Oxidation of lipids and proteins occurs in food products with a high concentration of fat and water such as chilled meat and fish under the action of ionizing radiation, which leads to the formation of volatile organic compounds (VOCs) in the product and appearance of specific smell and taste. During storage, various biochemical processes occur in processed chilled products which also result in a change in the concentration of VOCs that affect the organoleptic properties of the product. The accumulation of volatile compounds identified in beef samples both immediately after radiation processing and within four days after irradiation is studied by gas chromatography–mass spectrometry to determine the effective dose range for the radiation processing of beef. Monitoring of the concentration of VOCs in samples of chilled beef meat irradiated with accelerated electrons with the energy of 1 MeV in a dose range of 0.25 to 5 kGy reveals explicit dependences of the concentrations of certain alcohols, aldehydes, and alkanes on the absorbed dose and storage time. The proposed mathematical model that describes the dependences of the concentrations of VOCs identified immediately after irradiation in beef samples on the irradiation dose is based on the simultaneous occurrence of two competing processes: decomposition of compounds due to their oxidation and accumulation due to the oxidation of other compounds after exposure to ionizing radiation. It is found on the basis of the results of the study that the effective dose range of radiation processing is 250 to 1000 Gy.

Radiation treatment of food makes it possible to solve some issues of the food industry, including suppression of pathogenic microbial contamination, retention of the nutritional value of the product, and increase in its shelf life. This treatment method in combination with highly sensitive methods of gas chromatography–mass spectrometry makes it possible to reveal biochemical markers of irradiation treatment in meat products with moderate fat content, such as chicken and turkey. This work describes the experimental results of the dependences of the content of volatile organic compounds in chilled chicken meat treated with 1 MeV accelerated electrons with the doses from 250 Gy to 20 kGy in two weeks of storage. The content of volatile organic compounds in irradiated and reference food samples has been determined on days 0, 1, 4, 6, 8, 11, and 13 after irradiation treatment. Similar behavior pattern of aldehydes identified in treated poultry meat, namely, hexanal, heptanal, and pentanal, has been determined in two weeks of product storage. An increase in the aldehyde concentration has been detected in samples treated with doses from 500 Gy to 10 kGy on days 1–4 after irradiation. It has been revealed that, with an increase in the irradiation dose the period of aldehyde accumulation in irradiated meat is displaced toward a shorter period of product storage. Thus, aldehydes can be considered as potential markers of irradiation treatment of chicken meat in the first four days after irradiation.

The need to develop safe methods for radiation processing of food products to improve their quality and extend their shelf life stimulates new scientific research aimed at increasing their effectiveness. Oxidation of lipids and proteins occurred under the impact of ionizing radiation in products with a high fat and water content, such as chilled meat and fish products, leads to the formation of volatile organic compounds in the product thus giving it a specific smell and taste. During storage, biochemical processes associated with microbial enzymatic activity and auto-oxidation develop in processed refrigerated products. These processes also modify the volatile organic compounds, which affect the organoleptic properties of the product. The method of gas chromatography-mass spectrometry was used to study the behavior of volatile compounds identified in irradiated beef samples both immediately after irradiation and four days later to determine the effective dose range for the radiation processing of beef. Monitoring of the content of volatile compounds in beef samples irradiated by 1-MeV electrons within a dose range from 0.25 to 5 kGy showed that the content of certain alcohols, aldehydes, and alkanes exhibited pronounced dose- and time-dependent character. The developed mathematical model describes the dependence of the concentration of volatile compounds identified immediately after irradiation in beef samples on the irradiation dose. The model is based on the simultaneous occurrence of two competing processes: the decomposition of compounds due to their oxidation and accumulation due to oxidation of other compounds after exposure to ionizing radiation. The results obtained revealed that the effective dosage range of radiation treatment lies between 250 and 1000 Gy.

