| 1. |
- Ali, Hassan, et al.
(författare)
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Computational and vibrational spectroscopic studies of ipratropium bromide
- 2009
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Ingår i: Drug Testing and Analysis. - : Wiley. - 1942-7603 .- 1942-7611. ; 1:2, s. 73-80
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Tidskriftsartikel (refereegranskat)abstract
- In this study, ipratropium bromide is investigated using vibrational spectroscopy and quantum chemical calculations. The structure of ipratropium bromide was optimised using density functional theory calculations and the geometry optimisation has been carried out on two conformations with and without intramolecular hydrogen bonding. Infrared and Raman spectra were calculated from the optimised structures. Manymodes in the calculated spectra could bematched with the experimental spectra and a description of the modes is given. By analysis of the theoretical vibrational modes, it is shown that ipratropium bromide specimens are likely to beamixture of the two conformations with and without intramolecular hydrogen bonding. In addition, several spectral features and band intensities in the CH and OH stretching regions are explained. Quantum mechanical calculations allowed improved understanding of ipratropium bromide and its vibrational spectra
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| 2. |
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| 3. |
- Ali, Hassan, et al.
(författare)
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Vibrational spectroscopic characterisation of salmeterol xinafoate polymorphs and a preliminary investigation of their transformation using simultaneous in situ portable Raman spectroscopy and differential scanning calorimetry
- 2008
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Ingår i: Analytica Chimica Acta. - : Elsevier BV. - 0003-2670 .- 1873-4324. ; 620:1-2, s. 103-12
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge and control of the polymorphic phases of chemical compounds are important aspects of drug development in the pharmaceutical industry. Salmeterol xinafoate, a long acting beta-adrenergic receptor agonist, exists in two polymorphic Forms, I and II. Raman and near infrared spectra were obtained of these polymorphs at selected wavelengths in the range of 488-1064 nm; significant differences in the Raman and near-infrared spectra were apparent and key spectral marker bands have been identified for the vibrational spectroscopic characterisation of the individual polymorphs which were also characterised with X ray diffractometry. The solid-state transition of salmeterol xinafoate polymorphs was studied using simultaneous in situ portable Raman spectroscopy and differential scanning calorimetry isothermally between transitions. This method assisted in the unambiguous characterisation of the two polymorphic forms by providing a simultaneous probe of both the thermal and vibrational data. The study demonstrates the value of a rapid in situ analysis of a drug polymorph which can be of potential value for at-line in-process control
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| 4. |
- Ali, Hassan, et al.
(författare)
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Vibrational spectroscopic study of budesonide
- 2007
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Ingår i: Journal of Raman Spectroscopy. - : Wiley. - 0377-0486 .- 1097-4555. ; 38:7, s. 903-908
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Tidskriftsartikel (refereegranskat)abstract
- The Raman spectrum of budesonide is reported for the first time, and molecular assignments are proposed on the basis of ab initio BLYP DFT calculations with a 6-31 G* basis set and vibrational wavenumbers predicted on a quasi-harmonic approximation. Comparison with previously published infrared data has explained several spectral features, and the relative band intensities in the C=O and C=C stretching regions are interpreted. The results from this study provide data that can be used for the preparative process monitoring of budesonide, an important steroidal pharmaceutical in various dosage forms, and its interaction with excipients and other components
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| 5. |
- Ali, Hassan, et al.
(författare)
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Vibrational spectroscopic study of fluticasone propionate
- 2009
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Ingår i: Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy. - : Elsevier BV. - 1386-1425 .- 1873-3557. ; 72:2, s. 244-247
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Tidskriftsartikel (refereegranskat)abstract
- Fluticasone propionate is a synthetic glucocorticoid with potent anti-inflammatory activity that has been used effectively in the treatment of chronic asthma. The present work reports a vibrational spectroscopic study of fluticasone propionate and gives proposed molecular assignments on the basis of ab initio calculations using BLYP density functional theory with a 6-31G* basis set and vibrational frequencies predicted within the quasi-harmonic approximation. Several spectral features and band intensities are explained. This study generated a library of information that can be employed to aid the process monitoring of fluticasone propionate.
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| 6. |
- Ali, Hassan, et al.
(författare)
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Vibrational spectroscopic study of salbutamol hemisulphate
- 2009
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Ingår i: Drug Testing and Analysis. - : Wiley. - 1942-7603 .- 1942-7611. ; 1:1, s. 51-56
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Tidskriftsartikel (refereegranskat)abstract
- Salbutamol hemisulphate is a relatively selective β 2-adrenergic agonist and is used as a bronchodilator. In this work, we present a detailed vibrational spectroscopic investigation of salbutamol hemisulphate using mid-infrared and near-infrared Fourier-transform (NIR-FT) Raman spectroscopies. These data are supported by quantum chemical calculations, which allow us to characterise the vibrational spectra of this compound reasonably. As such, this study could be viable for examining the way in which this drug interacts with its targetmolecules.
