Window factor analysis: Theoretical derivation and application to flow injection analysis data

Malinowski, Edmund R.

doi:10.1002/cem.1180060104

Cited by 271 publications

(102 citation statements)

References 12 publications

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“…The advantage of EWFA is that the concentration of one of the species can be calculated without knowledge of the concentration of the other species. 7, 21 As a result, it was not necessary to calculate all the concentrations in order to solve this problem. As was done for acetonitrile, the background was subtracted from all spectra.…”

Section: Spectroelectrochemistry In Bmimpf6mentioning

confidence: 99%

Electrochemistry and Spectroelectrochemistry of 1,4-Dinitrobenzene in Acetonitrile and Room-Temperature Ionic Liquids: Ion-Pairing Effects in Mixed Solvents

Atifi

2014

Anal. Chem.

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Room-temperature ionic liquids (RTILs) have been shown to have a significant effect on the redox potentials of compounds such as 1,4-dinitrobenzene (DNB), which can be reduced in two one-electron steps. The most noticeable effect is that the two one-electron waves in acetonitrile collapsed to a single two-electron wave in a RTIL such as butylmethyl imidazolium-BF4 (BMImBF4). In order to probe this effect over a wider range of mixed-molecular-solvent/RTIL solutions, the reduction process was studied using UV–vis spectroelectrochemistry. With the use of spectroelectrochemistry, it was possible to calculate readily the difference in E°’s between the first and second electron transfer (ΔE 12° = E 1° – E 2°) even when the two one-electron waves collapsed into a single two-electron wave. The spectra of the radical anion and dianion in BMImPF6 were obtained using evolving factor analysis (EFA). Using these spectra, the concentrations of DNB, DNB–•, and DNB2– were calculated, and from these concentrations, the ΔE 12° values were calculated. Significant differences were observed when the bis(trifluoromethylsulfonyl)imide (NTf2) anion replaced the PF6 – anion, leading to an irreversible reduction of DNB in BMImNTf2. The results were consistent with the protonation of DNB2–, most likely by an ion pair between DNB2– and BMIm+, which has been proposed by Minami and Fry. The differences in reactivity between the PF6 – and NTf2 – ionic liquids were interpreted in terms of the tight versus loose ion pairing in RTILs. The results indicated that nanostructural domains of RTILs were present in a mixed-solvent system.

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Section: Spectroelectrochemistry In Bmimpf6mentioning

confidence: 99%

Electrochemistry and Spectroelectrochemistry of 1,4-Dinitrobenzene in Acetonitrile and Room-Temperature Ionic Liquids: Ion-Pairing Effects in Mixed Solvents

Atifi

2014

Anal. Chem.

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“…Before WFA is introduced, the basic ideas of time warping techniques are [29] briefly described in the next section to the extent relevant to WFA.…”

Section: Shape Variation Of Sequential Factorsmentioning

confidence: 99%

Warped factor analysis

Hong

2009

Journal of Chemometrics

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Shifted factor analysis (SFA) is designed to fit overall position shifts of sequential factors as well as the variation of factor weights. SFA is one kind of nonlinear generalization of linear factor models such as the two-mode principal component model and the three-mode Parafac model. Warped factor analysis (WFA), presented here, further generalizes SFA so that it fits factor variation due to not only the position shifts and the systematic weighting but also more flexible shape changes of sequential factors. A quasi alternating least squares (ALS) procedure is developed for WFA, using a simplified warping of segmented sequential factors. The most unique property of WFA is that it allows sequential factors to change shape distinctively, which is unlike what is implicitly assumed in mapping of data profiles, namely that sequential factors change shape together. Unlike the two-mode factor/component models, two-mode SFA was empirically shown to yield an essentially unique solution, using the additional sources of information provided by fitting systematic position shifts. Likewise, factors recovered by two-mode WFA are likely to be essentially unique due to the systematic shape variance fit by the model, provided that the data contain sufficient sources of shape variation.

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“…With the help of SFA, six common components were extracted from the two peak clusters, assigned B1-B6 in the sample from extraction method 1 and b1-b6 in the sample from extraction method II (Fig. 10 (medium part) and (bottom part), respectively [Li, 2003;Liang, , 1994Karjalainen, 1992;Maeder, 1987;Malinowski ,1992;Malinowski, 1991;Windig, 1997;Gemperline, 1984]. …”

Section: On-line Comparison By Chemometric Methodsmentioning

confidence: 99%

Analytical Evaluation of Herbal Drugs

Kamboj¹

2012

Drug Discovery Research in Pharmacognosy

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Window factor analysis: Theoretical derivation and application to flow injection analysis data

Cited by 271 publications

References 12 publications

Electrochemistry and Spectroelectrochemistry of 1,4-Dinitrobenzene in Acetonitrile and Room-Temperature Ionic Liquids: Ion-Pairing Effects in Mixed Solvents

Electrochemistry and Spectroelectrochemistry of 1,4-Dinitrobenzene in Acetonitrile and Room-Temperature Ionic Liquids: Ion-Pairing Effects in Mixed Solvents

Warped factor analysis

Analytical Evaluation of Herbal Drugs

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