Spectroscopy quantitation

Experimental Profile of Infrared Spectroscopy Quantitative Analysis... 

A plethora of pure drugs, their respective combinations and their dosage forms have been assayed by NMR-spectroscopy quantitatively by various researchers and the result(s) thus obtained were duly verified and compared with the standard methods prescribed in various official compendia. A few typical examples of such drugs shall be described briefly here ... 

With the recent progress in Fourier transform infrared (FTIR) spectroscopy, quantitative estimates of the various functional groups can also be made. This is particularly important for application to the higher-molecular-weight solid constituents of petroleum (i.e., the asphaltene fraction). 

A method of quantitatively determining 0.2% polyvinyl acetate in polystyrene has been described by Peitscher (1979) by using difference spectroscopy. Quantitative single component analysis of polymer films has been described by Chalmers et al. (1982). All samples were prepared by hot compression molding. This treatment produces a mat film surface, which suppresses interference fringes in the IR spectrum. For quantitative analysis it is essential that the thus produced films are homogeneous, of uniform thickness, and free of bubbles and irregularities. A clear section of each was chosen for the measurements. 

Bagawan, A. O., R. Muller-Fiedler, C. E. Brion, E. R. Davidson, and C. Boyle (1988). The valence orbitals of NH3 by electron momentum spectroscopy quantitative comparisons using Hartree-Fock limit and correlated wave-functions. Chem. Phys. 120, 335-57. 

Houseknecht D. W. (1991) Use of cathodoluminescence petrography for understanding compaction, quartz cementation, and porosity in sandstones. In Luminescence Microscopy and Spectroscopy Quantitative and Qualitative Applications (eds. C. E. Barker and O. C. Kopp). Society for Sedimentary Geology (SEPM), Tulsa, OK, Short Course vol. 25, pp. 59-75. 

The iron content of the produced samples was determined by X-ray fluorescence spectroscopy. Quantitative analysis was performed with the help of analytictJ standard and the results are listed in the second column of Table 1. 

Huggins, F.E. Huffman, G.P. Lee, R.J. Scanning Electron Microscope-Based Automated Image Analysis (SEM-AIA) and Moessbauer Spectroscopy — Quantitative Characterization of Coal Min er als. In Coal and Coal Products Analytical Characterization Techniques, Fuller, E.L. Jr., Ed. ACS SYMP. SERIES 205, American Chemical Society Washington, D. C., 1982, pp. 

The properties of a copolymer depend on its composition, monomer sequence and stereochemical structure. Although compositional analysis can be achieved by several methods other than NMR spectroscopy, quantitative data on monomer sequence distribution can only be obtained from NMR spectroscopy. I3C NMR chemical shifts of C=0 carbons of PMMA are sensitive to pentad to heptad stereochemical sequences. The C=0 carbon signals for the copolymers of methacrylates are also sensitive to triad comonomer sequence. Thus it should be difficult to assign both tactic and comonomer sequence signals, especially in the case of copolymers with low stereoregularity. 

S units by quantitative NMR spectroscopy (Quantitative C NMR of Lignins section) or from 2D HSQC spectra (Quantification in 2D NMR section). Other differences between GS lignins are frequently the presence of unique entities, such as incorporated hydroxycinnamates (Ferulates in Lignins Cell Wall Cross-Linking in Grasses by Ferulates section), and y-acylated units (p-Hydroxybenzoates in Various Flardwoods section) [309]. 

Products were analyzed by GLC on diisodecyl phthalate columns operated at 25°C. for 10 minutes, and programmed at 10°C./min. thereafter. Effluent fractions were trapped at 77 °K. and characterized further by ultraviolet, infrared, and mass spectroscopy. Quantitative analyses of B and DB, after the radiolysis of DB, were based on calibrations with synthetic mixtures. Polymer yields (solids of molecular weight comparable to or greater than that of perfluorobiphenyl) were determined as previously described (11). 19F NMR spectra were run in CC1 solution with CCI3F as internal reference. 

Abel E W, Coston T P J, Orrell K G, Sik Vand Stephenson D 1986 Two-dimensional NMR exchange spectroscopy. Quantitative treatment of multisite exchanging systems J. Magn. Reson. 70 34-53... 

Applications of Spark Source Spectroscopy Quantitative spark analyses demand precise control of (he many variables involved in sample preparation and excitation. In addition, quantitative measurements require a set of carefully prepared standards for calibration these standards should approximate as closely as possible the composition and physical properties of the samples to be analyzed, (iencrally, spark source analyses are based on the ratio of intensity of the analyte line to the intensity of an internal-standard line (usually a line of a major consliluciil >f the sample). Under ideal conditions, relative standard deviations of a few percent can be achieved with spark spectral measurements. 