Radiation treatment of food products carried out to increase their shelf life can result in chemical transformations initiated by free radicals. Volatile compounds (alcohols, aldehydes, ketones, etc.) formed, in particular, as a result of lipid oxidation, impair the organoleptic properties of products. Method of gas chromatography-mass spectrometry (GC-MS) makes it possible to identify the fact of food processing by detection of volatile marker compounds: in the case of meat products, the existing standard brings under regulation detection of 2-alkylcyclobutanones, however, the products with a reduced fat content, such as turkey and chicken, require an alternative marker. The results of GC-MS study revealed the dependence of microbiological parameters and the content of various volatile organic substances in chilled turkey meat on the dose of electron radiation. It is shown that the total amount of alcohols, ketones and aldehydes (11 compounds) decreases exponentially with an increase in the absorbed dose. An increase in the radiation dose leads to a higher content of carbonyl compounds (aldehydes and acetone), which results in a specific taste and smell of the irradiated products. At the same time, the acetone concentration increases linearly with the absorbed dose, which makes it possible to use acetone as a potential marker of the degree of irradiation of low-fat meat products. Irradiation in the “working” doses (0.5–1 kGy) significantly suppresses the pathogenic microflora and keeps the organoleptic properties of the product.

The necessity of developing safe methods of processing food products which improve the quality and extend their shelf life entails further scientific research aimed at increasing the efficiency of radiation processing of food products. Ionizing radiation causes lipid peroxidation in the items with a high fat and water content, such as chilled meat and fish products, which leads to formation of organic volatile compounds that render the food the specific flavor and smell. Gas chromatography-mass spectrometry is a technique that provides identification of chemical changes that actually occur in the product after irradiation. Experimental data on the content of organic volatile compounds in chilled turkey and salmon meat samples exposed to irradiation with 1 MeV accelerated electrons in the dose range from 0.25 to 2 kGy revealed both common and different trends in the behavior of dose dependences of alcohol, aldehyde and ketone contents in various types of chilled products. A proposed mathematical model based on the possibility of simultaneous occurrence of two competing processes, i.e., the decomposition of compounds due to their oxidation and the accumulation of compounds due to oxidation of other compounds after exposure to ionizing radiation match a dose dependent character of experimental data.

A method of food radiation treatment can address a number of problems in the food industry, including the suppression of pathogenic microbial contamination, preservation of the nutritional value of the prod­uct, and extension of the food shelf life. When combined with a highly sensitive gas chromatography-mass spectrometry, the method provides detection of biochemical markers of radiation processing in meat prod­ucts with a low content of fat, such as chicken and turkey. We present the results of studying the depend­ ence of the content of volatile organic compounds in chilled chicken meat treated with 1 MeV accelerated electrons in a dose range from 250 Gy to 20 kGy during two weeks of storage. Concentrations of volatile organic compounds in the irradiated and control samples of food samples were determined on the zeroth, 1 st , 4 th , 6 th , 8 th , 11 th and 13 th days after irradiation. Concentrations of aldehydes, namely, hexanal, heptanal, and pentanal identified in poultry meat samples exposed to radiation demonstrated a similar behavior during two weeks of product storage. Samples exposed to irradiation in a dose range from 500 Gy to 10 kGy exhibited an increase in the aldehyde content on days 1-4 after irradiation. It is shown that the time of aldehydes accumulation in irradiated meat shifts towards a shorter period of the product storage with an increase in the dosage of irradiation. Thus, aldehydes can be considered potential markers of the radiation treatment of chicken meat during the first four days after irradiation.

