids available for non-invasive sampling are being actively studied and developed. In this paper, the authors present the results of developing and testing an approach for express determination of micro concentrations of volatile organic substances in the lipid layer of human skin by gas chromatography/mass-spectrometry (GC/MS) using a simple procedure of non-invasive sampling without a sample preparation stage. Samples of the lipid layer were collected using adhesion arising from mechanical contact of a metal carrier made of a piece of wire with the skin’s surface, and were analyzed without any additional sample preparation. A field chromatograph-mass-spectrometer with a custom made attachment for introducing samples with flash thermal desorption, previously designed by the authors, was employed for performing analyses. The qualitative composition of trace impurities in the lipid layer of the skin was characterized in the samples collected from 25 donors during the approbation of the method; identified impurities included technological additives to common plastics, psychoactive substances, medicines. It was shown that the impact of sample size variability during sampling on the repeatability of analytical results can be significantly reduced by using one of the main matrix components (e.g., squalene, oleic or palmitic acid) as an internal standard. The analysis time, including sample preparation, did not exceed 15 minutes. The feasibility of using the proposed approach for therapeutic drug monitoring with a 5-minute analysis frequency was demonstrated using caffeine as an example. An increase in caffeine content in the skin lipid layer (relative to oleic acid) in the range of 0.02 % to 2 % was experimentally observed after consumption of caffeine; the pattern of concentration changes differs significantly for different modes of consumption.
The contribution of Rostov-on-Don X-ray physicists (Professor M.A. Blokhin's school) to the development of theoretical foundations and practical techniques for applying X-ray spectral analysis (XRSA) is considered. The review provides a detailed examination of the peculiarities of XRSA specialist training at Rostov-on-Don State University (Southern Federal University from 2006) and the organization of XRSA research work in Rostov-on-Don. In the initial period (1960–1970) the main attention was paid to testing the capabilities and improving the analytical methods that were novel for that period. These were the Beattie-Brissi method, the calibration method, the standard-background method, and the additives method. Subsequently, research based on the application of theoretical assessment of matrix effects in XRSA (assessment of the contribution of selective excitation to the intensity of analytical lines, assessment of the influence of sample heterogeneity and options for accounting for this influence on the intensity of analytical lines for some practical cases, application of the theoretical correction method) became a priority. Other directions, such as the use of proton- and ion-excited X-ray spectra; the development of equipment for XRSA variants with total external reflection of primary radiation; and the practical application of energy-dispersive spectrometers with secondary emitters, were developed. The contribution of the Rostov University’s Basic Research Laboratory of X-ray Spectral Analysis staff to the development and implementation of automated analytical control systems at non-ferrous metallurgy enterprises is noted. The contribution of the research groups led by M.A. Blokhin, N.F. Losev, and their students, V.F. Volkov, V.I. Chirkov, Sh.I. Duimakaev, V.V. Druz, Yu.I. Velichko, V.P. Krasnolutsky, A.L. Tsvetyansky, and M.I. Mazuritsky is briefly discussed. Rostov-on-Don X-ray physicists, graduates of Rostov State University (and Southern Federal University) have worked in scientific and industrial laboratories throughout the Soviet Union, and currently continue to work in Russia and other countries.
Organic carbonates of linear and cyclic structure are widely used as "green" solvents, reagents or additives in organic synthesis and polymer chemistry. Organic carbonates have found their main application as electrolytes for lithium-ion batteries. The organic carbonates do not have toxic properties, however when released into the atmosphere they undergo photooxidation forming substances harmful to the environment (carbon mono- and dioxide, formaldehyde, etc.). Methods of determination in working area air have been developed for some organic carbonates. Large-scale production and use of organic carbonates leads to pollution of air, waste and natural waters, and soils. The aim of this work is to study the methods of extracting linear and cyclic carbonates from solid media (sand, soil) with subsequent gas chromatographic determination. Head-phase extraction was used to extract linear carbonates; extraction with an organic solvent with subsequent concentration was employed in case of cyclic carbonates. The conditions for performing extraction were determined. The limits of determination were (1–2) µg/g for linear and (8‒10) µg/g for cyclic carbonates. The methods of determination are simple, rapid, and the measurement error does not exceed 10 %. Studies of the residual content of organic carbonates in soil after exposure to open air at 25 °C and 35 °C were conducted. It was established that linear carbonates are released from the soil at the highest rate. Cyclic carbonates do not pass into the gas phase; they remain in the solid matrix and undergo chemical transformation. Increasing temperature from 25 °C to 35 °C does not affect the process of decreasing the content of cyclic carbonates in soil but only affects the removal of linear carbonates.
