title: Quantitative analysis of mannitol polymorphs. FT-Raman spectroscopy.
abstract: Mannitol is a polymorphic excipient which is usually used in pharmaceutical products as the beta form, although other polymorphs (alpha and delta) are common contaminants. Binary mixtures containing beta and delta mannitol were prepared to quantify the concentration of the beta form using FT-Raman spectroscopy. Spectral regions characteristic of each form were selected and peak intensity ratios of beta peaks to delta peaks were calculated. Using these ratios, a correlation curve was established which was then validated by analysing further samples of known composition. The results indicate that levels down to 2% beta could be quantified using this novel, non-destructive approach. Potential errors associated with quantitative studies using FT-Raman spectroscopy were also researched. The principal source of variability arose from inhomogeneities on mixing of the samples; a significant reduction of these errors was observed by reducing and controlling the particle size range. The results show that FT-Raman spectroscopy can be used to rapidly and accurately quantitate polymorphic mixtures.
authors.affiliation: Drug Delivery Group, School of Pharmacy, University of Bradford, West Yorkshire Bradford, UK.
authors.forename: Sarra N
authors.initials: SN
authors.lastname: Campbell Roberts
authors.forename: Adrian C
authors.initials: AC
authors.lastname: Williams
authors.forename: Ian M
authors.initials: IM
authors.lastname: Grimsey
authors.forename: Steven W
authors.initials: SW
authors.lastname: Booth
mesh_terms: D005079:Excipients / Q000032:analysis; D008353:Mannitol / Q000032:analysis*; D013059:Spectrum Analysis, Raman / Q000379:methods*; D014961:X-Ray Diffraction / Q000379:methods
chemical_list: D005079:Excipients; D008353:Mannitol