The Chemistry & Biochemistry Colloquium Series presents Dr. Willem Windig on “Practical Application of Chemometrics” on Monday, Oct. 5, at 4:10 p.m. in Clippinger 194.
Windig is Chief Eigenspectroscopist with Eigenvector Research Inc.
Willem Windig
Abstract: This presentation will show several techniques that help the interpretation of data in a practical environment. The presentation has three parts. a) Data processing of electrospray Liquid Chromatographpy Mass Spectrometry (LCMS). The advantage of introducing liquid sample has the disadvantage of a significant contribution in the resulting Total Ion Chromatogram (TIC). Manual selection of ion chromatograms is very time consuming. The Component Detection Algorithm (CODA) is a simple algorithm that assigns a quality value to each of the mass chromatograms (1). Selection of only ion chromatograms with a high quality results in a high quality reduced TIC. As a next step, selecting the ion chromatograms that are different between highly similar sample, e.g., different batches of the same material, will be shown. b) Multivariate Curve Resolution (MCR) is a powerful technique to obtain estimates of the pure components of spectral mixture data. However, generally there is a range of solutions possible. A recent improvement of MCR enables to obtain solutions with maximum contrast between the resolved spectra, or maximum contrast between the resolved contributions (‘concentrations’) (2,3). An example will be shown of Secondary Ion Mass Spectrometry (SIMS) imaging of a mixture of two components and other examples. c) Independent Component Analysis (ICA) has currently a lot of interest in chemometrics. However, the requirement of independence is a limiting factor. A recently developed technique shows that for a certain class of samples simply adding sparsity to the data, in the form of adding zeros or use a wavelet transform, enables the resolution of data by ICA that could not be resolved before (4). The technique will be demonstrated with SIMS imaging data of a tablet, existing of the active material, excipient and a coating.
1) W. Windig, The use of the Durbin-Watson criterion for noise and background reduction of complex
Liquid Chromatography/Mass spectrometry data and a new algorithm to determine sample
differences. J. Chemom. Intell. Lab. Syst., 77, 2005, 106-214.
2) W. Windig, M.R. Keenan, Angle-Constrained Alternating Least Squares, Appl. Spectr. 65, 2011,
349-357.
3) W. Windig, J. M. Shaver, M. R. Keenan, B. M. Wise, Simplification of alternating least squares
solutions with contrast enhancement, Chemom. Intell. Lab. Syst., 117, 2012, 159-168
4) W. Windig, M.R. Keenan, Homeopathic ICA: A simple approach to expand the use of independent
component analysis (ICA), Chemom. Intell. Lab. Syst., 142, 2015, 54-63
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