Extractive freezing-out as an easy-to-use and cheap method for a sample preparation in the determination of organochlorine pesticides in rice

Introduction. Despite efforts to find ecological methods for plant protection, the level of the use of chemical protection products are used very widely. Even after the establishment of the dangerous consequences of the use of organochlorine pesticides (OChPs), exclusion from the list of permitted pesticides in a number of countries, their production and use is still taking place. Information about the residual amounts of OChPs in food, as well as human biological tissues, is alarming. This represents a direct potential risk to human health.The purpose of the research is to develop a rapid gas chromatographic method for the determination of DDT, DDD, DDE and HCCH isomers in rice based on the extractive freezing-out as a sample preparation step.Materials and methods. The object of experimental study is grain rice, including one with OChPs additives. Gas chromatographic determination of toxicants was carried out after extractive freezing-out into a mixture of acetonitrile with ethoxyethane under the centrifugation of the sample (ECS) and by the sulfuric acid removal of co-extractives.Results. The efficiency of extraction of OChPs by the ECS method from rice grinding as the stage of sample preparation for gas chromatographic examination has been studied and confirmed. Purification with sulfuric acid is proposed for removing co-extractive components from the resulting extract. The results confirming the accuracy and low error in the determination of toxicants were obtained.Limitations. Grain rice was studied in the work. Rice products have not been studied.Conclusion. A technique has been created for the gas chromatographic determination of residual amounts of DDT, DDD, DDE, and HCCH isomers in rice with preliminary isolation of analytes by extractive freezing-out and sulfuric acid removal of co-extractive substances. The field of application of the development is sanitary and hygienic quality control of food products. The method provides the determination of OChPs in a sample weighing 3 g at a level below the established MPC with a relative error not exceeding 20%. Sample preparation is carried out at subzero temperatures. The procedure is simple, has a low cost, consumption of reagents, materials. The duration of the sample preparation stage is less than 1 hour.Compliance with ethical standards. The study does not require the conclusion of the biomedical ethics committee and other documents.Contribution: Bekhterev V.N. – concept and design of the study, planning and implementation of experimental studies, statistical processing of the array of results, analysis of literary data, discussion of the results and writing the manuscript of the article, approval of the final version of the text; Mishchenko I.V. – discussion of the results, editing, approval of the final version of the text; Komarova N.S. – approval of the final version of the manuscript of the article, responsibility for the integrity of all parts of the article. All authors are responsible for the integrity of all parts of the manuscript and approval of the manuscript final versionConflict of interest. The authors declare no conflict of interest.Acknowledgement. The study had no sponsorship.Received: October 6, 2024 / Revised: November 11, 2024 / Accepted: December 3, 2024 / Published: April 30, 2025

rice, organochlorine pesticides, extractive freezing-out, cryoextractor, chromatography