Vol 80, No 3 (2025)

One of the pronounced trends in modern analytical chemistry is increasing availability of chemical analysis for mass consumers. By now, a large number of produced test kits for semi-quantitative analysis and a number of devices for evaluation of compliance of individual parameters of the analyzed object with the required standards have appeared. The review systematizes and discusses the main existing solutions in this field today, proposed for food analysis, and reflects the current state of the art in this area. According to the authors opinion, the concept of accessibility of this or that accessory is largely determined by its availability on the market and its acceptable cost for an individual buyer, so the review focuses on commercialized analytical tools costing mainly up to 100 thousand rubles. Relatively inexpensive and easy-to-use test tools, portable electrochemical, spectroscopic, refractometric, ultrasonic systems, as well as electronic nose type systems for chemical analysis are considered, their main characteristics and approximate cost are given. Suggestions are made about the prospects of further development of chemical analysis instruments available for mass consumers.

Determination of microplastic content in natural waters is an urgent task in assessing the degree of pollution of water bodies, identifying sources of pollution, as well as in assessing potential risks for inhabitants of aquatic ecosystems and water consumers. The solution of such a problem mainly lies in the field of analytical chemistry, with particle separation methods playing the most important role. The present work shows for the first time the possibility of applying the method of flowing microplastic separation in a rotating spiral column using a water-oil system to assess the content of microplastics in river water. Microplastics in the extracted particle samples were determined by pyrolysis gas chromatography with mass spectrometric detection (Pyro-GC-MS). A water sample from the Moskva River was analyzed. Using the water-castor oil system, 1.8 mg/L of suspended solids were separated from river water. The decomposition procedure of the organic matter (30 % H₂O₂) of the sample reduced the mass of extracted particles to 0.4 mg/L. The residual fraction was studied by optical microscopy. According to the Pyro-GC-MS data, the total content of microplastics in the studied water sample was 109 µg/L, which is 1.4 % of the total suspended solids in the studied water sample. Five types of microplastics, namely polyethylene, polypropylene, acrylonitrile butadiene styrene, acrylonitrile butadiene rubber and polyethylene terephthalate, among which polyethylene is the main type (97 µg/l), were identified. The proposed method is promising for estimation of microplastic content in natural waters.

The work is devoted to the evaluation of the efficiency of the extraction of volatile organic compounds from flowers of wild chamomile (Matricaria chamomilla L.). The chromatographic-mass spectrometric determination of volatile organic compounds (VOCs) in extracts of wild chamomile flowers extracted by Ginsberg hydrodistillation, liquid-liquid extraction and dispersive liquid-liquid microextraction, as well as extraction under subcritical conditions and ultrasonic (US) treatment was carried out. Volatile compounds were identified by comparing the obtained mass spectra of the components with data from the NIST07 and WILEY8 databases. The contents of analytes in the extracts were estimated by internal normalization of peak areas and by the method of internal standard, as which thujone in acetone was used. VOC contents in essential oil and aromatic water obtained by Ginsberg hydrodistillation, under subcritical conditions and by ultrasonic treatment of acetone extracts from wild chamomile flowers were determined. As macrocomponents of the essential oil, β-Farnesene, α-bisabolol oxide B and bisabolol oxide A were identified. As macrocomponents of the hexane extract from aromatic water, α-Bisabolol oxide B, α-Limonene diepoxide, and bisabolol oxide A were identified. The main component of acetone extracts from wild chamomile flowers obtained under subcritical conditions and ultrasonic treatment was en-in-dicycloether. It was shown that the aromatic water of wild chamomile has higher content and wider list of VOCs in comparison with the essential oil.

Decomposition of thermally unstable analytes in the chromatograph injector is not uncommon in the practice of gas chromatographic analysis. However, as a rule, it cannot be detected by variations in the absolute areas of gas chromatographic peaks at different injector temperatures. This is hindered by the effects of area discrimination typical of sample dosing into capillary columns with flow division. The problem can be solved using relative peak areas calculated with respect to thermally stable compounds. Dependences of relative peak areas of unstable analytes on temperature (decreasing), as well as of their degradation products (increasing), are characterized by the presence of two limits. The low-temperature limits correspond to the real contents of unstable compounds or their degradation products in samples, and the high-temperature limits correspond to the composition of samples at hypothetically complete transformation of such analytes. Such dependences can be approximated by the logistic regression equation (otherwise – sigmoidal approximation or Boltzmann approximation). To test the applicability of logistic regression for processing the results of gas chromatographic analysis of thermally unstable compounds, the possibilities of approximating the temperature dependence of the peak areas of ethyldiazoacetate in various solvents were analyzed in the present work. The results confirm that gas chromatographic analysis of this ester and, apparently, of other diazocarbonyl compounds without their appreciable decomposition is possible at injector temperatures up to 200°C. The thermal destruction of ethyldiazoacetate in its solutions in aliphatic alcohols is accompanied by the formation of ethyl esters of alkoxyacetic acids – products of the introduction of intermediately formed ethoxycarbonylcarbene into the O–H bonds of alcohols. Such a characteristic of logistic regression as the value of the argument corresponding to the average value of the function indicates that the half-life temperatures of the initial analyte and “half-formation” of the products are the same, which makes it possible to correlate these processes with each other. A slight modification of the proposed method (addition of a point corresponding to the zero peak area at a hypothetical high injector temperature) makes it possible to extend it to characterize compounds with half-life temperatures higher than 300°C. Such a variant was used to test the thermal stability/instability of halogen derivatives of alkyl- and cycloalkylaromatic hydrocarbons under conditions of gas chromatographic analysis.