A green, scalable, and sustainable approach to prepare aqueous fullerene dispersions (AFD) C60, C70, endohedral metallofullerene Gd@C82, and their derivatives C60Cl6, C70Cl10, and supramolecular and ester-like derivatives, 10 fullerene species total, is proposed. For the first time, an immersed ultrasonic probe was used to preparing dispersions for pristine fullerenes without addends. Both ultrasound-assisted solvent-exchange and direct sonication techniques for AFD preparation using an immersed probe were tested. The average time for AFD preparation decreases 10?15 times compared to an ultrasound-bath-assisted technique, while final fullerene concentrations in AFDs remained at tens of ppm (up to 80 ppm). The aqueous dispersions showed long-term stability, a negatively charged surface with a zeta potential up to ?32 mV with an average nanocluster diameter of no more than 180 nm. The total anionic and cationic compositions of samples were found by inductively coupled plasma atomic emission spectroscopy and chromatographic techniques. The highlights and challenges of using an ultrasound probe for AFD production are discussed.

A method for identifying straits of rocket kerosene (RG-1 and T-1 brands) and various types of hydrocarbon fuels (aviation fuel TC-1 and diesel fuel) in soil has been developed. The proposed version of identification is based on the preliminary separation of the main components by gas chromatography and their mass spectrometric detection followed by the processing of the data obtained by chemometric methods of analysis (principal component analysis and projection on latent structures with discriminant analysis) using the “MZmineZ,” “iMet-Q,” and “MetaboAnalyst” software. A possibility of the application of the developed approach to the typification of saturated oil fractions of different origin is illustrated.

A possibility of the identification of semi-volatile hydrocarbon fuels in soil samples by studying the distribution of biomarkers of the sesquiterpane class is shown. The extraction of a soil sample with methylene chloride and the subsequent analysis of the extract by gas chromatography–mass spectrometry ensured the detection of these hydrocarbons in RG-1 and T-1 rocket kerosenes, TS-1 aviation kerosene, and diesel fuel. It was found that the distribution of the compounds found is characteristic for each type of fuel and is preserved in their transformations in the soil. The parameters reflecting the distribution of biomarkers and ensuring the identification of the type of fuel at any stage of transformation are proposed.

The ultrasound-assisted solvent-exchange technique for aqueous fullerene dispersions (AFD) of C-60 (10(-4) - 10(-6) M) have been improved for high-yield synthesis, thereby achieving AFDs with total recovery over 90 %. Using ICP-AES, HPLC-UV, HGC-MS, the elemental and residual organic compounds have been estimated as not exceeding 3 ppm. The possible structure of fullerene clusters in AFD was assumed as {n[C-60]mC(6)H(5)COO(-) (m - x)Na+}xNa(+).

Разработан способ идентификации проливов в почве ракетных керосинов (марок РГ-1 и Т-1) и близких к ним по физико-химическим свойствам углеводородных топлив (авиационного керосина марки ТС-1 и дизельного топлива). В основу предложенного варианта идентификации входит предварительное разделение основных компонентов методом газовой хроматографии и их масс-спектрометрическое детектирование, а также обработка полученных данных с помощью хемометрических методов анализа (метода главных компонент и дискриминационного анализа с помощью регрессии на латентные структуры) с помощью программ «MZmine2», «iMet-Q» и «MetaboAnalyst». Проиллюстрирована возможность применения разработанного подхода для типизации насыщенных фракций нефтей, имеющих различное происхождение. A method for identifying straits of rocket kerosene (RG-1 and T-1 brands) and various types of hydrocarbon fuels in the soil (aviation fuel ТС-1 and diesel fuel) has been developed. The proposed variant of identification is based on the preliminary separation of the main components by gas chromatography and their mass spectrometric detection, and processing of the obtained data with chemometric methods of analysis (principal component analysis and projection on latent structures with discriminant analysis) using the programs "MZmine2", "iMet-Q" and "MetaboAnalyst". The opportunity of application of the developed approach for the typification of saturated fractions of oils from different origins is illustrated.