The effect of composition of canned fruits and vegetables on chromatographic separation of azo-, triphenylmethane, and indigo carmine dyes currently approved for use in the Russian food industry was studied. The study was carried out on a Shimadzu liquid chromatography instrument as a part of efforts to develop a regulatory and technical framework for the control of artificial dyes in food products. The conducted studies revealed the presence of undeclared synthetic dyes in ketchup, which, also according to the Technical Regulations of the Customs Union “Food products in terms of their labeling” (TR 022/2011, effective from July 1, 2013), the manufacturer is obliged not only to indicate, but also to give the following warning to buyers: “It contains a dye that can have a negative effect on children's activity and attention”. The study also showed the need to develop and disseminate new state standards for more types of food products.
Aliphatic (fatty) acids and closely related lipids of various structures constitute the most extensive group of organic compounds in plants, which can act as markers of the physiological state and the degree of reaction of environmental factors on plants. To determine aliphatic carboxylic acids (C12-C24) in plant materials we proposed an approach that combines the stages of the acids’ extraction and derivatization in methanol (one-step extraction/methylation method) followed by determination of the resulting esters by gas chromatography with a flame ionization (GC-FID) or a mass spectrometry (GC-MS) detector. Optimization of acid extraction from plant samples and their methylation was carried out using the following parameters: the mass ratio of the extractant and the sample during extraction, the concentration of hydrogen cations (catalyst), the duration of extraction, and the temperature of the reaction mixture. It was shown that the degree of extraction of fatty acids and lipids from a plant sample under the selected optimal conditions reaches 97–99 %. A method for determination of fatty acids (C12–C24) in plant materials was developed. The range of determinable contents is 0.005–0.5 mg/g, the relative error is 15–20 %, the sample weight is 0.2–0.25 g, the total analysis duration is 2.5 hours. The qualitative and quantitative composition of fatty acids in medicinal plants – hyssop (lat. Hyssopus officinalis) and motherwort (lat. Leonurus cardiaca) – was assessed. Ten carboxylic acids were identified in the medicinal plants studied, i.e. seven saturated (dodecanoic, tetradecanoic, hexadecanoic, octadecanoic, eicosanoic, docosanoic, and tetracosanoic) and three unsaturated (octadecenoic, octadecadienoic, and octadecatrienoic). Hexadecanoic and linolenic acids are found in the highest quantities in plants of the Lamiaceae family.
Molecularly imprinted polymers (MIPs), known for their high specificity and durability, have emerged as promising materials for the development of eco-friendly sensor platforms capable of detecting pharmaceutical compounds in complex matrices. In this work, amperometric sensors based on MIP were obtained for determination of streptomycin sulfate (Strep) and neomycin sulfate (Neo) antibiotics. Both sensors, MIP-Strep and MIP-Neo, demonstrated a linear dependence of the current difference on concentration in the range of 1.0.10–1–1.0.10–5 g/dm3. The detection limits of the analytes by the sensors were 5.8.10–6 g/dm3 (MIP-Strep) and 7.2.10–6 g/dm3 (MIP-Neo), which are below the maximum permissible concentrations. MIP-Strep and MIP-Neo sensors demonstrated high selectivity for their target molecules. The ability of the sensors to selectively recognize target molecules was estimated using the imprinting factor. For MIP-Strep the imprinting factor (IF) was 4.3, and for MIP-Neo – 6.3. Low sensitivity of the sensors to other antibiotics (sodium ceftriaxones, sodium cefazolins) was established. The sensors demonstrated high selectivity: MIP-Strep – to streptomycin, and MIP-Neo – to neomycin, even in binary solutions. The “introduced – found” method established high accuracy of MIP-Strep and MIP-Neo amperometric sensors in determining antibiotics with a relative standard deviation (Sr) ≤ 5%. HPLC was used as a reference method to check the correctness of Strep and Neo determination by amperometric sensors with MIP. It was found that there were no statistically significant differences between the results of the two methods for determining antibiotics. This opens up prospects for using MIP-based sensors for food quality control, especially for detecting target antibiotics in milk and dairy products. Thus, when analyzing milk samples using HPLC and MIP sensors, Strep and Neo were not detected.
