Fourier transform infrared solvents

The role of specific interactions in the plasticization of PVC has been proposed from work on specific interactions of esters in solvents (eg, hydrogenated chlorocarbons) (13), work on blends of polyesters with PVC (14—19), and work on plasticized PVC itself (20—23). Modes of iateraction between the carbonyl functionaHty of the plasticizer ester or polyester were proposed, mostly on the basis of results from Fourier transform infrared spectroscopy (ftir). Shifts in the absorption frequency of the carbonyl group of the plasticizer ester to lower wave number, indicative of a reduction in polarity (ie, some iateraction between this functionaHty and the polymer) have been reported (20—22). Work performed with dibutyl phthalate (22) suggests an optimum concentration at which such iateractions are maximized. Spectral shifts are in the range 3—8 cm . Similar shifts have also been reported in blends of PVC with polyesters (14—20), again showing a concentration dependence of the shift to lower wave number of the ester carbonyl absorption frequency. 

Infrared spectroelectrochemical methods, particularly those based on Fourier transform infrared (FTIR) spectroscopy can provide structural information that UV-visible absorbance techniques do not. FTIR spectroelectrochemistry has thus been fruitful in the characterization of reactions occurring on electrode surfaces. The technique requires very thin cells to overcome solvent absorption problems. 

Deveaux M, Huvenne J-P. 1987. Identification of solvents of abuse using gas chromatography/fourier transform infrared spectrometry after headspace sampling. Chromatographia 23 626-630. 

Several modem analytical instruments are powerful tools for the characterisation of end groups. Molecular spectroscopic techniques are commonly employed for this purpose. Nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy and mass spectrometry (MS), often in combination, can be used to elucidate the end group structures for many polymer systems more traditional chemical methods, such as titration, are still in wide use, but employed more for specific applications, for example, determining acid end group levels. Nowadays, NMR spectroscopy is usually the first technique employed, providing the polymer system is soluble in organic solvents, as quantification of the levels of... 

IR spectra were obtained on a Model 10MX Nicolet Fourier Transform infrared spectrometer. IR films were spin-coated from polymer solutions in chlorobenzene on either KBr discs or silicon wafers polished on both sides. The samples were baked in vacuum at 90 C for at least 1 hour to ensure solvent removal. Film thicknesses were approximately 1 jtm, sufficient to remove interference fringe effects from the spectra. 

The possible accumulation of intermediates during the photocatalytic oxidation of aromatic contaminants has been studied with a variety of techniques, including temperature-progranuned desorption (TPD), oxidation (TPO), and hydrogenation (TPH), Fourier transform infrared analysis (FTIR), and extraction of adsorbed species with a variety of solvents. 

The isourea protocol was carried out in a 9 1 dichloromethane/N,N-dimethylf-ormamide (DCM/DMF) solvent mixture in sealed vessels, whereas the anhydride reactions were carried out in 1 -methyl-2-pyrrolidinone (NMP) under atmospheric pressure. In all experiments, the loading was estimated by on-bead Fourier transform infrared spectroscopy (FTIR) analysis and determined by cleavage from the PS Wang resin with 50% TFA in DCM. 

Several analytical techniques have been used to characterize the polymer/ silane coupling agent interphase. Culler et aL [2] used Fourier transform infrared (FT-IR) spectroscopy to characterize the chemical reactions at the matrix/silane interphase of composite materials. They correlated the extent of reaction of the resin with the coupling agent (as determined by FT-IR) with the extent of interpenetration. Culler et al. [2] have also used observations of improved resistance of the interphase region to solvent attack as indirect evidence to support the interpenetrating network theory. 

Several researchers have combined the separating power of supercritical fluid chromatography (SFC) with more informative spectroscopic detectors. For example, Pinkston et. al. combined SFC with a quadrupole mass spectrometer operated in the chemical ionization mode to analyze poly(dimethylsiloxanes) and derivatized oligosaccharides (7). Fourier Transform infrared spectroscopy (FTIR) provides a nondestructive universal detector and can be interfaced to SFC. Taylor has successfully employed supercritical fluid extraction (SFE)/SFC with FTIR dectection to examine propellants (8). SFC was shown to be superior over conventional gas or liquid chromatographic methods. Furthermore, SFE was reported to have several advantages over conventional liquid solvent extraction (8). Griffiths has published several... 

Chemical and instrumental (e.g., chromatography and mass spectrometry) methods have provided valuable information that lead to the advancement of cheese science. However, these techniques suffer from one or more of the following problems (1) the extensive use of solvents and gases that are expensive and hazardous, (2) high costs, (3) the requirement of specific accessories for different analytes, (4) the requirement of extensive sample preparation to obtain pure and clean samples, and (5) labor-intensive operation. These disadvantages have prompted for the evaluation and adoption of new, rapid, and simple methods such as Fourier-transform infrared (FTIR) spectroscopy. Many books are available on the basics of FTIR spectroscopy and its applications (Burns and Ciurczak, 2001 Sun, 2009). FTIR spectroscopy monitors the vibrations... 

There continues to be major problems with coupling HPLC to FTIR (Fourier transform infrared) due to the interference caused by water. The interface is the critical component in the system [126]. The two basic types of interfaces are continuous and capture. A continuous interface has been developed that uses a liquid-liquid extraction. In this approach, the analytes are extracted from the mobile phase by mixing postcolumn with a stream of IR (infrared) transparent, water-immiscible solvent. In the ca-pure technique, the eluent is deposited on a continuously moving, IR transparent, inert substrate from which the eluent can be easily removed by evaporation. These techniques have been applied to identification of racemic precursors of diltizam, AZT derivatives, and steroids [127]. 

Conventional Raman spectroscopy cannot be applied directly to aqueous extracts of sediments and soils, although it is occasionally used to provide information on organic solvent extracts of such samples. Fourier transform Raman spectroscopy, on the other hand, can be directly applied to water samples. The technique complements infrared spectroscopy in that some functional groups, eg unsaturation, give a much stronger response in the infrared. Several manufacturers (Perkin-Elmer, Digilab, Broker) now supply Fourier transform infrared spectrometers. 

Misra et al. [113] have reported the synthesis and optical/electrical properties of new 5-coordinated Al-complexes designed as Alq(l) and Alq(2). The complexes are vacuum evaporable as well as soluble in many organic solvents. EL peaks of these new complexes emit in the range 522-523 nm, which is nearly 8 nm blue shifted compared to that of Alq3. The chemical structures of the complexes were determined with the help of the Hydrogen Nuclear Magnetic Resonance (HNMR) and Fourier Transform Infrared (FTIR) spectroscopy techniques. The structure of these complexes is shown in Fig. 4.13. 

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