A simple method for the determination of 16 priority polycyclic aromatic hydrocarbons (PAHs) from geological cores as oil markers using microemulsion extraction, pre-concentration with following fluorometric detection was developed. Parameters, such as the composition of microemulsion (ME), temperature, pH, which affect the intensity of fluorescence were investigated and optimized. The potential of the developed technique has been demonstrated by the determination of these PAHs in oil and oil cores. The calculated pre-concentration factor using microemulsion (3.3% CTAB, 0.8% heptane, 8% n-butanol and 87.9% water) varies from 5 to 10. The main parameters that influence the intensity of fluorescence are the charge of a surfactant and the nature of the oil. The limits of detection ranged between 10-50 mu g/kg. [GRAPHICS] .

The solvent-exchange process from toluene was used for preparing aqueous dispersions of C60 and C70 without preconcentration with final concentrations of 180 ± 2 and 62 ± 1 μM, respectively, which exceeds the previously reported maximum concentrations for C60 more than 6-fold; for C70 such an aqueous dispersion is prepared for the first time. The residual quantity of the organic solvent and low-molecular compounds determined by headspace GC-MS was not more than 1 ppb. The procedure for the determination of fullerenes in aqueous dispersions is developed using a total organic carbon analyzer and absorption spectra; LOD, 50 nM, LOQ, 200 nM by TOC. Spectrophotometric determination of fullerenes in their aqueous dispersions was optimized: for C60 at 268 nm: LOD, 0.1 μM, LOQ, 0.3 μM, for C70 at 218 nm: LOD, 0.1 μM, LOQ, 0.3 μM. RSD mixture quantification by Vierordt’s method in the range of 2 – 20 μM does not exceed 0.14 for C60 and 0.09 C70. RSD for toluene fullerene mixtures by Vierordt’s method in the range of 2 – 20 μM does not exceed 0.10 for C60 and 0.06 for C70.

A procedure for sensitive determination of rocket kerosene in water is described; it includes the dispersive liquid–liquid microextraction of analytes followed by their separation and determination by gas chromatography mass spectrometry in the mode of chromatogram registration against selected ions (m/z: 67, 81, 85, 95, 136, 137, 174, 183, and 193). The effect of the nature and volume of disperser and extraction solvents, salt additives, and the extraction duration on the efficiency of extraction of analytes is studied. The detectable concentration range is 0.005–0.05 mg/L. The detection limits (S/N = 3) of kerosene RG-1 and T-1 are 0.0015 and 0.0022 mg/L, respectively. The repeatability of the measurement results for the above range varies from 16 to 9% (n = 3); the intermediate precision varies from 20 to 12% (n = 5).

A method has been developed for determining rocket kerosene (RG-1 and T-1) in soil by static headspace analysis with subsequent gas chromatography–mass spectrometry analysis. It has been shown that the headspace analysis of a solid sample is the preferred approach to sample pretreatment compared with the ultrasonic extraction by methanol and the analysis of the equilibrium headspace collected above the extract. The effects of the temperature, the incubation time of the sample, and the moisture of the sample on the extraction and the sensitivity of the headspace determination of rocket kerosenes in soils of different nature have been considered. It has been found that 1 cm 3 of the headspace collected above the sample at the temperature of 90°C for 20 min should be injected into a chromatograph (splitless injection mode) to determine the mass concentration of kerosenes in soil in the range of 50–500 mg kg –1 . To determine the concentration in the range of 500–20000 mg kg –1 , 0.1 cm 3 of the headspace collected under similar conditions should be injected into a chromatograph (split mode, 1: 10). The repeatability of the measurements for the studied concentration ranges is 12–6% and the intermediate precision is 14.3–7.4%. The gas chromatography analysis takes 41 min.

Anew approach to determination of semi-volatile hydrocarbon fuels in plants grown on the soils contaminated by the aforementioned fuel is developed on the example of aviation kerosene. The method is based on ultrasonic methanol pre-extraction of the analyzed compounds followed by static headspace analysis and gas chromatography-mass spectrometry determination. Chromatograms were registered in selected ion monitoring mode (SIM), m/z 57 and 142. The calculated detection limit for aviation kerosene is 1 mg/kg of dry weight of green plants, the detectable concentrations range within 3 - 500 mg/kg of dry weight.