Features of the gas chromatographic method for monitoring the content of phenols in an aqueous medium

Abstract

THE RELEVANCE. Phenols are one of the main pollutants of the aquatic environment and have a harmful effect on the human body. Therefore, their determination today is an urgent problem. The purpose of this work is to determine the content of phenols in an aqueous medium by gas chromatographic method using various sorption materials. To do this, it is necessary to consider some features of the gas chromatographic method for monitoring the content of phenols in an aqueous medium using various sorption materials. Based on a detailed literature review to show that phenols and their derivatives are highly toxic substances, have low values of MPC standards, ha\’e a negative impact on the human body, which necessitates their control in the aquatic environment. METHODS. To determine phenols in an aqueous medium, the experimental part of the work was carried out on a Crystallux-4000M gas-liquid chromatograph with a flame ionization detector and nozzle columns filled with various sorbents, as which polyethylene glvcol-1500, SE-30 and arsenated polyethylene glycol PEG(As) were used. RESULTS. For gas chromatographic separation of phenols and their derivatives, sorption materials of various physicochemical nature were used. It has been established that the most optimal sorbent, which separates almost all phenols and their derivatives, is polyoxyethylene bis arsenate, the molecule of which contains two arsenvl groups capable of intermolecular interactions with the analyzed sorbates. CONCLUSION. An experimental study of the phenol content in an aqueous medium using a gas-liquid chromatograph Crystallux-4000M was carried out. The characteristics of the retention of phenols on sorption materials of different physicochemical nature are determined. It is shown that the most complete separation of the individual components of phenol derivatives is carried out on a sorbent prepared on the basis of polyoxyethylene bis arsenate, which is explained by the presence in the structure of its molecule of non-white electron pairs of oxygen atoms capable of intermolecular interactions with the hydroxyl group of phenols. The linear dependence of the logarithm of the relative volume of phenols on their dipole moments and refractive index is established. A deviation from this dependence is obsen’ed for phenols having functional substituents in the ortho-position of the benzene ring. This can be explained by the electronic effect? which leads to steric difficulties during intermolecular interaction in the sorbent - sorbate system. Based on the theoretical studies carried out, it was possible to completely separate the individual components of phenols, especially those with close boiling points. The obtained data were tested in practice when monitoring the content of phenols in the silt drains of the Volga river. This technique of gas chromatographic analysis can be used in the system of ecological monitoring of aquatic ecosystems.

Keywords

• phenols
• sorption materials
• arsenated polyethylene glycol
• gas chromatography
• retention time
• separation