Khalaf V. Sorption pre-concentration and determination of phenol, 1-naphthole and 2,4,6-trinitrophenol using chemically modified silicas

The Ph. D. thethis is devoted to investigation of chemically modified silicas containing groups of aryldiazonium salts, 2,3,5-triphenyltetrazole and Triton X-100. Phenols hold an important place among organic pollutants, which need to be constantly monitored in waters and in places of military activities. Sampling of phenol matrix is conducted with solid phase extragents (SPE) with further high performance liquid chromatography or gas chromatogra-phy analysis. Application of the known SPE usually is ineffective as it doesn't give the possibility to provide full extraction of the analyt (microcontents) in the matrix media. Therefore SPE application needs further progress in their selectivity. In the stated work was proposed a rate of modified silicas for extraction of activated and deactivated phenols. Two methods were proposed for extraction of the activated phenols. The first approach is based on heterogeneous azo-coupling reaction of phenols with aryldiazonium salts bonded on the silica surface. Forthis purpose p-aminoacetophenone and m-aminophenilarsonic acid were used. First reagent was covalently bonded on the silica, while second was bonded by the ion-exchange on the silica with covalently grafted quaternary ammonium salt. These diazo-couplers were transferred into aryldiazonium salts, which were stabilized with potassium tetrafluoroborate and were azo-coupled with phenols in aqua media. Complete adsorption of 1-naphthol, 2-naphthol, and resorcinol from water takes place at pH 6-9, while phenol and pirocatechin react with immobilized aryldiazonium salts at pH 8-9. In both of the de-scribed methods formation of immobilized azo-compounds as a result of SPE reaction with phenol leads to a drastic change in the sorbent's color. The second approach is based on a direct interaction of phenols with 4-nitrophenyldiazonium tetrafluoroborate in aqua media and its further extraction by modified silica with polyoxyethylene isooctylphenol groups in the presence of cationic surfactant. The capacity of silicas containing groups of Triton X-100 to phenol is up to 25 ?mol/g. Rapid determination of activated phenols in water by combined solid-phase extraction - diffuse reflectance spectroscopy was developed for sili-cas with aryldiazonium salts groups and polyoxyethylene isooctylphenol silica. Azo-dyes of phenol and 1-naphthole on polyoxyethylene isooctylphenol silica surface allowed to de-velop simple procedure for their desorption with further liquid chromatography/mass spec-trometry or photometric analysis. For the selective pre-concentration of deactivated phenols a new silica-based material with the grafted 2,3,5-triphenyltetrazole was proposed. This method is based on the forma-tion of molecular charge-transfer complexes of 2,3,5-triphenyltetrazole ( -donor) with pic-ric acid ( -acceptor) in the phase of the adsorbent. Proposed SPE is suitable for high performance liquid chromatography or photometric analysis of 2,4,6-trinitrophenol after its desorption by acetonitrile.