Fizer O. Potentiometric titrimetric systems based on analytical forms of cetylpyridinium

The thesis is concerned with the study of the reactions of the ionic association of cetylpyridinium with anions of different nature on the basis of which methods have been developed for the determination of certain lipophilic anions using potentiometric titration. IAs of cetylpyridinium with organic anions were synthesized and studied for the possibility of their use as electrode active substances in ion-selective electrodes sensitive to lipophilic ions. Using the methods of IR and NMR spectroscopy, the composition and structure of the synthesized AIs have been established. The composition of compounds is established by elemental analysis. Laboratory samples of ion-selective cetylpyridinium sensitive electrodes were manufactured, Were established their operational and metrological characteristics. The optimal conditions for the formation of the IA «cetylpyridinium-lipophilic anion» under conditions of potentiometric titration are established. Based on the behavior of titrimetric systems with the participation of CPC and the corresponding changes in potential, an extended series of lipophilicity (selectivity) of anions was obtained. A correlation was found between the value of the end-point potential beak and the HLI lipophilicity descriptors (R2 = 0,8974) and the logPo/w (R2 = 0,9069), which in turn makes it possible to predict the possibility of using the developed cetylpyridinium selective electrode for titration of various anionic forms. The theoretical model for calculating the logPo/w of anionic forms using the HLI descriptor has been clarified. HLI indices calculated on the basis of Ford-Wang charges correlate well with the logPo/w. The possibility of using the reactions of the ionic association of cetylpyridinium for the determination of anionic surfactants, phosphate and acid complexes of platinum and palladium was investigated. The appropriate methods of determination were developed, The proposed method allows determining about 20 mg/l of anionic surfactants (in terms of DDS) in wastewater. Simple methods for the determination of phosphates in soft drinks have been developed (Sr = 1-5%), The LQD of phosphate is 3×10-5 mol/l. The mixtures of [PtCl6]2- and [PdCl4]2- complexes can be analyzed with the mixed ratio from 1:4 to 4:1, in a concentration range of 10-3–10-5 mol/l.