Higher lipophilicity facilitates the passage of a substance across lipid cell membranes, the blood–brain barrier and protein binding, and may also indicate its toxicity. We proposed eight methods for predicting the lipophilicity of the 22 most commonly used organophosphate pesticides. In this work, to determine the lipophilicity and thermodynamic parameters of the solvation of pesticides, we used methods of density functional theory with various basis sets, as well as modern Grimm methods. The prediction models were evaluated and compared against eight performance statistics, as well as time and RAM used in the calculation. The results show that the PBE-SVP method provided the best of the proposed predictive capabilities. In addition, this method consumes relatively less CPU and RAM resources. These methods make it possible to reliably predict the ability of pesticide molecules to penetrate cell membranes and have a negative effect on cells and the organism as a whole.

We report a comprehensive investigation of Cu(II) and Pb(II) ion sorption kinetics on magnetically functionalized Ti₃C₂T_x MXene composites. The composite material was synthesized by functionalizing multilayer MXenes with iron oxide nanoparticles through a co-precipitation method, resulting in a magnetic sorbent with a saturation magnetization of 32 ± 3 A m²/kg. The experimental data were analyzed using pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. The sorption process for both metal ions followed pseudo-second-order kinetics (R² > 0.99), with activation energies of –61.5 and ‒24.8 kJ/mol for Cu(II) and Pb(II), respectively. The analysis revealed that Cu(II) sorption involves both chemical interactions with functional groups and diffusion processes, while Pb(II) sorption is primarily diffusion-controlled. External diffusion rates were found to be an order of magnitude higher than internal diffusion rates for both metal ions, suggesting that the 2D structure of MXenes may influence the intraparticle diffusion of heavy metals. The magnetic functionalization enables efficient separation of the sorbent after treatment, making this composite material promising for heavy metal removal applications in water treatment processes.

The technology for manufacturing a film membrane of the metamizole-selective electrode containing ion associate metamizole-octadecylammonium ODAH${}^{+}$MT${}^{-}$ as an electrode active component (EAC) has been proposed. The main potentiometric characteristics of the metamizole-selective electrode have been determined. The expediency of the proposed design of the metamizole selective electrode for the determination of metamizole in dosage forms has been substantiated. The best composition of the membrane (wt.%) of the metamizole-selective electrode has corresponded to: ODAH${}^{+}$MT${}^{-}$—5.3; 2-nitrophenyloctylether—63.1; poly(vinyl chloride)—31.6. Electrode-active component in the membrane phase functions as an ion associate ODAH${}^{+}$MT${}^{-}$. Potentiometric characteristics of metamizole-selective electrode have been determined, which corresponded to: linear range 1 × 10${}^{-2}$–1 × 10${}^{-4}$ with limit of detection 4.58 × 10${}^{-5}$ M, electrode function slope −48.5 mV/dec., working interval pH 4.5–7.3, response time 60 s. The potentiometric coefficients of selectivity of the metamizole-selective electrode with respect to various ions have been determined. The possibility of determining metamizole in a medicinal product has been tested. The results of the analyses show good agreement between the two methods (relative error less than 7.0%) with coefficients of variation less than 5% for MT-SE and iodometric methods.

One of the sensitive and inexpensive methods used for the analysis of water bodies is the ionometry, the development of which is associated with the introduction of new ion-selective electrodes into the practice of potentiometric analysis. An optimized composition of the membrane for the manufacturing of a zinc-selective electrode based on polyvinyl chloride modified with 2-mercaptobenzthiazole (MPVC) is proposed with the following ratio of ingredients (in wt. %): Polyvinyl chloride - 31.7; dioctyl sebacate - 66.3; potassium tetra-p-chlorophenylborate - 0.5; MPVH - 1.5. The working range of pH was established with a minimum potential drift, which was 1.5 - 3. The slope of the electrode function was calculated as 30.1 ± 0.3 mV. According to the dependence of the electrode potential for the selected composition of the membrane on the logarithm of the zinc ion concentration, it was found that the proposed model of the electrode operates in the concentration range of 1∙10-5 - 1∙10-1 mol / L, with a detection limit of 0.65 mg / l. The stabilization time of the potential within 1 mV was 15 - 20 s. The potentiometric coefficients of the selectivity of the zinc selective electrode with respect to various ions have been determined. The conditions for the determination of zinc using the obtained sensor in alloys and wastewater were proposed. The electrode with the membrane based on polyvinyl chloride modified with 2-mercaptobenzthiazole can be used as an alternative to the industrial electrode XC-Zn-001 for the determination of zinc ions in various objects. The obtained experimental data was close in accuracy to the results obtained by the atomic absorption methods, as well as the ionometry using the industrial electrode. In conclusion, the electrode with the membrane based on polyvinyl chloride modified with 2-mercaptobenzthiazole can be used as an alternative to XC-Zn-001.

Четвертичные аммониевые соединения, и среди них, в частности, соли цетилпиридиния (ЦП) находят широкое применение в качестве антисептиков и дезинфицирующих средств, для местного лечения инфекционно-воспалительных процессов слизистой горла и полости рта, в составе таблеток для рассасывания, пастилок, гелей, средств гигиены полости рта. В работе предложены условия определения цетилпиридиния хлорида, обладающего противомикробным действием, в некоторых разрешенных к медицинскому применению ПАВ-содержащих фармацевтических препаратах методом твердофазной спектрофотометрии и тест-методом. В качестве твердофазной матрицы использована льняная ткань (ЛН). В работе показана эффективность сорбционного извлечения хлорида ЦП в виде его ионного ассоциата с бисазокрасителем сульфоназо (СФН). Анализ спектров поглощения твердофазных систем [ЛН∙СФН] и [ЛН∙СФН]-ЦП показывает, что реагент при рН≥4 практически не извлекается, а в присутствии ЦП сорбция наблюдается во всем исследуемом диапазоне рН с максимумом рН_max = 5. Для предложенного тест-метода диапазон определяемых концентраций ЦП составил 1.0-16 мг/дм³, предел обнаружения – 0.4 мг/дм³; для твердофазно-спектрофотометрического определения диапазон определяемых концентраций ЦП составил 0.5-24 мг/дм³, предел обнаружения – 0.2 мг/дм³. Продемонстрирована возможность определения ЦП в фармацевтических препаратах.   Ключевые слова: хлорид цетилпиридиния, определение, твердофазная спектрофотометрия, тест-метод, фармацевтические препараты, ионные ассоциаты, льняная ткань.