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Semi-preparative isolation and characterization of a principal oxidative degradation product in galantamine hydrobromide by LC-ESI-MSn and 2D-NMR

100%

Thomas S. , Paul S. K. , Agarwal A. , Mathela C. S.

Acta Chromatographica

2014

tom Vol. 26, no. 3

429--438

Galantamine hydrobromide was subjected to oxidative stress degradation using hydrogen peroxide and analyzed as per the chromatographic conditions described in European Pharmacopoeia. The drug showed considerable degradation at ambient temperature resulting in the formation of two degradation products at relative retention times (RRTs) 0.63 and 2.52. The minor degradant at RRT 0.63 was identified as galantamine N-oxide. The principal degradant formed at RRT 2.52 was found to be unknown and has not been reported previously. The unknown impurity was identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) followed by isolation using semi-preparative high-performance liquid chromatography (HPLC). The isolated impurity was characterized using one-dimensional, two-dimensional nuclear magnetic resonance spectroscopy (1D and 2D NMR) and elemental analysis (EA). The principal degradant was found to be formed due to the generation of bromine and subsequent attack on the aromatic ring via in situ reaction between hydrogen bromide and hydrogen peroxide. The unknown impurity was characterized as (4aS,6R,8aS)-5,6,9,10,11,12-hexahydro-1-bromo-3-methoxy-11-methyl-4aH-[1]benzofuro [3a,3,2-ef] [2] benzazepin-6-ol.

Evaluation of the strength properties of materials intended for tracheobronchial tubes

100%

Sobota R. , Markowski J. , Joszko K. , Gzik-Zroska B. , Kawlewska E. , Gzik M.

Engineering of Biomaterials

2020

tom Vol. 23, no. 156

10--16

The desire to increase the comfort of patients and to continue production despite the decreasing amount of available materials on the market has led to the constant search for novel materials that could be used to obtain tracheobronchial tubes. The aim of this study is to determine the mechanical properties of a new thermoplastic elastomer. Two materials - the thermoplastic elastomer and the natural rubber were subjected to three tests: static tensile test, static compression test and static three-point bending test. During the static tensile test, samples of the tested materials were examined, and during the next two examinations, the final products. The materials underwent the processes of sterilization, hydrolytic degradation and degradation by oxidation. The treated samples were also tested in order to compare the obtained results. The mechanical properties of the tested materials improved both after the hydrolytic degradation and oxidative degradation, as well as after the sterilization process. Yet the thermoplastic elastomer revealed a more noticeable increase. The elastomer hardening is a positive phenomenon potentially leading to fewer accidental closures of the tubes cross-section. Both the sterilization process and various degradation methods improved the mechanical properties by strengthening the tested materials. This phenomenon seems to be desirable to avoid the closure of the implemented tube during its application.

Degradation of p-aminophenol by Fenton’s process. Influence of operational parameters

63%

Ghosh P. , Ghime D. , Lunia D.

tom Vol. 43, nr 3

255--267

Oxidative degradation of a model environmental pollutant, p-Aminophenol (PAP), in aqueous solution has been investigated in an environmentally friendly advanced oxidation Fenton process. Effects of various operating parameters such as pH of solutions, dosage of hydrogen peroxide and ferrous ions, initial PAP concentration and temperature on the degradation of PAP have been studied using a batch stirred ceil. Degradation kinetics for this pollutant was also investigated to determine the apparent rate constants (min-1)- The optimum conditions for the degradation of PAP solution (200-500 mg/dm3) were found to be pH = 3.0, 2400 mg H2O2dm, 300 mg Fe2+/dm3, 30°C. Under the optimum conditions, the degradation efficiency of PAP was 75% after 50 min of reaction. It was observed that process parameters play a major role in the overall degradation process.