The construction of a cell permitting both FTIR measurements and electrochemical impedance measurements at buried polymer/metal interfaces has been described [266]. Ingress of water and electrolyte, oxidation (corrosion) of the aluminum metal layer, swelling of the polymer and delamination of the polymer were observed. A cell suitable for ATR measurements up to 80°C has been described [267]. The combination of a cell for ATR measurements with DBMS (see Sect. 5.8.1) has been developed [268]. It permits simultaneous detection of stable adsorbed species and relatively stable adsorbed reaction intermediates (via FTIR spectroscopy), quantitative determination of volatile species with DBMS and elucidation of overall reaction kinetics. An arrangement with a gas-fed electrode attached to the ATR element and operated at T = 60°C has been reported [269]. In this study, the establishment of mixed potentials at an oxygen consuming direct methanol fuel cell in the presence of methanol at the cathode was investigated. With infrared spec-... 

The enantiomer and the racemic compound possess different crystal structures, which correspond to different intermolecular interactions, as mentioned in Sec. 3. Therefore the enantiomer and the racemic compound exhibit different powder x-ray diffraction (PXRD) patterns, different infrared (IR) and Raman spectra, and different solid-state nuclear magnetic resonance (SSNMR) spectra. However, the opposite enantiomers give identical PXRD patterns, and identical IR, Raman, and SSNMR spectra. Consequently, the PXRD patterns and the above spectra of a conglomerate, which is a physical mixture of opposite enantiomers, are identical to that of the pure enantiomers. In contrast, the diffraction pattern and the various corresponding spectra of the racemic compound usually differ significantly from those of the pure enantiomers. Therefore the type of racemate can be easily determined by comparing the diffraction patterns or the various spectra of the racemic species with that of one of the pure enantiomers (Figs. 3 5). The enantiomeric composition in a racemic mixture may be determined by PXRD, or by IR or SSNMR spectroscopy. Quantitative PXRD has been applied to determine the relative... 

The foremost spectroscopic techniques that yield information on the chemical state of adsoibates are optical (IRS, Raman, SFG, SHG), electron (EELS, XPS, UPS) and ion (SIMS) spectroscopies. Quantitative structural techniques such as LEED and XPD have also contributed to solving the question of the chemical state of the primary and secondary intermediate species. In this context, sections 1.4.3, 1.4.5-1.4.8 should also be consulted. 

Cr(VI) reduction takes place through Cr(V) spedes, readily complexed by citrate and detected by EPR spectroscopy. Quantitative EPR determinations indicate that an important fraction (nearly 15%) of the reduced Cr(VI) is transformed to Cr(V)-Cit, which also undergoes a photocatalytic transformation. 

Van Hecke P and Van Huffel S (eds.) (2001) NMR spectroscopy quantitation, special issue NMR in Biomedicine... 

RBS Rutherford Backscattering Spectroscopy Quantitative thin film composition and thickness Backscattered He atoms 0.001-10at% 20-200A 2mm... 

Anders AngstrOm in Uppsala Makes Spectroscopy Quantitative... 

Principles and Characteristics A wide variety of structural analysis tools is available employing X-rays (Table 5.59). Micro-focused X-ray sources allow small area spectroscopy, quantitative line scans and retrospective chemical state imaging based on high energy resolution spectra from user-defined areas. X-ray imaging complements electron imaging allowing to study relatively thick samples. 

LSPR Reflectance Spectroscopy, quantitative multivariate analysis and time constant analysis was performed as described in our papers (10, 11). 

Bonetti, A., Apostoli, P, Zaninelli, M., Pavanel, F., Colombatti, M., Cetto, G. L., Franceschi, T., Sperotto, L., and Leone, R. (1996) Inductively coupled plasma mass spectroscopy quantitation of platinum-DNA adducts in peripheral blood leukocytes of patients receiving cisplatin or carboplatin based chemotherapy. Clin. Cancer Res., 2,1829-35. 

Albin M, Horrocks WD Jr., Europium(III) luminescence excitation spectroscopy, quantitative correlation between the total charge on the ligands and the Fq Dq transition frequency in Europium (III) complexes. Inorg Chem. 1985 24(6) 895-900. 

As far as the quantitative evaluation of vibrational spectra is concerned, IR and NIR spectroscopy follow Beer s law, whereas the Raman intensity JRaman is directly proportional to the concentration of the compound to be determined (Figure i),i iS Si To compensate laser fluctuations, in many cases, quantitative Raman spectroscopy is performed with an internal reference signal in the vicinity of the analytical band. For Raman and IR spectroscopy, quantitative analysis can be performed by either univariate evaluation of band heights/ areas or multivariate evaluation (e.g., partial least-squares (PLS) regression) of large spectral regions. Due to the overlap of many absorption bands for the quantitative analysis of NIR spectra, predominantly multivariate chemometric procedures are applied. For an in-depth study of the precautions, pitfalls, and limitations, which have to be observed or may be encountered in the measurement of vibrational spectra, the reader is referred to the pertinent literature. " ... 

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