Syrotchuk O. Stationary chromatographic phases with reduced hydrophobicity in the determination of preservatives and active ingredients of anti-cold remedies by high performance liquid chromatography

The dissertation is devoted to the development of new methods and optimization of the determination of active pharmaceutical ingredients of high and medium polarity on stationary chromatographic phases (SCP), which have specific interaction centers using the method of high performance liquid chromatography. It has been shown that SCPs with propylonitrile groups (SiO2-CN) grafted to silica gel from different manufacturers are not the same in chromatographic properties, what is explained by the different structure and conformation of the grafted layer. SiO2-CN SCP have been identified that are close in properties, so it is advisable to use them to develop reliable methods for the determination of parabens. Due to the high polarity of SiO2-CN, it was possible to reduce the content of organic solvent in the mobile phase to 10% (v / v), which is 4-6 times less than when using SiO2-C18 NCP. Developed and validated express (up to 7 minutes) and eco-friendly method for the determination of methyl- and propylparaben for eight antitussive, anti-cold medicinal syrups. Stationary phase with pentafluorophenyl groups grafted to silica gel (SiO2-PFP) demonstrates the ability to specific dipole-dipole and π-π interactions, provides better retention and separation of polar aromatic acids. The lower hydrophobicity of SiO2-PFP in comparison with SiO2-C18 facilitates the rapid chromatography of organic bases and compounds of medium polarity. An isocratic method has been developed for the quantitative determination of compounds of different polarity, in particular, trimebutin, parabens, gallic and 4-hydroxybenzoic acids using SiO2-PFP. It has been shown that the optimal separation of polar components (paracetamol, phenylpropanolamine, caffeine) and the best symmetry of the peaks for organic bases (phenylpropanolamine, chlorpheniramine) are achieved using stationary phases with alkyl carbamate or alkylamide groups grafted to silica gel (SiO2-ACM, SiO2 -AAM). At the same time, these phases demonstrated a high degree of identity of SCPs from different manufacturers, in particular, the separation of the components was achieved in all the phases studied, the order of the compounds elution did not change in the pH range from 2.0 to 7.0. An express (up to 9 min) and eco-friendly method has been developed for the determination of paracetamol, caffeine, phenylpropanolamine, chlorphenylamine in anti-cold tablets using SiO2-ACM or SiO2-AAM SCP.