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You searched for subject:(Erythromycin Thermal properties). One record found.

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Nelson Mandela Metropolitan University

1. Neglur, Rekha R. Physical properties of solid-state erythromycin derived compounds.

Degree: Faculty of Science, 2016, Nelson Mandela Metropolitan University

This thesis investigated the physical properties of the macrolide antibiotics: Erythromycin dihydrate (EM-DH), Roxithromycin monohydrate (RM-MH) and Azithromycin dihydrate (AZM-DH). The abovementioned hydrate compounds were investigated in terms of the hydrate-anhydrate crystal structure stability, dehydration and observed polymorphism under controlled temperature heating programs. Identified hydrate and anhydrate polymorphs were subjected to physical stability testing during controlled storage. EM-DH was characterized by thermal analysis (DSC, TGA), X-ray diffraction, FTIR and microscopy. Dehydration of EM-DH at temperatures of 100, 157 and 200°C (followed by supercooling to 25°C) produced the form (I) anhydrate (Tm =142.9°C), form (II) anhydrate (Tm = 184.7°C ) and amorph (II) (Tg = 118°C) respectively. The attempts to produce amorph (I) from melting (in vicinity of form (I) melt over temperature range 133°C to 144°C) and supercooling was unsuccessful due to the high crystallization tendency of the form (I) melt. Brief humidity exposure and controlled temperature (40°C)/ humidity storage for 4 days (0-96% RH) revealed hygroscopic behaviour for the anhydrate crystal (forms (I) and (II)) and amorph (II) forms. Form (II) converted to a nonstoichiometric hydrate where extent of water vapour absorption increased with increased storage humidity (2.1% absorbed moisture from recorded TGA at 96% RH). Amorph (II) exhibited similar trends but with greater water absorption of 4.7% (recorded with TGA) at 96% RH. The pulverization and sieving process of amorph (II) (at normal environmental conditions) was accompanied by some water vapour absorption (1.1%). A slightly lower absorbed moisture content of 3.3% (from TGA) after controlled 4 days storage at 40°C/ 96% RH was recorded. This suggested some physical instability (crystallization tendency) of amorph (II) after pulverization. The thermally induced dehydration of RM-MH by DSC-TG was evaluated structurally (SCXRD), morphologically (microscopy) and by kinetic analysis. Various kinetic analysis approaches were employed (advanced, approximation based integral and differential kinetic analysis methods) in order to obtain reliable dehydration kinetic parameters. The crystal structure was little affected by dehydration as most H-bonds were intramolecular and not integral to the crystal structure stability. Kinetic parameters from thermally stimulated dehydration indicated a multidimensional diffusion based mechanism, due to the escape of water from interlinked voids in crystal. The hygroscopicity of the forms RM-MH, Roxithromycin-anhydrate and amorph glass (Tg = 81.4°C) were investigated. Roxithromycinanhydrate (crystalline) converted readily to RM-MH which were found to be compositionally stable over the humidity range 43-96%RH. Amorphous glass exhibited increased water vapour absorption with increasing storage humidity (40°C/ 0-96% RH). TG analysis suggested a moisture content of 3.5% at 96% RH after 4 storage days. DSC and powder XRD analysis of stored pulverised amorphous glass…

Subjects/Keywords: Erythromycin  – Thermal properties; Azithromycin  – Thermal properties

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Neglur, R. R. (2016). Physical properties of solid-state erythromycin derived compounds. (Thesis). Nelson Mandela Metropolitan University. Retrieved from http://hdl.handle.net/10948/7228

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Neglur, Rekha R. “Physical properties of solid-state erythromycin derived compounds.” 2016. Thesis, Nelson Mandela Metropolitan University. Accessed September 23, 2019. http://hdl.handle.net/10948/7228.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Neglur, Rekha R. “Physical properties of solid-state erythromycin derived compounds.” 2016. Web. 23 Sep 2019.

Vancouver:

Neglur RR. Physical properties of solid-state erythromycin derived compounds. [Internet] [Thesis]. Nelson Mandela Metropolitan University; 2016. [cited 2019 Sep 23]. Available from: http://hdl.handle.net/10948/7228.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Neglur RR. Physical properties of solid-state erythromycin derived compounds. [Thesis]. Nelson Mandela Metropolitan University; 2016. Available from: http://hdl.handle.net/10948/7228

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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