Features of the behavior of the antibiotic tetracycline hydrochloride in the soil environment

Introduction. Pollution of the environment with tetracycline is caused by both emissions from pharmaceutical production and the introduction of antibiotic residues with manure as fertilizer, which requires the development of methods for cleaning, monitoring the content and studying the stability of the substance in the soil to reduce environmental risks. The study aims to investigate the stability of tetracycline and the determination of its transformation products in the soil environment. Materials and methods. Preparation of standard tetracycline solutions and their loading into the soil. Extraction of tetracycline from soil with EDTA-McIlwain buffer followed by purification by solid phase extraction. Analysis of extracts by chromatography with tandem mass spectrometry for quantitative and qualitative determination of the starting material and its transformation products. Comparative analysis of mass spectra of soil extracts to identify new decomposition products and assess the rate of degradation. Results. In soil, tetracycline undergoes gradual transformation with a half-life of 5–7 days for sod-podzolic soil and 8–12 days for chernozem; at the same time, decarboxamidation, deamination and dehydroxylation products accumulate, and researchers have also discovered previously undescribed compounds (m/z 679 and 701) with a suspected dimeric structure. Regardless of the type of soil, the composition of the transformation products was the same, which indicates similar mechanisms of antibiotic decomposition in different soil conditions. Limitations. The authors conducted the study in laboratory conditions using artificially contaminated soil samples, which may not fully reflect the complexity and diversity of real soil ecosystems and natural tetracycline transformation processes. They studied only two types of soil (sod-podzolic and chernozem), while in nature there is a much greater variety of soils with different physico-chemical properties that can significantly affect the rate and nature of the breakdown of the antibiotic. Experts identified the decay products only from mass spectrometric data without confirming their structure using additional methods (for example, NMR-spectroscopy), which leaves the possibility of erroneous interpretation of the composition of the products. Conclusions. Tetracycline decomposes rapidly in the soil to form new transformation products, including previously undescribed ones, which can significantly affect environmental safety and requires further study of their properties and consequences for the environment. Ethics. The study does not require the provision of an opinion from the biomedical Ethics Committee or other documents.