Determination of thermodynamic acidity constants and limiting ionic mobilities of weak electrolytes by capillary electrophoresis using a new free software AnglerFishThermodynamic acidity constants (acid or acid-base dissociation constants, sometimes called also as ionization constants) and limiting ionic mobilities (both of them at defined temperature, usually 25°C) are the fundamental physicochemical characteristics of a weak electrolyte, that is, weak acid or weak base or ampholyte. We introduce a novel method for determining the data of a weak electrolyte by the nonlinear regression of effective electrophoretic mobility versus buffer composition dependence when measured in a set of BGEs with various pH. To correct the experimental data for zero ionic strength we use the extended Debye-Hückel model and Onsager-Fuoss law with no simplifications. Contrary to contemporary approaches, the nonlinear regression is performed on limiting mobility data calculated by PeakMaster's correction engine, not on the raw experimental mobility data. Therefore, there is no requirement to perform all measurements at a constant ionic strength of the set of BGEs. We devised the computer program AnglerFish that performs the necessary calculations in a user-friendly fashion. All thermodynamic pKa values and limiting electrophoretic mobilities for arbitrarily charged substances having any number of ionic forms are calculated by one fit. The user input consists of the buffer composition of the set of BGEs and experimentally measured effective mobilities of the inspected weak electrolyte.

Beta-blockers are chiral compounds with enantiomers that have different bioactivity, which means that while one is active, the other can be inactive or even harmful. Due to their high consumption and incomplete degradation in waste water, they may reach surface waters and affect aquatic organisms. To address this issue we developed a chromatographic method suitable for determining beta-blocker enantiomers in surface waters. It was tested on five beta-blockers (acebutolol, atenolol, bisoprolol, labetalol and metoprolol) and validated on bisoprolol enantiomers. Good enantioseparation of all analysed beta-blockers was achieved on the Chirobiotic V column with the mobile phase composed of methanol/acetic acid/triethylamine (100/0.20/0.15 v/v/v) at a flow rate of 0.5 mL/min and column temperature of 45 °C. Method proved to be linear in the concentration range from 0.075 µg/mL to 5 µg/mL, and showed good recovery. The limits of bisoprolol enantiomer detection were 0.025 µg/mL and 0.026 µg/mL and of quantification 0.075 µg/mL and 0.075 µg/mL. Despite its limitations, it seems to be a promising method for bisoprolol enantiomer analysis in surface water samples. Further research could focus on waste water analysis, where enantiomer concentrations may be high. Furthermore, transferring the method to a more sensitive one such as liquid chromatography coupled with tandem mass spectrometry and using ammonium acetate as the mobile phase additive instead of acetic acid and triethylamine would perhaps yield much lower limits of detection and quantification.

Praziquantel (PZQ) is a biopharmaceutical classification system (BCS) class II anthelmintic drug characterized by poor solubility and a bitter taste, both of which can be addressed by inclusion complexation with cyclodextrins (CD). In this work, a comprehensive investigation of praziquantel/cyclodextrin (PZQ/CD) complexes was conducted by means of UV–vis spectroscopy, spectrofluorimetry, NMR spectroscopy, liquid chromatography-high-resolution mass spectrometry (LC-HRMS/MS), and molecular modeling. Phase solubility studies revealed that among four CDs tested, the randomly methylated β-CD (RMβCD) and the sulfobutylether sodium salt β-CD (SBEβCD) resulted in the highest increase in PZQ solubility (approximately 16-fold). The formation of 1:1 inclusion complexes was confirmed by HRMS, NMR, and molecular modeling. Both cyclohexane and the central pyrazino ring, as well as an aromatic part of PZQ are included in the CD central cavity through several different binding modes, which exist simultaneously. Furthermore, the influence of CDs on PZQ stability was investigated in solution (HCl, NaOH, H 2 O 2 ) and in the solid state (accelerated degradation, photostability) by ultra-high-performance liquid chromatography–diode array detection–tandem mass spectrometry (UPLC-DAD/MS). CD complexation promoted new degradation pathways of the drug. In addition to three already known PZQ degradants, seven new degradation products were identified ( m / z 148, 215, 217, 301, 327, 343, and 378) and their structures were proposed based on HRMS/MS data. Solid complexes were prepared by mechanochemical activation, a solvent-free and ecologically acceptable method.

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