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| 7. |
- Ali, Hassan, et al.
(författare)
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Vibrational spectroscopic study of terbutaline hemisulphate
- 2009
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Ingår i: Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy. - : Elsevier BV. - 1386-1425 .- 1873-3557. ; 72:4, s. 715-719
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Tidskriftsartikel (refereegranskat)abstract
- The Raman spectrum of terbutaline hemisulphate is reported for the first time, and molecular assignments are proposed on the basis of ab initio BLYP DFT calculations with a 6-31G* basis set and vibrational frequencies predicted within the quasi-harmonic approximation; these predictions compare favourably with the observed vibrational spectra. Comparison with previously published infrared data explains several spectral features. The results from this study provide data that can be used for the preparative process monitoring of terbutaline hemisulphate, an important β2 agonist drug in various dosage forms and its interaction with excipients and other components
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| 8. |
- Ali, Hassan, et al.
(författare)
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Insight into thermally induced solid-state polymorphic transformation of sulfathiazole using simultaneous in situ Raman spectroscopy and differential scanning calorimetry
- 2009
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Ingår i: Journal of Raman Spectroscopy. - : Wiley. - 0377-0486 .- 1097-4555. ; 40:8, s. 887-892
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Tidskriftsartikel (refereegranskat)abstract
- Pharmaceutical solids exposed to thermal stress during manufacturing processes undergo various phase transformations in bulk drug substances or excipients, resulting in altered dosage form performance. Due to its relatively rapid spectral acquisition rate, as well as the possibility of incorporation into in-line monitoring, Raman spectroscopy is ideally suited to monitoring the transformation between different solid-state forms. In this study, we demonstrate that the transition temperature for polymorphs can be estimated from the transformation profiles obtained from real-time, in situ, simultaneous Raman spectroscopic, and differential scanning calorimetric data. Using this method, we have estimated the transition temperature of the solid-state transformation of the enantiotropically related sulfathiazole polymorphs III and I. These results suggest that this method is a useful approach to determine transition temperatures in systems that are not amenable to accessing other methods
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| 9. |
- Ali, Hassan, et al.
(författare)
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Noninvasive in situ identification and band assignments of some pharmaceutical excipients inside USP vials with FT-near-infrared spectroscopy
- 2009
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Ingår i: Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy. - : Elsevier BV. - 1386-1425 .- 1873-3557. ; 72:4, s. 890-896
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Tidskriftsartikel (refereegranskat)abstract
- For the manufacture of dosage forms all ingredients must be reliably identified. In this paper, the suitability of FT-NIR spectroscopy to identify potassium sorbate, sodium starch glycollate, calcium ascorbate, calcium carbonate, candelilla wax, maltosextrin, monohydrated and anhydrous lactose inside USP vials was investigated. Differentiation between the anhydrous and monohydrated forms of lactose was found to be possible by studying the regions of the near-infrared spectrum corresponding to the combination and first overtone stretching frequencies of water. The results show unequivocally the potential of FT-NIR spectroscopy for rapid, in situ and non-destructive identification of pharmaceutical excipients
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| 10. |
- Edwards, Howell G.M., et al.
(författare)
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Raman spectroscopy of natron : Shedding light on ancient Egyptian mummification
- 2007
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Ingår i: Analytical and Bioanalytical Chemistry. - : Springer Science and Business Media LLC. - 1618-2642 .- 1618-2650. ; 388:3, s. 683-689
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Tidskriftsartikel (refereegranskat)abstract
- The mummification ritual in ancient Egypt involved the evisceration of the corpse and its desiccation using natron, a naturally occurring evaporitic mineral deposit from the Wadi Natrun, Egypt. The deposit typically contains sodium carbonate, sodium bicarbonate and impurities of chloride and sulfate as its major elemental components. It is believed that the function of the natron was to rapidly remove the water from the cadaver to prevent microbial attack associated with subsequent biological tissue degradation and putrefaction. Several specimens of natron that were recently collected from the Wadi Natrun contained coloured zones interspersed with the mineral matrix that are superficially reminiscent of extremophilic cyanobacterial colonisation found elsewhere in hot and cold deserts. Raman spectroscopy of these specimens using visible and near-infrared laser excitation has revealed not only the mineral composition of the natron, but also evidence for the presence of cyanobacterial colonies in several coloured zones observed in the mineral matrix. Key Raman biosignatures of carotenoids, scytonemin and chlorophyll have been identified
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