МЕТОДОЛОГИЧЕСКИЙ ПОДХОД К ПЛАНИРОВАНИЮ ЭКСПЕРИМЕНТА ПРИ ВЫБОРЕ КАЧЕСТВЕННЫХ РЕАКЦИЙ ДЛЯ ПОДТВЕРЖДЕНИЯ ПОДЛИННОСТИ КОМПОНЕНТОВ ЛЕКАРСТВЕННОГО СРЕДСТВА (НА ПРИМЕРЕ АСКОРБИНОВОЙ КИСЛОТЫ)

The need for identification  testing of active substances or excipients in multi-component medicinal products,  including the use of qualitative tests, calls for research substantiating the choice of tests and test conditions  with due regard to interference  effects caused by other components  of medicinal products and the amount of the sample used. The aim of the study was to develop a methodological approach to designing experiments while selecting qualitative reactions for identification testing of a medicinal product component based on the results of studies investigating the possibility of using known qualitative tests (as illustrated by ascorbic acid in a multi-component product — 0.4 mg of ascorbic acid per 100 mg of the vial contents)  with due regard to interference on the part of other medicinal product components and the amount of the sample used. Material and methods: the study focused on a multi-component medicinal product — lyophilisate for solution for intravenous and intramuscular  injections containing an antiinflammatory active substance and ascorbic acid as a stabilizing agent (antioxidant). The analysis of literature sources helped to determine qualitative tests that were assessed for potential use for identification testing of ascorbic acid as a component of the analysed medicinal product. The study involved experimental testing of the qualitative reactions based on acidic and reducing properties of ascorbic acid. Results: it was demonstrated that several well-known qualitative tests could be used for identification  testing of ascorbic acid as a component of the analysed medicinal product,  namely, the reaction of ferrous ascorbate formation  and the reaction of silver nitrate reduction to metallic silver after preliminary separation of ascorbic acid from the other medicinal product components, as well as the reaction of Prussian blue formation,  iodine test and reaction with a potassium permanganate solution, which do not require additional sample preparation.  It is not practicable to use the reaction with a methylene blue solution and the Fehling’s reagent reaction for this particular medicinal product,  since their results are feeble. Conclusions: the analysis of the multi-component medicinal product helped to develop a methodological  approach to choosing qualitative reactions for identification testing of one of the medicinal product’s components  (e.g., ascorbic acid). The suggested algorithm includes the choice of reactions, determination of their sensitivity and applicability for a particular medicinal product, analysis of the other components’ effects on the results of the chemical reaction,  and the need for additional sample preparation.  The whole complex of the studies performed helped to determine qualitative reactions and optimal conditions for identification testing of the analysed substance.Необходимость подтверждения подлинности  действующих  или  вспомогательных веществ  многокомпонентных лекарственных средств,  в том числе с использованием качественных  реакций, влечет за собой  необходимость  проведения исследований по выбору реакций  и условий их проведения с учетом мешающего  влияния других компонентов лекарственного средства  и количества  используемого образца.  Цель работы: разработка  методологического подхода к планированию эксперимента при выборе  качественных  реакций  для подтверждения подлинности определяемого компонента лекарственного средства на основании результатов исследований возможности использования известных качественных  реакций  (на примере  аскорбиновой кислоты  в многокомпонентном лекарственном средстве — 0,4 мг аскорбиновой кислоты / 100 мг содержимого  флакона) с учетом мешающего влияния других компонентов лекарственного средства и количества  используемого образца.  Материалы и методы: в качестве  объекта исследования было выбрано  многокомпонентное лекарственное средство  — лиофилизат для приготовления раствора  для внутривенного и внутримышечного введения  с лекарственным веществом,  обладающим  противовоспалительным действием,  в состав которого  входит аскорбиновая кислота  в качестве  стабилизатора (антиоксиданта). В результате анализа  данных литературы  выбраны  качественные реакции  для проведения исследований возможности их использования для подтверждения  подлинности аскорбиновой кислоты  в изучаемом  лекарственном средстве.  Проведена  экспериментальная проверка  реакций, основанных на кислотных  и восстановительных свойствах аскорбиновой кислоты.  Результаты: установлено, что в изучаемом многокомпонентном лекарственном средстве для подтверждения подлинности аскорбиновой кислоты могут быть применимы несколько известных качественных реакций: реакции образования аскорбината железа и восстановления нитрата серебра до металлического серебра после предварительного отделения аскорбиновой кислоты  от других компонентов лекарственного средства,  а также реакция  образования берлинской лазури,  йодная проба и реакция  с раствором  перманганата калия,  не требующие  дополнительной пробоподготовки. Использование реакций  с раствором  метиленового  синего и реактивом  Фелинга  применительно к данному лекарственному средству нецелесообразно, так как результат указанных реакций  слабо выражен. Выводы: на примере многокомпонентного лекарственного средства разработан  методологический подход к выбору качественных  реакций  для подтверждения подлинности одного  из компонентов лекарственного средства  (например, аскорбиновой кислоты).  Алгоритм действий включает в себя выбор реакций, определение их чувствительности и целесообразности применения для конкретного лекарственного средства,  изучение  влияния других его компонентов на результат химической реакции, а также необходимость  или отсутствие дополнительной пробоподготовки. Совокупность проведенных  исследований позволяет сделать выбор качественных  реакций  и оптимальных  условий  их проведения для достижения поставленной цели — подтверждения подлинности определяемого вещества