A method for determination of rodenticides in pathological material by high-performance liquid chromatography-tandem mass spectrometry is proposed. Various sample preparation methods were compared in the course of developing the methodology. As a result of the comparison, a method that includes liquid extraction using methanol and further purification of the extract by solid-phase extraction on C18 sorbent was selected. The developed technique was validated, the detection limits were 2–5 μg/kg. The relative standard deviation of the analysis results does not exceed 20 %. The matrix effects in the determination did not exceed 25 %.
An improved process for separating water-oil mixtures in laboratory conditions using a specially developed device is presented in the article. To assess the efficiency of the device, samples of two types of water-oil emulsions were studied: three samples of the inverse type (water in oil) based on high-viscosity oils and six samples of the multiple type (water in oil in water) based on light oils. Comparison with standard laboratory separation methods based on physical, chemical and physicochemical effects was made. Analysis of the results revealed a number of disadvantages of the standard methods, which consist in a significant duration of the process, the need to use several laboratory tools, leading to increasing the time costs for preparing a dehydrated hydrocarbon phase. To separate particularly stable emulsions, especially based on high-viscosity oils, it was necessary to consequently use several methods. A developed laboratory device is proposed as an alternative. It consists of two main modules: 1) a 3.5 dm³ metal vessel made of stainless steel and equipped with a ceramic heating ring, an adapter, and a reflux condenser with a tank for collecting low-boiling fractions; 2) a 400 cm³ vessel with a drying agent (calcium chloride) having a drain hole. The modules are connected via a peristaltic pump, which provides the transfer of the hydrocarbon phase between them at a controlled rate. Separated hydrocarbon phase undergoes additional purification from residual water in the vessel with the drying agent and is collected in the receiving tank. The optimal operating parameters were established: heating temperature of 50–60 °C for light oils and 90–100 °C for high-viscosity oils; peristaltic pump pumping rate of 3 l/h. The efficiency of the device was assessed by passing each sample through the device nine times. In all cases the dehydration degree of 99% was achieved. The use of the device accelerates and simplifies preparation of samples, which are represented by emulsions of various types.
A technique for determining physical parameters of nanoparticles in water by the induced lattice method with their preliminary granulometric separation is proposed. Methods for water sample preparation are recommended. Microflora nanoparticles were identified after heat treatment of a water sample in a microwave sample preparation system. Diamagnetic nanoparticles in water were separated in a magnetic field. Results of determination of Fe and Ni by mass spectrometry showed that good separation of ferromagnetic particles in the magnetic field. Solid polymer materials were extracted from water by hexane. Selective extraction of polystyrene particles from aqueous solutions was established. Physical parameters of the particles were measured using an IG-1000 Plus particle size analyzer (Shimadzu, Japan). The measurement parameters were optimized. The developed technique was used for determining shape, composition, number, surface area, diffusion coefficient and zeta potential of particles, mass concentration of elements in natural and drinking water. The methodology was included in the unified register of certified methods in the territory of the Russian Federation (FR.1.31.2025.52154). Analysis of the granulometric composition of suspended particles in water can be used to validate water purification methods at water treatment plants and assess the effect of particles on possible toxic effects after they enter the body.
