Experimental IR spectroscopy of polymers

Koenig, Jack L.

doi:10.1016/b978-044410031-3/50003-7

Cited by 20 publications

(13 citation statements)

References 111 publications

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“…Spectral deconvolution was performed to resolve overlapping bands. Deconvolution21 enhances the apparent resolution of overlapping peaks when the limiting resolution is the natural width of the bands, and not the resolution of spectrum acquisition. This helps in identifying the principal bands comprising of a more complex band with overlapping features, and can be useful to sharply determine the number of peaks and the band positions in a region.…”

Section: Methodsmentioning

confidence: 99%

Dependence of water uptake and morphology of hyaluronan- and alginate-based hydrogels on pH and degree of crosslinking

Barbucci

Consumi

Magnani

2002

Macromol. Chem. Phys.

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Hydrogels of alginate and hyaluronan with 5%, 50% and 100% crosslinking, (percentage of polysaccharide carboxylate groups involved in crosslinking) are synthesized. Crosslinking and stoichiometry were varied by appropriate addition of chloromethylpyridine iodide (CMPI) to activate the carboxylic groups. Crosslinking percentage was determined by potentiometry, i.e., titrating the free carboxylate groups of the polysaccharide. Water uptake by the gels is studied in relation to crosslinking and pH. Hydrogen bonds in the three‐dimensional network, as shown by FT‐IR spectroscopy, are used to explain differences in water uptake and their dependence on pH. Scanning electron microscopy (SEM) analysis of the gels is performed at different pHs and the morphologies are compared with their chemical structures.

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Section: Methodsmentioning

confidence: 99%

Dependence of water uptake and morphology of hyaluronan- and alginate-based hydrogels on pH and degree of crosslinking

Barbucci

Consumi

Magnani

2002

Macromol. Chem. Phys.

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“…The positions of the bands in the regions of 4000-3000 and 950-600 cm -~ are very similar to those found in the KBr-pellet spectrum. The observed frequencies of the Si-O stretching vibrations near 1000 cm -~ are shifted slightly downward from those observed in IR transmission spectroscopy as a result of the optical physics of the system (Koenig, 1992;Rintoul et al, 1998). The ATR is a rapid, non-destructive technique and is a very useful first step to characterize minerals.…”

Section: Comparison Of the Sample-preparation Methodsmentioning

confidence: 99%

“…The greater sensitivity of the FTIR spectrometers is related to the continuous detection of the entire transmitted energy simultaneously, using interferometers, and rapid Fourier transformation of the interferogram into a spectrum (Koenig, 1992;Russell and Fraser, 1994). The increased sensitivity of FTIR spectrometers led to the development and recent broad application of reflectance techniques, such as ATR and DRIFT (Griffiths and de Haseth, 1986).…”

Section: Introductionmentioning

confidence: 99%

Baseline Studies of the Clay Minerals Society Source Clays: Infrared Methods

Madejová

Komadel

2001

Clays and clay miner.

1,017

425

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Infrared (IR) spectroscopy has a long and successful history as an analytical technique and is used extensively (McKelvy et al., 1996; Stuart, 1996). It is mainly a complementary method to X-ray diffraction (XRD) and other methods used to investigate clays and clay minerals. It is an economical, rapid and common technique because a spectrum can be obtained in a few minutes and the instruments are sufficiently inexpensive as to be available in many laboratories. An IR spectrum can serve as a fingerprint for mineral identification, but it can also give unique information about the mineral structure, including the family of minerals to which the specimen belongs and the degree of regularity within the structure, the nature of isomorphic substituents, the distinction of molecular water from constitutional hydroxyl, and the presence of both crystalline and non-crystalline impurities (Farmel, 1979).

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“…7 where S 1 and S 2 are the discrete spectra being compared, each being first normalized (indicated by ^), and where ⋆ indicates the cross-correlation function, are used as calculated. 46–48 These expressions can generate a normalized similarity index in the range between 0 and 1 indicating no similarity to perfect matching, respectively, by subtracting from 1 in the case of the difference sum of squares calculation, and fractional difference relative to the self-correlation on one of the two spectra in the case of the cross-correlation calculation.…”

Section: Similarity Indexmentioning

confidence: 99%

Spectral Analysis and Deconvolution of the Amide I Band of Proteins Presenting with High-Frequency Noise and Baseline Shifts

2020

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The challenge of deriving quantitative information from the infrared spectra of proteins arises from the large number of secondary structures and amino acid side-chain functional groups that all contribute to the spectral intensity, such as within the amide I band (1600–1700 cm–1). The band is invariably heavily convoluted from overlapping spectral features, thereby making interpretation difficult such that deconvolution is usually required. This work critically examines the methods available to deconvolute the spectra and assesses the commonly used methods and algorithms applied to vibrational spectra for smoothing and peak identification. We show that unless their spectra have very high signal-to-noise ratios, quantitative analysis to decipher protein constituents is not feasible. The advantages and disadvantages of spectral smoothing using adjacent averaging, the Savitzky–Golay filter and the fast Fourier transform filter are examined in detail. The use of derivative spectra to identify peaks is described with particular reference to the influence and reduction of interfering water bands in the amide I region. The reliability of band narrowing techniques such as second-derivative analysis or Fourier deconvolution that lead to the identification of the contributing protein peaks is investigated. Both methods are shown to be limited in their capacity to resolve features with very similar frequencies. Additionally, the presence of narrow bands arising from high-frequency noise whether from atmospheric water vapor, acoustic vibrations, or electrical interference results in both methods becoming increasingly unusable as narrow bands are preferentially enhanced at the expense of broad ones such as the amide I bands. An optimal strategy is critically developed to allow accurate determination and quantification of protein constituents and their conformations. Additionally, quantitative methods are proposed to account for baseline shifts, which would otherwise introduce significant errors in similarity indices.

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Experimental IR spectroscopy of polymers

Cited by 20 publications

References 111 publications

Dependence of water uptake and morphology of hyaluronan- and alginate-based hydrogels on pH and degree of crosslinking

Dependence of water uptake and morphology of hyaluronan- and alginate-based hydrogels on pH and degree of crosslinking

Baseline Studies of the Clay Minerals Society Source Clays: Infrared Methods

Spectral Analysis and Deconvolution of the Amide I Band of Proteins Presenting with High-Frequency Noise and Baseline Shifts

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