A METHODOLOGICAL APPROACH TO DESIGNING EXPERIMENTS WHEN DEALING WITH IDENTIFICATION TESTS FOR MEDICINAL PRODUCT COMPONENTS (AS ILLUSTRATED BY ASCORBIC ACID)

The need for identification  testing of active substances or excipients in multi-component medicinal products,  including the use of qualitative tests, calls for research substantiating the choice of tests and test conditions  with due regard to interference  effects caused by other components  of medicinal products and the amount of the sample used. The aim of the study was to develop a methodological approach to designing experiments while selecting qualitative reactions for identification testing of a medicinal product component based on the results of studies investigating the possibility of using known qualitative tests (as illustrated by ascorbic acid in a multi-component product — 0.4 mg of ascorbic acid per 100 mg of the vial contents)  with due regard to interference on the part of other medicinal product components and the amount of the sample used. Material and methods: the study focused on a multi-component medicinal product — lyophilisate for solution for intravenous and intramuscular  injections containing an antiinflammatory active substance and ascorbic acid as a stabilizing agent (antioxidant). The analysis of literature sources helped to determine qualitative tests that were assessed for potential use for identification testing of ascorbic acid as a component of the analysed medicinal product. The study involved experimental testing of the qualitative reactions based on acidic and reducing properties of ascorbic acid. Results: it was demonstrated that several well-known qualitative tests could be used for identification  testing of ascorbic acid as a component of the analysed medicinal product,  namely, the reaction of ferrous ascorbate formation  and the reaction of silver nitrate reduction to metallic silver after preliminary separation of ascorbic acid from the other medicinal product components, as well as the reaction of Prussian blue formation,  iodine test and reaction with a potassium permanganate solution, which do not require additional sample preparation.  It is not practicable to use the reaction with a methylene blue solution and the Fehling’s reagent reaction for this particular medicinal product,  since their results are feeble. Conclusions: the analysis of the multi-component medicinal product helped to develop a methodological  approach to choosing qualitative reactions for identification testing of one of the medicinal product’s components  (e.g., ascorbic acid). The suggested algorithm includes the choice of reactions, determination of their sensitivity and applicability for a particular medicinal product, analysis of the other components’ effects on the results of the chemical reaction,  and the need for additional sample preparation.  The whole complex of the studies performed helped to determine qualitative reactions and optimal conditions for identification testing of the analysed substance

Low-temperature catalytic decomposition of hydrogen sulfide on metal catalysts under layer of solvent

<p>When hydrogen sulfide decomposition {2 H₂S ↔ 2 H₂ + S₂^(gas)} is carried out in the flow regime at room temperature on metal catalysts placed in a liquid capable of dissolving H₂S and sulfur, the reaction equilibrium can be significantly (up to 100%) shifted to the right yielding the desired product – hydrogen. The process efficiency was demonstrated using aqueous solutions of monoethanolamine (MEA), sodium carbonate, which is widely used in industry for H₂S absorption from tail gases, and aqueous hydrazine as examples. IR and Raman spectroscopy data demonstrated that sulfur obtained in the solutions is in the form of diatomic molecules. DFT calculations showed that diatomic sulfur forms weakly bound coordinative complexes with solvent molecules. Some problems related to sulfur accumulation and recovery from the solvents are discussed.</p