A method for determination of tricyclic antidepressant amitriptyline in human urine by amperometric immunosensors based on screen-printed graphite electrodes modified with electrochemically deposited nickel hydroxide nanoparticles and carbon nanomaterials in combination with derivatives of calix[4]arenes is proposed. Various combinations of carbon materials (carbon nanotubes, buckypaper), calix[4]arenes and their derivatives (thiacalix[4]arenes, aminothiacalix[4]arenes) and electrochemically deposited nickel hydroxide nanoparticles are considered. The current of the oxidation peak of nickel hydroxide nanoparticles is selected as an analytical signal, potential of which is shifted by 220 mV due to addition of a bio-detecting component (antibodies) to the composite modifier. Different types of immunosensors varying in the composition of carbon materials are considered. Varying the composition of the composite modifier affects the change in the peak oxidation current of nickel hydroxide nanoparticles in the presence of amitriptyline, which affects the analytical capabilities of immunosensors. The best analytical characteristics, i.e. the concentrations range of 1×10–9–1×10–5 M and the lowest limit of detection of 5×10–10 M (at Sr = 0.33), were obtained for an amperometric immunosensor modified with buckypaper (KMnO4 mass equivalent of 0.9, not annealed in the furnace) with aminothiacalix[4]arene and electrochemically deposited nickel hydroxide nanoparticles. A method for determination of amitriptyline in human urine by amperometric immunosensors based on composite materials has been developed. The relative standard deviation in the determination of amitriptyline does not exceed 0.075.
The situation resulting from penetration of erroneous terms and definitions into metrological (analytical) practice and identification of such different concepts as the standard sample and the reference material, which inevitably will lead to unreliability of the results of quantitative chemical analysis, is considered.
The effect of structure of alkyl substituents in the molecule of sorption materials based on 10-alkylphenoxarsines was studied by gas-liquid chromatography. Chromatographic factors of Rorschneider polarity and the absolute retained volumes of standard sorbates were determined. It is shown that the studied series of 10-alkylphenoxarsines is characterized by low values of chromatographic polarity factors and, according to the Rorschneider classification, belong to weakly polar sorption materials in which the order of elution of components from the chromatographic column is determined by an increase in their boiling points. The dependences linking the chromatographic factors of the Rorschneider polarity in a five-dimensional space are found. It is shown that increasing chain length of the alkyl substituents in the 10-alkylphenoxarsin molecule results on decreasing the overall chromatographic polarity of the sorption materials under study. The absolute retained volumes of standard sorbates showing a certain effect of alkyl substituents in the 10-alkylphenoxarsin molecule were determined. The lowest retention characteristics are observed for ethanol, which is capable of forming intermolecular hydrogen bonds with the sorbate molecule. A linear relationship linking the absolute specific retention volumes of standard sorbates with the number of carbon atoms in the 10-alkylphenoxarsin molecule was established, separately for even and odd substituents for methyl ethyl ketone, nitromethane, ethanol and benzene, with a deviation from it for the first members of the homologous series (CH3, C2H5) to higher retention values. In all cases, 10-alkylphenoxarsines with even substituents are characterized by higher values of the absolute specific retention volume of standard sorbates. This indicates that the intensity of the intermolecular interaction in the sorbate-sorbent system is more significant for even alkyl substituents than for odd ones.
Multitargeted metabolomic analysis is an effective tool for clinical diagnostics, which allows simultaneous profiling of a wide range of metabolites. The aim of the present study was developing and validating a method for targeted metabolomic profiling of blood plasma samples using HPLC-MS/MS and MS/MS methods. Sample preparation, derivatization conditions, and chromatographic–mass spectrometric detection parameters were optimized. Validation of the method was performed in accordance with the Guidelines for Interstate Standardization RMG 61-2010 and the ICH M10 Guideline on Bioanalytical Method Validation for Endogenous Compounds. A software application, Metaboscan AI, was developed to enhance the reliability of processing results of multitargeted data analysis. This tool automates data handling, including peak integration, concentration calculation, and quality control. For cohort studies, the application also supports comparative statistical analysis. The use of tools like multiple linear regression allows the assessment of the effect of biological cofactors (sex and age), thereby improving the interpretability of the results.
