The influence of particle size on the intensity and reproducibility of Raman spectra of compacted samples
Gómez Salazar, Diego Alonso (Universitat Autònoma de Barcelona. Departament de Química)
Coello Bonilla, Jordi (Universitat Autònoma de Barcelona. Departament de Química)
Maspoch Andrés, Santiago (Universitat Autònoma de Barcelona. Departament de Química)

Date:	2019
Abstract:	Given the growing interest in the application of Raman spectroscopy for quantitative purposes in solid pharmaceutical preparations, a revision of the effect of particle size on Raman spectra of compacted samples is presented. For this purpose, a set of tablets of potassium hydrogen phthalate (KHP) of different particle size were prepared. KHP was used because of its purity and stability, which allow to consider that samples will not be altered during measurements; but also because of its chemical structure (aromatic ring and carboxylic groups), that are present in many active pharmaceutical ingredients (API). The latter makes possible to consider KHP as a model pseudo-API. As KHP tablets only contain a pure compound, the mapping strategy that was considered for measuring our samples will not be affected by subsampling issues. The spectra variance can be attributed to the intrinsically reproducibility in recording the spectra (which mainly depends on the instrument set-up) and the site-to-site differences in elastic scattering properties. Two different instrumental optics have been studied: a macro-Raman system and a Raman microscope (500 μm and 50 μm laser spot size, respectively). The effect of the spectra preprocessing is also evaluated. The overall results demonstrate raw Raman intensity increases with particle size up to a value that depends on tablet width and that the applied spectral preprocessing (baseline correction and a unit vector normalization), reduces the differences in Raman intensities due to the particle size, but does not completely eliminate it for the lower particle sizes (< 20 μm). For tablets containing particles with predefined sizes, it corrects the mapping site-to-site differences in elastic scattering.
Grants:	Ministerio de Economía y Competitividad CTQ 2016-79696-P Agència de Gestió d'Ajuts Universitaris i de Recerca 2009/SGR-1470
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, i la comunicació pública de l'obra, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. No es permet la creació d'obres derivades.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Raman spectroscopy ; Particle size ; Peak intensity ; Reproducibility of a raman spectrum
Published in:	Vibrational Spectroscopy, Vol. 100 (January 2019) , p. 48-56, ISSN 0924-2031

DOI: 10.1016/j.vibspec.2018.10.011

9 p, 851.7 KB

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