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Raman line mapping as a fast method for analyzing pharmaceutical bead formulations.

Authors
  • Sasić, Slobodan
  • Clark, Donald A
  • Mitchell, John C
  • Snowden, Martin J
Type
Published Article
Journal
The Analyst
Publication Date
Nov 01, 2005
Volume
130
Issue
11
Pages
1530–1536
Identifiers
PMID: 16222376
Source
Medline
License
Unknown

Abstract

This paper describes the use of principal component analysis (PCA) to de-noise Raman spectra and considerably shorten data acquisition time in Raman mapping experiments. A solid dosage pharmaceutical material (bead) is mapped by a Raman line-mapping system. The mapping acquisition time was varied from 30 s (usually employed in practice) to only 3 s. Apparently excessive noise in the maps measured for 3 s is removed by PCA and the maps of all three components of the bead are then binarized and compared. It is found that spatial difference is negligible despite the remarkably different acquisition times employed. The spectra acquired for 3 s and reconstructed via PCA are found to largely overlap with the spectra acquired for 30 s. The signal to noise ratio of the Raman mapping spectra does not obey the expected root t dependence, thereby preventing straightforward estimation of the shortest usable acquisition time (which is to a lesser extent also a function of the binarization threshold). The results reveal that Raman microscopy can be considered a fast method for mapping some materials, in contrast to the established opinion that it is an inherently slow technique.

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