Express-determination of organochlorine pesticides in water by method of extractive freezing-out in combination with gas chromatography

Introduction. Special attention is paid to the control of the purity of water resources. Pollution by the aquatic medium with organochlorine pesticides (OChPs) and their metabolites still remains a serious problem. The determination of toxicants in water, and even more so, contaminated with household and industrial wastewater, is complicated by the need for additional preliminary sample preparation for the stage of physical-chemical research.

The purpose of the research is to develop a rapid method for determining OChPs using innovative technology for the isolation of organic compounds.

Materials and methods. The objects of experimental study were model aqueous solutions of dichlorodiphenyltrichloretan (DDT), dichlorodiphenyldihloromethylmethane (DDD), dichlorodiphenyldihlorethylene (DDE), hexachlorobenzene (HCB), and hexachlorocyclohexane (HCCH) isomers and real objects. The determination of toxicants in drinking, marine, and sewage household water was carried out by extractive freezing-out (EF) into ethoxyethane in combination with gas chromatography.

Results. The efficiency of extraction of OChPs by the EF method from water at the stage of sample preparation for gas chromatographic examination has been studied and confirmed. The results confirming the accuracy and low error in the determination of toxicants were obtained.

Limitations. The pH range of the studied aqueous mixtures was from 3 to 7. It was previously established that in an alkaline medium there is a noticeable concentration decrease of some analytes over time, which requires additional study.

Conclusion. A technique of the preliminary isolation of analytes by extractive freezing-out with subsequent gas chromatographic determination has been developed. The application field of the development is sanitary and hygienic control of the water quality. The method provides the determination of OChPs in a sample volume of 10 ml at a level below the established MPC with a relative error not exceeding 20%. Sample preparation is carried out in one step without any additional manipulations with the sample at subzero temperatures, which is favourable for improving working conditions and safety, since the volatility of solvents and components of the test sample is significantly reduced. The procedure is simple, there are no additional requirements for the qualification of a operator. It has a low cost, consumption of reagents and materials. The duration of the sample preparation stage does not exceed 30 minutes.

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.

Conflict of interest. The authors declare no conflict of interest.

Acknowledgement. The study had no sponsorship.

Received: March 18, 2024 / Accepted: April 9, 2024 / Published: June 17, 2024

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