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Vibrational overtone combination spectroscopy (VOCSY)—a new way of using IR and NIR data
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
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2007 (Engelska)Ingår i: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 388, nr 1, s. 179-188Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

This work explores a novel method for rearranging 1st order (one-way) infra-red (IR) and/or near infra-red (NIR) ordinary spectra into a representation suitable for multi-way modelling and analysis. The method is based on the fact that the fundamental IR absorption and the first, second, and consecutive overtones of NIR absorptions represent identical chemical information. It is therefore possible to rearrange these overtone regions of the vectors comprising an IR and NIR spectrum into a matrix where the fundamental, 1st, 2nd, and consecutive overtones of the spectrum are arranged as either rows or columns in a matrix, resulting in a true three-way tensor of data for several samples. This tensorization facilitates explorative analysis and modelling with multi-way methods, for example parallel factor analysis (PARAFAC), N-way partial least squares (N-PLS), and Tucker models. The vibrational overtone combination spectroscopy (VOCSY) arrangement is shown to benefit from the “order advantage”, producing more robust, stable, and interpretable models than, for example, the traditional PLS modelling method. The proposed method also opens the field of NIR for true peak decomposition—a feature unique to the method because the latent factors acquired using PARAFAC can represent pure spectral components whereas latent factors in principal component analysis (PCA) and PLS usually do not.

Ort, förlag, år, upplaga, sidor
2007. Vol. 388, nr 1, s. 179-188
Nyckelord [en]
Near-infrared, Infrared, Calibration, PARAFAC, Multi-way, Second-order advantage
Nationell ämneskategori
Analytisk kemi
Forskningsämne
analytisk kemi
Identifikatorer
URN: urn:nbn:se:su:diva-10782DOI: 10.1007/s00216-007-1180-8ISI: 000245292200022OAI: oai:DiVA.org:su-10782DiVA, id: diva2:177301
Tillgänglig från: 2008-01-07 Skapad: 2008-01-07 Senast uppdaterad: 2017-12-13Bibliografiskt granskad
Ingår i avhandling
1. Solving the correspondence problem in analytical chemistry: Automated methods for alignment and quantification of multiple signals
Öppna denna publikation i ny flik eller fönster >>Solving the correspondence problem in analytical chemistry: Automated methods for alignment and quantification of multiple signals
2012 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

When applying statistical data analysis techniques to analytical chemical data, all variables must have correspondence over the samples dimension in order for the analysis to generate meaningful results. Peak shifts in NMR and chromatography destroys that correspondence and creates data matrices that have to be aligned before analysis. In this thesis, new methods are introduced that allow for automated transformation from unaligned raw data to aligned data matrices where each column corresponds to a unique signal. These methods are based around linear multivariate models for the peak shifts and Hough transform for establishing the parameters of these linear models. Methods for quantification under difficult conditions, such as crowded spectral regions, noisy data and unknown peak identities are also introduced. These methods include automated peak selection and a robust method for background subtraction. This thesis focuses on the processing of the data; the experimental work is secondary and is not discussed in great detail.

All the developed methods are put together in a full procedure that takes us from raw data to a table of concentrations in a matter of minutes.

The procedure is applied to 1H-NMR data from biological samples, which is one of the toughest alignment tasks available in the field of analytical chemistry. It is shown that the procedure performs consistently on the same level as much more labor intensive manual techniques such as Chenomx NMRSuite spectral profiling.

Several kinds of datasets are evaluated using the procedure. Most of the data is from the field of Metabolomics, where the goal is to establish concentrations of as many small molecules as possible in biological samples.

Ort, förlag, år, upplaga, sidor
Stockholm: Department of Analytical Chemistry, Stockholm University, 2012. s. 74
Nationell ämneskategori
Kemi
Forskningsämne
analytisk kemi
Identifikatorer
urn:nbn:se:su:diva-74556 (URN)978-91-7447-485-5 (ISBN)
Disputation
2012-05-25, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 13:00 (Engelska)
Opponent
Handledare
Tillgänglig från: 2012-05-03 Skapad: 2012-03-16 Senast uppdaterad: 2012-05-02Bibliografiskt granskad

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Av författaren/redaktören
Alm, ErikKarlberg, BoTorgrip, Ralf J. O.
Av organisationen
Institutionen för analytisk kemi
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Analytical and Bioanalytical Chemistry
Analytisk kemi

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