UV spectra of aqueous or ethanolic solutions of twenty-seven active pharmaceutical ingredients

Introduction: UV spectrophotometry is the simplest method of quantitative analysis of active pharmaceutical ingredients. It is widely used in developing active pharmaceutical ingredients, quantifying impurities, dissolution testing, and quantifying nucleic acids and proteins inpharmaceutical development. However, there is no convenient library of UV spectra of pharmaceutical ingredients in pure distilled water, and it is sometimes hard to find the necessary information in the literature.Aim: This study aims to create a dataset of UV spectra of 27 common pharmaceutical ingredients in aqueous or (for those insoluble in water) ethanolic solutions and to review the analytical methods of determination of these ingredients based on these spectral data that were already developed.Materials and Methods: The aqueous (or ethanolic for those insoluble in water) solutions of 27 active pharmaceutical ingredients were prepared, and their UV spectra were recorded.Results and Conclusion: UV spectra of aqueous solutions of amlodipine besylate, articaine hydrochloride, bendazole hydrochloride, betaxolol hydrochloride, carbamazepine, citicoline sodium, chloropyramine, clopidogrel bisulfate, dexketoprofen trometamol, drotaverine hydrochloride, 2-ethyl-6-methyl-3-hydroxypyridine succinate, ketorolac trometamol, loperamide hydrochloride, menadione sodium bisulfite, metamizole sodium, metoclopramide hydrochloride, metoprolol tartrate, moxifloxacin hydrochloride, nicotinic acid (niacin), norepinephrine hydrochloride (noradrenaline hydrochloride), paracetamol (acetaminophen), and valacyclovir, and ethanolic solutions of carvedilol, haloperidol, indapamide, ketoprofen, and spironolactone are presented. The wavelengths of absorbance maxima for each compound are given. The methods of UV-spectrophotometric determination of these active pharmaceutical ingredients available in literature are reviewed

Core-shell and heterostructured silver-nickel nanocatalysts fabricated by gamma-radiation induced synthesis for oxygen reduction in alkaline media

To reach commercial viability for fuel cells, one needs to develop active and robust Pt-free electrocatalysts. Silver has great potential to replace Pt as the catalyst for the oxygen reduction reaction (ORR) in alkaline media due to its low cost and superior stability. However, its catalytic activity needs to be improved. One possible solution is to fabricate bimetallic nanostructures, which demonstrate a bifunctional enhancement in the electrochemical performance. Here, two types of bimetallic silver-nickel nanocatalysts, core-shells (Ag@NiO) and heterostructures (Ag/Ni), are fabricated using gamma-radiation induced synthesis. The Ag@NiO nanoparticles consist of an amorphous, NiO layer as a shell and a facetted crystalline Ag particle as a core. Meanwhile, the Ag/Ni heterostructures comprise Ag particles decorated with Ni/Ni(oxy-hydro)-oxide clusters. Both materials demonstrate similar and increased alkaline ORR activity as compared to monometallic catalysts. It was revealed that the enhanced catalytic activity of the core-shells is mainly attributed to the electronic ligand effect. While in the Ag/Ni heterostructures, a lattice mismatch between the Ni-based clusters and Ag implies a significant lattice strain, which, in turn, is responsible for the increased activity of the catalyst. Also, the Ag/Ni samples exhibit good stability under operating conditions due to the existence of stable Ni3+ compounds on the surface

Henry’s Law Constant of Noble Gases in Water, Methanol, Ethanol, and Isopropanol by Experiment and Molecular Simulation

Henry’s law constant data for the noble gases helium, neon, argon, krypton, xenon, and radon in the pure solvents water, methanol, ethanol, and propan-2-ol are predicted over a wide temperature range by molecular simulation. Furthermore, gas solubility measurements are carried out for neon, krypton, and xenon in propan-2-ol, yielding experimental Henry’s law constant values that are employed, together with data from the literature, to evaluate present simulation results. Suitable molecular force field models are identified for each binary system, and new models for helium and neon are presented. By examining the entire set of binary systems, a characteristic trend of the solubility behavior concerning the molecular size of the solutes and solvents is identified. The present work contributes consistent Henry’s law constant data for 24 binary solute–solvent pairs over the entire relevant temperature range and improves the database considerably

UV-Spectrophotometric Determination of the Active Pharmaceutical Ingredients Meloxicam and Nimesulide in Cleaning Validation Samples with Sodium Carbonate

The spectrophotometric methods of determination of the active pharmaceutical ingredients meloxicam and nimesulide were reviewed and a simple UV-spectrophotometric method for the determination of these active pharmaceutical ingredients in industrial equipment cleaning validation samples was proposed. The methods were based on extraction of the residual quantities of meloxicam and nimesulide from the manufacturing equipment surface by the concentrated sodium carbonate solution and the subsequent UV-spectrophotometric determination of the basic forms of the drugs at the wavelength of 362 nm for meloxicam and at 397 nm for nimesulide. The calibration graphs were linear in the range from 5 to 25 mg/L of both nimesulide and meloxicam, the molar attenuation coefficients were 6100 m2/mol for nimesulide and 9100 m2/mol for meloxicam, the limit of detection was 0.8 mg/L for nimesulide and 1.9 mg/L for meloxicam and the limit of quantification was 2.5 mg/L for nimesulide and 5.8 mg/L for meloxicam. The methods were selective with respect to the common excipients, showed a good accuracy (the relative uncertainty did not exceed 7%) and precision (the relative standard deviation did not exceed 4%), did not require lengthy sample preparation or sophisticated laboratory equipment and were suitable for the routine analysis of cleaning validation samples

Thermodynamics of Chemical and Electrochemical Stability of Fe – Ge System Alloys

The standard Gibbs energies of formation of intermatallides Fe6Ge5, FeGe, FeGe2 were estimated. Thermodynamic properties of α- and β- solid metallic solutions of Fe – Ge system and spinel solutions of Fe3O4 – Fe2GeO4 system were determined. The state diagram of Fe – Ge – O system and the potential – рН diagram of Fe – Ge – H2O system at 25ºС were plotted. The thermodynamic features of the corrosion-electrochemical behaviour of Fe – Ge system was discusse

Method of estimation of corrosion stability of multicomponent alloys using equilibrium and polarization potential - pH diagrams

Purpose - The purpose of this study is to develop a method of thermodynamic and kinetic evaluation of corrosion properties of alloys. Design/methodology/approach - Method of estimation of corrosion-electrochemical behaviour of multicomponent alloys is proposed. The method takes into account both thermodynamic and kinetic data and is based on mutual construction of equilibrium and polarization potential pH diagrams. The usage of the proposed method is illustrated in the example of the structural steel 20KT. Findings - Passivation of steel 20KT is determined by formation of oxide film based on magnetite (Fe3O4); silicon, manganese and copper oxides as well as manganese sulphides can be locally included into the inner side of the passivation layer. An experimental potential - pH diagram of steel 20KT is constructed. Interpreting the results of polarization measurements revealed good agreement between equilibrium and polarization potential - pH diagrams. Originality/value - It is shown in the example of structural steel 20KT that for interpretation of experimental potential - pH diagrams, one should compare them with corresponding equilibrium diagrams for multicomponent alloys rather than with Pourbaix diagrams for pure metals. The corrosion properties of steel 20KT are estimated using equilibrium and polarization potential - pH diagrams