The work is devoted to the peculiarities of chlorine and lead determination in dust emissions of gas cleaning vents of electric steelmaking by energy-dispersive X-ray fluorescence analysis (EDXRF). A technique has been developed for the express energy-dispersive X-ray fluorescence determination of chlorine and lead in dust emissions of gas cleaning vents using powder model mixtures as standard samples similar in composition to real samples of dust emissions of gas cleaning vents. The analytes were determined using the characteristic ClKα1,2 and PbLα1,2 radiation lines. The possibility of reducing interfering effects of braking and characteristic radiation from the X-ray tube with an aluminum filter in the determination of chlorine, achieved by increasing the signal to background ratio for characteristic ClKα1,2 radiation line, is considered. The uncertainty of EDXRF method for determining chlorine and lead in dust emissions of gas cleaning vents was estimated using additional model mixtures. The calculation of accuracy indicators, repeatability limits, and intra-laboratory precision was carried out for energy-dispersive X-ray fluorescence determination of chlorine and lead in dust emissions of gas cleaning vents according to the obtained equations. It was shown that the results for chlorine determination in samples were overestimated (up to 7.7 %) relative to the accepted reference value if no filter was used, and were underestimated (up to 4.4 %) when the filter was present. For lead, the maximum deviation from the accepted reference value was 10.6 %. Constructed calibration graphs and pelleted model samples are stable for several months. Satisfactory consistency of the results of energy-dispersive X-ray fluorescence determination of chlorine and lead with data from standardized methods for analyzing real samples of dust emissions of gas cleaning vents was obtained; standard deviations did not exceed 13 % for lead and 11 % for chlorine. The proposed EDXRF method for the determination of lead and chlorine in dust emissions of gas cleaning vents is more efficient and less laborious.
The possibilities and features of using the double internal standard method are considered on the example of quantitative determination of 1-heptanol in a solution. Two homologues of the target analyte, 1-hexanol and 1-octanol, were selected as the standards. The advantage of this method, in difference from the “common” version of the internal standard technique, is the absence of the necessity of preliminary determination of the calibration coefficients, since the possible differences in the sensitivity of detection of different homologues are mutually compensated. Analysis of the results allowed revealing the main reasons of systematic errors and eliminating two principal of them. The first source of errors is the features of dozing microamounts of standards to samples, which can be accompanied by poorly quantifiable losses. The second source of the error is storage of hydrophilic aliphatic alcohols in contact with air, which can be accompanied by absorption of water vapors resulting in decreasing real content of standards in the samples and overestimation of analysis results. Third factor resulting in a slight underestimation of the results is a slight increase of the volume of samples after standards addition. Besides that, as it was proposed by the author of this method (Mark S. Vigdergauz, 1986), final result of analysis is presented as the geometric mean of results calculated for each standard. However, besides geometric means, calculation of average harmonic values is possible, thus slightly reducing overestimation of the results but complicating the calculations.
The effect of concentration of mercaptopropyl groups chemically fixed on the surface of silica on formation of surface mixed-ligand copper(I) complexes with grafted mercaptopropyl groups and dithizone is considered. Treatment of silicas chemically modified with mercaptopropyl groups (MPS) with the concentration of 0.22 mmol/g, 0.50 mmol/g and 0.70 mmol/g, containing copper(I) with 1 10–5–1 10–4 M dithizone solutions results in the development of brown coloration on the surface of the sorbents, characteristic of copper(I) dithizonates in aqueous solutions. Diffuse reflectance spectra of the mixed-ligand copper(I) complex with mercaptopropyl groups and dithizone on the sorbent’s surface are represented by broad absorption bands with a maximum at 440 nm. The intensity of the sorbent color increases with decreasing surface concentration of mercaptopropyl groups and with increasing copper content on their surface. Formation of colored mixed-ligand copper(I) complexes on the silica gel surface was used in developing methods for sorption-photometric determination of copper using diffuse reflectance spectroscopy. The developed method for sorption-photometric determination of copper was used for analysis of rinsing waters of the copper tube etching section.
