Deconvolution, species ratios

With time, the CW-EPR spectral pattern slowly changes the proportion of the components varies and a third component appears. The CW-EPR spectrum taken 1 h after mixing can be deconvoluted into the earlier-mentioned triplet and quintet, and into a septuplet at giSO,3 = 1.9793, rtfiSO,3 1.0 x 10" 4 cm 1 (=3.0 MHz)], in 6 3 1 ratio. Other minor species also appear, but they were not included in the simulations to avoid over-parameterization.87 Based on the H hyperfine coupling, the three components are suggested to correspond to [CrOti/.v-O1,02-29)21 (complex II,... 

There are two basic assumputions in factor analysis. First, the individual spectra of the components are not linear combinations of the other components and second that the concentration of one or more species cannot be expressed as a constant ratio of another species. It is the different relative concentrations of the components in the mixtures that provides the additional information necessary to deconvolute the spectra. 

The binding of 9-aminoacridine to calf thymus DNA has been studied at low ratios of dye/polymer [87]. Once the dye concentration levels were increased to the point where bound dye molecules could interact with each other, the spectra could be interpreted in terms of exciton coupling. In another system involving the same intercalation system [88], the observed spectra were deconvoluted into contributions from three n- w transitions and the dipole and rotatory strengths of one long-axis and one short-axis polarized transition were determined for each intercalating species. Through comparison of the experimental results with those of theoretical calculations on the induced CD, it proved to be possible to draw several conclusions about the nature of the intercalated species ... 

The mass spectra of 7, obtained from the NADPH/02/P-450 oxidation of 5, and 8 are compared in Table IV. Three isotopic species are expected for the allylic hydroxylation of 5. Oxidation with removal of hydrogen will produce 7-d3and 7a-d3. Extensive controls have demonstrated that 7-d3 and 7a-d3 are indistinguishable by mass spectrometry because of rapid 1,3-migration of the siloxy group upon electron impact. Oxidation with deuterium removal leads to the production of 7-d2 (Scheme 4). By this analysis, the isotope effect is simply the ratio of 5-d3 (and 5a-d3) to 5-d2 in the oxidized sample. Deconvolution of the parent region (with appropriate correction for carbon and silicon... 

Isotope ratio measurements were employed for the quantification of analytical data using the isotope dilution strategy. For example, isotope dilution analysis was developed by Sanz-Medel s group for the determination of selenomethionine in Se enriched yeast material by HPLC-ICP-MS using a Se-enriched selenomethionine spike obtained by growing yeast on a Se rich culture medium. For Cr(III)/Cr(VI) determination in yeast, Caruso et al employed the double spike species specific isotope dilution technique measured by HPLC-ICP-MS. The isotope pattern deconvolution approach applied in this work delivers a more intuitive and elegant solution to an otherwise complex data analysis without the need for iterative calculations as widely practised in double spike isotope dilution. The results are in exact agreement with the conventional isotope dilution calculations. ... 

XPS-analysis of surface exposed to the perfluorinated monomers showed the presence of all possible species regardless of monomer structure. Fig. 1 shows the deconvoluted carbon Is XPS spectrum of a poly(ethylene) surface after exposure of hexafluoropropylene in a glow discharge. A 1 1 1 ratio of the CF3, CF2 and CF groups was found suggesting the structure of a normal addition polymer. 

The deconvolution of multicomponent fluorescence spectra may be accomplished using a ratio method providing spectral regions may be located where the luminescence is due to one species only. ... 

The nitrogen content of the molybdenum nitride hydrodesulfurization catalysts was determined by x-ray phoioeleciron spectroscopy. The Mo 3d spectra were fitted into six sets of Mo doublets (Mo 3dv and 3ds ) with each fwhm corresponding to six different molybdenum species. The XPS N Is peak in the catalysts was deconvoluted with the individual Mo 3pt 2 signals based on the same distribution of the Mo 3d electrons of Mo 3p3 2 as the Mo 3d. 2 spectra. This method is accurate for the determination of the N/Mo ratio in molybdenum nitrides with a small error during hydrotlesulfurization reaction. 

In the area of imaging of different chemical species with various concentration ratios and for which the spectral widths are larger than the pixel spatial dimension, deconvolution was shown to be useful by Baldwin Barjat... 

An important improvement in the calculation procedure for species-specific multiple spiking was obtained by introducing isotope pattern deconvolution (IPD). The difference from the conventional multiple-spiking technique is the use of isotopic abundances instead of isotope ratios for calculation. The measurement of additional isotopes not used for calculation of interconversion reactions provides internal correction for mass bias effects without the application of an external isotopic standard, but also correction for spectral interferences. The basic equations applied in IPD can be found in the literature [78], This new method is predominantly applied in speciation analysis, but also in metabolism studies using stable isotopes [97, 98]. For quantification of elemental species, including... 

For measuring the relative amount of the different species, physical methods play the most important role since they do not influence their ratio. The impressive colours of the catalysts recommend the use of optical (reflectance) spectroscopy. In the chromium case, for example, the characteristic absorptions (Fig. 18.3) allow a deconvolution and - with certain assump-... 

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