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Adsorption mechanisms of caffeine, quercetin, and phenol as test substances in various chromatographic systems have been analyzed. The investigations were conducted using three different chromatographic columns packed with polar bonded stationary phases, that is, amide, amine, and zwitterionic. Methanol–water and acetonitrile–water systems with different organic solvent contents have been used as mobile phases. On the basis of adsorption isotherms obtained for the tested systems, Scatchard plots and adsorption energy distributions have been determined. The most likely retention mechanisms have been discussed. The results of investigations indicate that (i) the surfaces of tested adsorbents are energetically heterogeneous, and (ii) the main role in sorption mechanism is played by low‐energy sites.

The main purpose of the research was to obtain and study hybrid materials based on three different nano-oxides commonly used in the cosmetic and pharmaceutical industries: Al2O3, TiO2, and ZnO, with the natural bioactive polysaccharide fucoidan. Since the mentioned oxides are largely utilized by industry, there is no doubt that the presented studies are important from an environmental point of view. On the basis of the textural studies (dynamic light scattering DLS, low temperature nitrogen adsorption, X-ray diffraction analysis XRD, scanning electron microscopy SEM) it was proved that the properties of the hybrid materials differ from the pure components of the system. Moreover, the advanced thermal analysis (TG-DTG-DSC) combined with the evolved gas analysis using Fourier transformed infrared spectroscopy (FTIR) and mass spectrometry were applied to describe the thermal decomposition of fucoidan, oxides and hybrid materials. It was found that the interactions between the polymer and the oxides results in the formation of the hybrid materials due to the functionalization of the nanoparticles surface, and that their thermal stability increased when compared to the pure substrates. Such findings definitely fill the literature void regarding the fucoidan based hybrid materials and help the industrial formulators in the preparation of new products.

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The coordination ability of QSA− ligand towards potassium cations was investigated. Potassium complex of quercetin-5’-sulfonate of the general formula [KQSA(H2O)2]n was obtained. The [KQSA(H2O)2] (1) was a starting compound for solvothermal syntheses of acetone (2) and dimethylsulfoxide (3) complexes. For the crystalline complexes 1–3, crystals morphology was analyzed, IR and Raman spectra were registered, as well as thermal analysis for 1 was performed. Moreover, for 1 and 3, molecular structures were established. The potassium cations are coordinated by eight oxygen atoms (KO8) of a different chemical nature; coordinating groups are sulfonic, hydroxyl, and carbonyl of the QSA− anion, and neutral molecules—water (1) or DMSO (3). The detailed thermal studies of 1 confirmed that water molecules were strongly bonded in the complex structure. Moreover, it was stated that decomposition processes depended on the atmosphere used above 260 °C. The TG–FTIR–MS technique allowed the identification of gaseous products evolving during oxidative decomposition and pyrolysis of the analyzed compound: water vapor, carbon dioxide, sulfur dioxide, carbonyl sulfide, and carbon monoxide. The solubility studies showed that 1 is less soluble in ethanol than quercetin dihydrate in ethanol, acetone, and DMSO. The exception was aqueous solution, in which the complex exhibited significantly enhanced solubility compared to quercetin. Moreover, the great solubility of 1 in DMSO explained the ease of ligand exchange (water for DMSO) in [KQSA(H2O)2].