Analysis pyrolytic

Besides whole microorganisms that were analyzed by pyrolytic techniques, a variety of preparates were also subject to this type of analysis. Cell walls, capsular extracts or other specific extracts were the subject of pyrolytic analyses. Significant differences can be seen between different preparates, and this imposes another requirement for pyrolytic analysis with taxonomic purposes. The reproducibility of the technique for obtaining the preparates must be very good in order to avoid sample contamination with unwanted cell components. 

Gaseous Evolution of Molecular Hydrogen and Oxygen, Mass Spectrometric and Pyrolytic Analyses... 

In Figure 8, the pyrolytic analyses of two photolysis experiments in which the photochemical reaction was carried out for five and 15 minutes (respectively shown in Figures 8a and 8b) are compared with a corre-... 

Figure 8. Comparison of pyrolytic analyses of the photolysis and electrolysis of water at pH = 3. (a,b) Illumination of the Pt-Chl a sample with the entire output of a 1000 W tungsten-halogen lamp for 5 and 15 min, respectively, (c) Lower, hydrogen generated by passing 10 mA for 20 sec middle, oxygen generated by passing a current of 10 mA for 20 sec upper, sum of middle and lower curves.

While such thermal pyrolytic analyses are themselves useful, much of the functionality of the SATVA technique lays... 

CNs, the Fe ion is postulated to be coordinated by one SO and a mixture of CO and CNs. The interpretation is based on the temperature factor refinement and pyrolytic analysis of oxidized sulfur species (33). In addition, the bridging ligand is postulated to be an inorganic sulfur ion (instead of an oxo ligand, as proposed for the D. gigas). This... 

Finally there are the composite materials that are not uniform but do have identifiable component parts. These component parts can usually be separated and analyzed individually. However, this is not always the chosen procedure for their analysis. Analytical pyrolysis has been applied to composite materials as well as to uniform polymers, depending on the purpose of the analysis. Some examples of the pyrolytic analysis of natural organic composite materials are presented in Part 3 of this book. 

Generally, the distribution of the bound DDT-related compounds was found to differ distinctly from the distribution within the extractable fraction. The main metabolite of the anaerobic degradation pathway (2,2-bis(chlorophenyl)-l,l-dichlorethane, DDD) is most abundant in the sediment extracts, but occurred only in insignificant concentrations in the degradation products of all procedures applied. The most abundant DDT-metabolites released after the degradation procedures were 4,4 -DBP, 4,4 -DDA and 4,4 -DDM. In addition, 4,4 -DDM was detected at rather high concentrations by pyrolytic analysis. 

Authors speculate that the nonflammable effect might be caused by the following mechanisms through their fundamental studies of the gas analysis and pyrolytic analysis of the electrolytes ... 

Table 9.13 Pyrolytic analysis of HCl from PVC compounds and chlorinated PVC ...

Data such as that shown in Figure 13.21 is typical from the pyrolytic analysis of silicones. A homologous series of cyclic siloxanes from Dj to oligomeric with the D (thermodynamic) product being the most abundant, generally is observed. As with TVA analysis, there are also a large number of minor and trace products that are identifiable. In line with previous work, an examination of the dataset obtained... 

The former example demonstrated that Py-GC/MS methodologies can effectively discriminate between specific network architectures in simple model silicone systems as a function of their degradation chemistry. Significantly, it has also recently been demonstrated [53] that valid structure property correlations can be drawn from the pyrolytic analysis of complex, commercial and specialist application engineering silicones. 

Chemical Analysis. The presence of siUcones in a sample can be ascertained quaUtatively by burning a small amount of the sample on the tip of a spatula. SiUcones bum with a characteristic sparkly flame and emit a white sooty smoke on combustion. A white ashen residue is often deposited as well. If this residue dissolves and becomes volatile when heated with hydrofluoric acid, it is most likely a siUceous residue (437). Quantitative measurement of total sihcon in a sample is often accompHshed indirectly, by converting the species to siUca or siUcate, followed by deterrnination of the heteropoly blue sihcomolybdate, which absorbs at 800 nm, using atomic spectroscopy or uv spectroscopy (438—443). Pyrolysis gc followed by mass spectroscopic detection of the pyrolysate is a particularly sensitive tool for identifying siUcones (442,443). This technique rehes on the pyrolytic conversion of siUcones to cycHcs, predominantly to [541-05-9] which is readily detected and quantified (eq. 37). 

The surface analyses of the Co/MgO catalyst for the steam reforming of naphthalene as a model compound of biomass tar were performed by TEM-EDS and XPS measurements. From TEM-EDS analysis, it was found that Co was supported on MgO not as particles but covering its surface in the case of 12 wt.% Co/MgO calcined at 873 K followed by reduction. XPS analysis results showed the existence of cobalt oxide on reduced catalyst, indicating that the reduction of Co/MgO by H2 was incomplete. In the steam reforming of naphthalene, film-like carbon and pyrolytic carbon were found to be deposited on the surface of catalyst by means of TPO and TEM-EDS analyses. 

