The research consisted of investigation of non-freezable bound water (NFW) contents of raw hydroxypropylcellulose (HPC) Klucel^® Pharm HF, MF, and LF by differential scanning calorimetry. Polymers (HF, MF and LF) used in the research differed significantly in their molecular mass and viscosity. Mixtures of HPC and low soluble salicylic acid or highly soluble sodium salicylate were used to examine the effect of counter-ions presence and drug solubility on NFW contents. The dependencies of determined enthalpies of melting (ΔH) and respective contents of water W_c (water fraction in the dry mass of HPC or HPC mixture) ΔH = f(W_c) were linear. The sought values of non-freezing water were calculated (by extrapolation) as the concentration at which ΔH = 0. It was found that the viscosity and molecular mass of the raw HPCs did not affect the contents of non-freezing water, which ranged between 0.54 and 0.51 g g⁻¹ for all types LF, MF, HF. Poorly soluble salicylic acid (SA) reduced the non-freezing water content to 0.19–0.17 g g⁻¹. On the other hand, matrices composed of highly soluble sodium salicylate (NaSA) showed variable decrease of NFW content—0.44 g g⁻¹ for HF and 0.54–0.51 g g⁻¹ for LF and MF. It was also found that the maximum temperature T_max of melting was strongly influenced by the solubility of the drug. Highly soluble NaSA shifted T_max toward the lower negative values, while SA toward the higher positive values. Assessing NFW contents in hydrated HPC matrices may contribute to a better understanding of the drug release and dissolution mechanisms of tablet formulations.

Ciprofloxacin (CIP), moxifloxacin (MOX), norfloxacin (NOR) and ofloxacin (OFL), are the antibacterial synthetic drugs, belonging to the fluoroquinolones group. Fluoroquinolones are compounds susceptible to photodegradation process, which may lead to reduction of their antibacterial activity and to induce phototoxicity as a side effect. This paper describes a simple, sensitive UPLC-MS/MS method for the determination of CIP, MOX, NOR and OFL in the presence of photodegradation products.

Methylxanthines (caffeine, theophylline, theobromine) are a popular group of natural purine alkaloids, which are components of many commonly used drugs, parapharmaceuticals and a wide range of food products (e.g. coffee, tea, energy drinks, etc.). Caffeine metabolites (theophylline, paraxanthine, theobromine and other 1-, 3-, 7-methyl tri-, di- and mono-derivatives of xanthine) and hypoxanthine metabolites (xanthine, uric acid) play an important role in the biochemical processes of mammalian organisms. That is why they are the markers of many diseases and are in the focus of the clinicians, pharmaceutical industry and ecologists. In addition to the natural methylxanthines there are structurally related synthetic derivatives: pentoxifylline, dyphylline, xantinol nicotinate and 8-chlorotheophylline that are still valuable pharmaceuticals needing to be monitored. A review of the modern techniques used for determination of methylxanthines for the last 10 years (2000 – March 2010) is presented.

The aim of the study was to calculate the content of non-freezing water (NFW) as well as amount of water associated with the evaporation process (N_ev) in the chosen species of fungi. The study focused on lyophilized in vitro mycelium and commonly cultivated mushrooms Agaricus bisporus, Boletus badius and Cantharellus cibarius. Both NFW and N_ev were examined by means of differential scanning calorimetry (DSC). The above-mentioned types of water are important components of the state diagram that is a kind of functional graph helping in identifying food stability during storage and selecting suitable conditions of temperature and moisture content for processing. The content of non-freezing water in all examined samples ranged between 0.19 and 0.31 g g⁻¹. The estimated amount of water associated with the evaporation process was found to be between 0.05 and 0.13 g g⁻¹. The obtained results were variable and highly dependent on fungus species, origin (in vitro mycelium vs cultivated) and content of accumulated metals. The influence of these factors is discussed. In order to determine statistical significance, selected samples were measured at least 5 times; the relative standard of deviation (%RSD) did not exceed 4.45 of measured enthalpies. In the group of mycelium from in vitro cultures, the DSC method was used for the first time. The publication also compared the NFW and N_ev values with those obtained for naturally grown fruiting bodies of the same species.

Differently bound water molecules confined in hydrated hydroxypropyl cellulose (HPC) type MF and their mixtures (1:1 w/w) with lowly soluble salicylic acid and highly soluble sodium salicylate were investigated by differential scanning calorimetry (DSC). The obtained ice-melting DSC curves of the HPC/H₂O samples were deconvoluted into multiple components, using a specially developed curve decomposition tool. The ice-melting enthalpies of the individual deconvoluted components were used to estimate the amounts of water in three states in the HPC matrix: free water (FW), freezing bound water (FBW), and non-freezing water (NFW). A search for an optimal number of Gaussian functions was carried out among all available samples of data and was based on the analysis of the minimum fitting error vs. the number of Gaussians. Finally, three Gaussians accounting for three fractions of water were chosen for further analysis. The results of the calculations are discussed in detail and compared to previously obtained experimental DSC data. AI/ML tools assisted in theory elaboration and indirect validation of the hypothetical mechanism of the interaction of water with the HPC polymer.

The aim of the study was to examine the influence of non-freezing water (NFW) contents bound to hydroxypropyl methylcellulose (HPMC) or hydroxypropyl cellulose (HPC) binary mixtures using...