Magnetic composites infrared spectroscopy

GC and GC-MS (see Chapter 2), are ideal for the separation and characterization of individual molecular species. Characterization generally relies on the principle of chemotaxonomy, where the presence of a specific compound or distribution of compounds in the ancient sample is matched with its presence in a contemporary authentic substance. The use of such 6molecular markers is not without its problems, since many compounds are widely distributed in a range of materials, and the composition of ancient samples may have been altered significantly during preparation, use and subsequent burial. Other spectroscopic techniques offer valuable complementary information. For example, infrared (IR) spectroscopy and 13C nuclear magnetic resonance (NMR) spectroscopy have also been applied. 

The flame retardant mechanism of PC/ABS compositions using bisphenol A bis(diphenyl phosphate) (BDP) and zinc borate have been investigated (54). BDP affects the decomposition of PC/ABS and acts as a flame retardant in both the gas and the condensed phase. The pyrolysis was studied by thermogravimetry coupled with fourier transform infrared spectroscopy (FUR) and nuclear magnetic-resonance spectroscopy. Zinc borate effects an additional hydrolysis of the PC and contributes to a borate network on the residue. 

The synthesis of the complex is followed by the most important step of characterization of the complex. The composition and the structural features of both the ligand and complex have to be established before embarking on further studies. There exist many methods by which the composition and structural features of the complexes are studied. Some of the methods are (i) elemental analysis, (ii) X-ray crystallography, (iii) UV-Vis absorption spectra, (iv) infrared spectroscopy, (v) Raman spectroscopy, (vi) thermal methods of analysis such as thermogravimetry, differential thermal analysis, (vii) nuclear magnetic resonance spectroscopy (proton, multinuclear), (viii) electrospray mass spectrometry. Depending upon the complexity of the system, some or all the methods are used in the studies of complexes. 

Copolymer Analysis. Even though the overall copolymer composition can be determined by residual monomer analysis, it still is necessary to have reliable quantitative techniques for copolymer composition measurements on the actual copolymer, mainly because concentration detectors for SEC or HPLC are sensitive to composition and because the conversion histories are not always available. Some of the techniques used to determine copolymer composition are melt viscometry (46), chemical analysis, elemental analysis, infrared spectroscopy (IR), Nuclear Magnetic Resonance (NMR), ultra-violet spectroscopy (UV), etc. Melt viscometry, chemical and elemental analysis are general techniques that can be applied to almost any polymer. The spectroscopic techniques can be applied depending on the ability of the functional groups present to absorb at specific wavelengths. 

X-ray scattering, Mossbauer spectroscopy, infrared spectroscopy and magnetic susceptibility studies on the ferric hydroxynitrate polymer (approximate composition Fe4C>3(OH)4 (NC>3)2 1.5 H2O) shows that it is closely similar in those properties to the core of ferritin (180). It was also reported (72) that ferritin prepared from Fe2+ and apoferritin under oxidising conditions had a different morphology from native ferritin the iron micelle had a diameter of 48 A instead of 70 A and the overall diameter was 102 A instead of 120 A. 

Analysis of Composition of the Polymer and Additives Infrared Spectroscopy (IR), Energy Dispersive X-Ray Spectroscopy (SEM-EDX), Mass Spectrometry (MS), Gas Chromatography (GC), Nuclear Magnetic Resonance NMR)... 

In early systems, the eluates from the GC column were collected as separate fractions in a cold trap, and a nondestructive, nonsclective detector was used to indicate their appearance, The composition of each fraction was then investigated by nuclear magnetic resonance spectrometry, infrared spectroscopy, or by electroanalytical measurements. A serious limitation to this approach was the very small (usually micromolar) quantities of solute contained in a fraction,... 

Because the IV is a measure of the relative unsaturation of a compound or sample, other analytical techniques (e.g., gas chromatography of FA composition, AOCS Cd lc-85) can be used to estimate the value. Interest in recent years has focused on spectroscopic techniques for the rapid determination of TV. Fourier transform (FT)-near-infrared, near-infrared, FT-Raman, and H and nuclear magnetic resonance (NMR) spectroscopic techniques have all been investigated (Ng and Gee, 2001). The most promising results have been obtained with FT-near-infrared spectroscopy, which only takes a few minutes to determine the iodine value (Cox et al., 2000). 

Framework and Surfaces Since compositions and structures are very diverse, surface and framework properties are also extremely varied. In terms of compositions, coordination, and chemical environments, several methods are particularly informative for the characterization of nanoporous solids, such as nuclear magnetic resonance methods (NMR), UV-visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, x-ray absorption spectroscopies, x-ray photoelectron emission spectroscopy (XPS), and electron paramagnetic resonance (EPR) (4, 6). Among them, sohd state NMR techniques arc largely employed and will be briefly described in the following. 

Fire relstance,chemical composition by infrared (IR) and nuclear magnetic resonance (Mlffit) spectroscopy, thermal analyses, Clash-Berg moduli determination and dynamical mechanical analyses were determined. The fluorenone polyesters were spun as fibers from solution. They were blended with an acetylene terminated fluorenone monomer for plasticization and crosslinking at high temperatures to form an improved thermally stable product. 

Several spectroscopic methods have been used to monitor the levels of heavy metals in man, fossil fuels and environment. They include flame atomic absorption spectrometry (AAS), atomic emission spectroscopy (AES), graphite furnace atomic absorption sp>ectrometry (GFAAS), inductively coupled plasma-atomic emission sp>ectroscopy (ICP/AES), inductively coupled plasma mass spectrometry (ICP/MS), x-ray fluorescence sp>ectroscopy (XRFS), isotope dilution mass spectrometry (IDMS), electrothermal atomic absorption spectrometry (ETAAS) e.t.c. Also other spectroscopic methods have been used for analysis of the quality composition of the alternative fuels such as biodiesel. These include Nuclear magnetic resonance spectroscopy (NMR), Near infrared spectroscopy (NIR), inductively coupled plasma optical emission spectrometry (ICP-OES) e.t.c. 

Quantification of microbial PHA using GC method is rapid, sensitive, reproducible, and requires only small amount of samples (5-10 mg) for the analysis. Other techniques of analysis such as IR spectrometry at 5.75 A (Juttner et al. 1975), two-dimensional fluorescence spectroscopy, flow cytometry (Degelau et al. 1995) HPLC (Karr et al. 1983), ionic chromatography, and enzymatic determination (Hesselmann et al. 1999) were also desalbed. For online determination of PHA content in recombinant E. coli system, Fourier transform mid-infrared spectrometry (FTIR) and microcalorimetric technique (Ruan et al. 2007 Jarute et al. 2004) were also reported. For precise composition determination and structural elucidation of PHA, a variety of nuclear magnetic resonance (NMR) spectroscopy techniques have also been applied and the most commonly used are proton ( H) and carbon-13 ( C) NMR (Doi et al. 1986 Jacob et al. 1986). 

McCormick, C. L., Chen, G. S. and Hutchinson, B. H., Water-Soluble Copol3rmers. V. Compositional Determination of Random Copolymers of Acrylamide with Sulfonated Comonomers by Infrared Spectroscopy and C13 Nuclear Magnetic Resonance, J. Appl. Polym. Sci., 27 3103 (1982). 

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