Outer-product analysis (OPA) using PICA to study the influence of temperature on NIR spectra of water

• Type: Article in International Scientific Journal
• Date: 2005

Authors

Jaillais, B (Author) Other; Pinto, R (Author) Other; Barros, AS (Author) Other; Rutledge, DN (Author) Other

Journal

Title: Vibrational Spectroscopy

Vol. 39

Pages: 50-58

ISSN: 0924-2031

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 37 Citations

Scopus - 43 Citations

Other information

Authenticus ID: P-000-1CF

DOI: 10.1016/j.vibspec.2004.10.008

Abstract (EN): Outer-product analysis (OPA) is a method which makes it possible to emphasise co-evolutions of spectral regions in signals acquired in two different domains or even for the same domain. The calculation of the outer-product (OP) matrix linking the two domains corresponds to a mutual weighting of the two signals. Various statistical techniques-both univariate and multivariate-can be applied to these matrices to bring out these simultaneous variations. Applying principal components analysis (PCA) to the OP matrix allows to visualise both the distribution of the individuals (scores plots) and the simultaneous variations in the signals related to this distribution of the individuals (loadings). In the case of complex data sets with many sources of variation in the samples, partial least squares regression (PLS) can be used to direct the analysis in order to visualise those simultaneous variations that are associated with a particular evolution of the samples. In this study, we applied OPA to a data set concerning the evolution of near infrared (NIR) spectra of water as a function of temperature. The different loadings profiles obtained by PCA are compared with the synchronous and asynchronous variable-variable spectra obtained using 2D-correlation spectroscopy (2DCOS), in order to study the resemblances and the differences between the two techniques. The outer-product may also be calculated for the transposed matrices. In this case, the PCA loadings may be compared with the synchronous and asynchronous sample-sample spectra obtained by 2DCOS.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 9