A review of information theory in analytical chemometrics

Eckschlager, K.; Štěpánek, Vladimír; Danzer, Klaus

doi:10.1002/cem.1180040303

Cited by 31 publications

(15 citation statements)

References 53 publications

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“…[25,27] In the case of investigating chemical reactions via in situ Raman spectroscopy, the problem is to understand the nature of a chemical reaction Figure 1. Overlay of measured in situ Raman spectra for acetic anhydride alcoholysis with methanol.…”

Section: Measuring Samplementioning

confidence: 99%

Information‐theoretic chemometric analyses of Raman data for chemical reaction studies

Chew

2011

J Raman Spectroscopy

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A methodology of multivariate chemometric techniques based on the information-theoretic approach was applied for elucidating chemical reaction information from a Raman data array R m×ν that arises from in situ reaction monitoring. This reaction-induced dynamic dataset R m×ν can be contaminated by random cosmic ray spikes found in the midst of characteristic spectral variations associated with the disappearance or emergence of Raman active reactants, intermediates and products. Such spurious cosmic spikes were identified and removed using a novel and fast numerical approach based on maximum and minimum spectral entropy principles while preserving the genuine reaction-induced spectral variations. Subsequently, the band-target entropy minimization (BTEM) algorithm, a minimum spectral entropy based self-modeling curve resolution technique, was applied to recover the pure component spectra of Raman active chemical species. Information gain through the chemometric analyses was calculated using information entropies with base 2 logarithm. This sequence of information-theoretic chemometric analyses (or transinformations) was successfully tested on the reaction spectral data obtained from alcoholysis of acetic anhydride, which contains four Raman active chemical species. It is envisioned that this series of multivariate statistical analyses will be useful in chemical reaction studies and process analytical technology (PAT) applications that utilize in situ Raman spectroscopy to monitor transient dynamic changes in chemical concentrations, and also in Raman microscopy/imaging data containing spatial variations.

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Section: Measuring Samplementioning

confidence: 99%

Information‐theoretic chemometric analyses of Raman data for chemical reaction studies

Chew

2011

J Raman Spectroscopy

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“…The fragment ions related to the amino acids in the proteins [17][18][19] used in the PCA analysis of the TOF-SIMS data are shown in Table I. Since this protein A molecule does not contain cysteine (C) or tryptophan (W), fragment ions reported to be related to these residues, CHS + (m/z 45) from C, and The values of mutual information [20][21][22][23] were calculated comparing the protein A-immobilized sample at pH 7 (SpA at pH 7) with the reference samples, the protein Aimmobilized samples at pH 3 or 5 (SpA at pH 3 or 5), and those at pH 7 after being soaked in acid solutions (SpA at pH 7 after pH 3 or 5), respectively. Peaks of secondary ions at m/z = 40 to 500 were used for the calculation.…”

Section: Spectrum Analysismentioning

confidence: 99%

Evaluation of pH-Dependent Staphylococcal Protein A Structural Change Using TOF-SIMS

Aoyagi

Higuchi

Kato

et al. 2009

e-J. Surf. Sci. Nanotechnol.

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The evaluation of protein structural change is crucial for the study of protein-protein interactions and protein conformational changes. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) was used to detect pH dependent structural change in staphylococcal protein A (SpA), which is well known to the bind Fc region of immunoglobulins. TOF-SIMS spectra of SpA-immobilized samples in a pH 7 solution, in an acidic solution, and in a pH 7 solution after having been soaked in an acidic solution, respectively, were compared to select fragment ions specific to normal SpA at pH 7 using spectral analysis techniques such as principal component analysis (PCA) and the mutual information method. A fragment ion depending on change in the B and E domains of SpA were detected with this method. These findings demonstrate that structural change of SpA depending on pH change can be evaluated with TOF-SIMS together with spectrum analysis methods for the multivariate data.

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“…The term n(a i |b j ) is the number of spectra belonging to sample category i out of the spectra containing peaks greater than V. The best value of V is chosen to provide the largest I(A; B). [7,8] When I(A; B) = S(A), the peak intensity of each spectra is classifiable to the correct category.…”

Section: Tof-sims Spectra Analysis With Mutual Informationmentioning

confidence: 99%

Review of TOF‐SIMS bioanalysis using mutual information

Aoyagi

2008

Surface & Interface Analysis

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The evaluation of proteins on biodevices, such as the distribution or orientation of immobilized proteins, is one of the most important issues for the development of sophisticated biodevices. In this review, a description is provided of the application of one of the most sensitive surface analysis methods, time-of-flight secondary ion mass spectrometry (TOF-SIMS), to protein evaluation and TOF-SIMS spectra analysis using mutual information. TOF-SIMS is useful for the evaluation of biodevice surfaces, because TOF-SIMS provides submicron-scale chemical mapping and information on the chemical structures of the upper surface part of a protein. In addition, TOF-SIMS requires no pretreatment of samples, such as labeling with a fluorescent probe or coating with metallic thin films. Data analysis methods are, however, required to interpret the protein sample TOF-SIMS data, because the fragment ions from proteins are so complicated that it is difficult to predict them. In order to identify hidden important peaks related to protein samples out of the hundreds of peaks in TOF-SIMS spectra, mutual information has been used. Protein distribution on biodevices and the orientation of an immobilized protein obtained with this method are described in this review.

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A review of information theory in analytical chemometrics

Cited by 31 publications

References 53 publications

Information‐theoretic chemometric analyses of Raman data for chemical reaction studies

Information‐theoretic chemometric analyses of Raman data for chemical reaction studies

Evaluation of pH-Dependent Staphylococcal Protein A Structural Change Using TOF-SIMS

Review of TOF‐SIMS bioanalysis using mutual information

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