The graduate qualification work of Fedorova A.V. is devoted to the development of a fast method of extraction and preconcentration of mycotoxin (ochratoxin A) from food products with preliminary extraction of analyte from solid sample into ammonia solution and subsequent formation of isotropic solution by adding amphiphile to the neutralised extract. In this work, a new approach to micelle-mediated microextraction was implemented, involving in situ formation of n-octylamine citrate (during the reaction of the primary amine with citric acid), acting as a cationic surfactant, followed by preconcentration of ochratoxin A from the aqueous extract of the food sample into the supramolecular solvent phase by the introduction of a coacervation agent, tetrabutylammonium bromide. The extraction system was thoroughly characterised. The separation of the solvent in the lower part of the system allowed its crystallisation and separation of the aqueous phase by decantation, and the alkaline nature of the obtained extract made it possible to use acetic acid instead of more toxic organic solvents for its dissolution.
In order to achieve the highest values of extraction characteristics (extraction recovery and enrichment factor) based on the analysis of experimental data, the conditions of micellar liquid-liquid microextraction and separation of ochratoxin A from the matrix of food product were selected and optimised. Fedorova A.V. validated the developed method with achievement of positive results (which provides reliable determination of the analyte at the level of maximum permissible concentrations in food products in accordance with the requirements of regulatory documents), and also illustrated its capabilities for determination of the analyte in samples of corn, millet and barley cereals. In the course of research the physicochemical properties of the supramolecular solvent phase were established and the composition of the extraction system was determined by gas chromatography-mass spectrometry, capillary electrophoresis with spectrophotometric detection and coulometric Karl Fischer titration. According to the data obtained, conclusions were drawn about the key role of tetrabutylammonium bromide and citric acid in micelle formation and preconcentration of the analyte, their uniform distribution between the sample and supramolecular solvent phases, and the formation of fully substituted amine citrate in the extraction system.
The results of the research were published in the highly rated international peer-reviewed journal ‘Analytica Chimica Acta’ (I quartile, IF 6,2). Also, Fedorova A.V. presented the results of the work done in the form of an oral report at the XXVI All-Russian Conference of young scientists-chemists (Nizhny Novgorod. 2022), and in the form of abstracts at the grant competition for students of universities located in St. Petersburg, graduate students of universities, branch and academic institutes located in St. Petersburg in 2024 on the topic of research conducted in the framework of this work. During her work, including as a laboratory researcher under the RSF grant № 21-13-00020, Anastasia Viktorovna has shown herself as a hardworking, responsible and accurate employee.
The graduate qualification work of Fedorova Anastasia is characterised by originality and has practical significance, and the identified textual coincidences in the Blackboard system (12.28 % of borrowings) are due to the technical nature and are associated with the use of commonly used terms, concepts, turns, names of chemical reagents.
Based on the above, I believe that the final qualification work of Fedorova A.V. deserves the grade ‘excellent’, ‘A’ (according to the ECTS system).