The hydrocarbon composition of the diesel fraction (boiling point range of 180–315 °C) of tire pyrolysate was determined before and after its hydrogenation on aluminoplatinum and aluminum-nickel-molybdenum catalysts using preliminary extraction sample preparation and subsequent GC-MS analysis, as well as standard physicochemical methods for analyzing petroleum products. Pyrolysis was carried out at 500 °C in nitrogen atmosphere. Hydrogenation was performed in an autoclave using hydrogen under pressure of 6.5–6.8 bar and temperature of 350–360 °C. The sample preparation technique included extraction of samples before and after hydrotreating using n-hexane, as well as extraction of water-soluble components using alkaline and acidic solutions. Using the extraction-chromatographic method it was found that the original diesel fraction contained small amounts of water-soluble components. Treatment of the fraction with oleum allowed to selectively determine the content of saturated hydrocarbons in the pyrolysate since alkenes and arenes are destroyed by oleum. Based on the results obtained it was concluded that the studied fraction of the pyrolysate could not be used as a component of motor fuels due to the high content of sulfur and alkenes. Hydrogenation on a platinum catalyst noticeably reduces sulfur and alkenes content but it remains quite high. The use of an alumina-nickel-molybdenum catalyst in hydrotreating allows for a sharp reduction in the content of the above components but at the same time the content of aromatic hydrocarbons increases significantly. The pyrolysate obtained during hydrogenation on this catalyst can be considered as a potential additive to commercial petroleum products since it contains virtually no sulfur or olefins.
An illustrated bibliographic index of printed and electronic publications (monographs, textbooks, collections of articles, materials of symposia and conferences, standards, teaching aids) on the creation, development and application of a powerful modern analytical method of inductively coupled plasma mass spectrometry (ICP-MS) has been compiled. The time range of the index covers the period from the publication of the first editions devoted to ICP-MS to the present. The index presents printed and electronic publications significant for the scientific and practical work of analysts, published in various countries. For each publication, a full bibliographic description and a brief annotation are provided. Most publications in the index are accompanied by illustrations of covers or title pages, as well as electronic addresses or identifiers. This allows you to quickly and easily find a publication on the Internet. The index is intended for the scientific and practical activities of analysts specializing in the field of atomic spectral analysis.
A planar electrochemical sensor based on a screen-printed carbon electrode (SPE) modified with a zeolite-like imidazolate metal-organic framework ZIF8 and graphene was developed for determination of the synthetic analgesic tramadol using linear sweep voltammetry. Modification of the electrode with a nanocomposite modifier increased its surface by 1.6 times and aided in a three-fold increase in the peak current of tramadol oxidation. It was shown that the highest tramadol oxidation current was recorded at 10 % ZIF8 in the nanocomposite modifier and using a phosphate buffer solution with pH 7 as a background electrolyte. A shift in the potential of the tramadol oxidation peak by 130 mV to the lower values was observed on the modified electrode compared to the unmodified one. It was found that tramadol electrooxidation on graphene-ZIF8/SPE is an irreversible adsorption-controlled process involving one electron. The parameters of tramadol electrooxidation were calculated and a scheme of the electrode reaction proposed. The detection limit of tramadol and the linear range of the sensor are 0.01 μM and 0.25–1800 μM, respectively. The sensor exhibits high selectivity for a number of compounds accompanying tramadol in real samples, which allows its use in the analysis of artificial blood serum and pharmaceuticals in the form of tablets and injection solution. The correctness factor of 96–105 % proves the absence of a systematic error in tramadol determination; and the relative standard deviation not exceeding 5 % indicates good repeatability of the analytical results. The absence of additional separation and concentration stages makes the analysis using graphene-ZIF8/SPE highly expressive.
CuKβ X-ray emission spectra were studied for mineral samples containing copper in various forms. The measurements were performed on an X-ray fluorescence wavelength-dispersive spectrometer designed for elemental composition analysis and having a relatively low energy resolution of about 30 eV at a CuKβ line emission energy of 8.905 keV. The spectra were obtained using a lithium fluoride LiF (220) crystal analyzer. The features of the spectra of various mineral forms of copper are manifested as asymmetry of the shape and shift of the maximum of the CuKβ line: the spectra of mineral samples containing predominantly monovalent copper in the form of oxides (cuprite) and sulfides (chalcocite, bornite) differ significantly from the spectra of minerals containing predominantly divalent copper in the form of sulfides (chalcopyrite) and copper hydroxide sulfates (antlerite, brochantite), but are close to the spectra of minerals containing divalent copper in the form of a copper carbonate hydroxide (malachite, azurite). Spectra of sulfides and hydroxide sulfates of divalent copper are not distinguishable within the measurement error. Measuring the shape of the CuKβ X-ray emission spectrum allows obtaining additional information on the mineral forms of copper in copper ores.