The TEM images of deposits observed on Catalyst I used for the steam reforming of naphthalene are shown in Fig. 5. Two types of deposits were observed and they were proved to be composed of mainly carbon by EDS elemental analysis. One of them is film-like deposit over catalysts as shown in Fig. 5(a). This type of coke seems to consist of a polymer of C H, radicals. The other is pyrolytic carbon, which gives image of graphite-like layer as shown in Fig. 5(b). Pyrolytic carbon seems to be produced in dehydrogenation of naphthalene. TPO profile is shown in Fig. 6. The peaks around 600 K and 1000 K are attributable to the oxidation of film-like carbon and pyrolytic carbon, respectively [11-13]. These results coincide with TEM observations. 

Asplla, K. I., Chakrabartl, C. L., and Bratzel, M. P., Jr. "Pyrolytic Graphite-Tube Micro-Furnace for Trace Analysis by Atomic Absorption Spectrometry". Anal. Chem. (1972),... 

Isolation may occur by liquid-solid interaction (extraction, dissolution) or heat (thermal, pyrolytic, laser). Extraction methods easily handle qualitative screening for low- to medium-MW compounds fail for high-MW components or polymer-bound functionalities and are less reliable quantitatively (analyte dependent). When applicable, dissolution methods suffer from sensitivity, because of the dilution effect on account of the polymer. In-polymer analysis performs well for qualitative screening, but is as yet not strongly performing for quantitative analysis, except for some specific questions. 

High Resolution Transmission Electron Microscopy (HRTEM, Philips CM20, 200 kV) was applied to get structural and nanotextural information on the fibers, by imaging the profile of the aromatic carbon layers in the 002-lattice fringe mode. A carbon fiber coated with pyrolytic carbon was incorporated in epoxy resin and a transverse section obtained by ultramicrotomy was deposited on a holey carbon film. An in-house made image analysis procedure was used to get quantitative data on the composite. 

Figure 6. Histogram of the fringes length obtained by computer analysis of the HRTEM image of the fiber/pyrolytic carbon composite.

The models incorporate two microscopic parameters, the site density and the critical nucleus size. A fit of experimental current transients to the models allows conclusions, for example, concerning the effect of additives on nucleation rate. Fabricus et al. found by analysis of current transients that thiourea increases the nucleation density of copper deposited on glassy carbon at low concentration, but decreases it at higher concentration [112], Schmidt et al. found that Gold nucleation on pyrolytic graphite is limited by the availability of nucleation sites [113], Nucleation density and rate were found to depend on applied potential as was the critical nucleus size. Depending on concentration, critical nuclei as small as one atom have been estimated from current transient measurements. Michailova et al. found a critical nucleus of 11 atoms for copper nucleation on platinum [114], These numbers are typical, and they are comparable to the thermodynamic critical radii [86],... 

A method has been developed for differentiating hexavalent from trivalent chromium [33]. The metal is electrodeposited with mercury on pyrolytic graphite-coated tubular furnaces in the temperature range 1000-3000 °C, using a flow-through assembly. Both the hexa- and trivalent forms are deposited as the metal at pH 4.7 and a potential at -1.8 V against the standard calomel electrode, while at pH 4.7, but at -0.3 V, the hexavalent form is selectively reduced to the trivalent form and accumulated by adsorption. This method was applied to the analysis of chromium species in samples of different salinity, in conjunction with atomic absorption spectrophotometry. The limit of detection was 0.05 xg/l chromium and relative standard deviation from replicate measurements of 0.4 xg chromium (VI) was 13%. Matrix interference was largely overcome in this procedure. 

Three Zeeman-based methods for the determination of cadmium in seawater were investigated. Direct determinations can be made with or without the use of a pyrolytic platform atomisation technique. The wall atomisation methods presented were considerably faster than the platform atomisation technique. For extremely low levels of cadmium, indirect methods of analysis employing a preliminary analyte extraction can be employed. Background levels are minimal in extracted samples, and the total furnace programme time was the lowest of the methods examined. 

Montgomery and Peterson [675] showed that ammonium nitrate used as a matrix modifier in seawater analysis to eliminate the interference of sodium chloride degrades the pyrolytic coating on graphite-furnace tubes. The initially enhanced sensitivities for copper, manganese, and iron are maintained for up to 15 atomisations. There is then a rapid decline to a constant lower sensitivity. The characteristics depend strongly on the particular lot of furnace tubes. To... 

From the CGC and CGC/MS analysis of the thermally initiated reactions of HDPE and PP with DBDPO and a variety of other components reported here, it has been shown that attack of polymer chain radicals on the DBDPO is the most probable first mechanistic step in the ternary mixture pyrolytic degradation of DBDPO. 

Thermogravimetric analysis (TGA) measures cellulose pyrolytic mass loss rates and activation parameters. The technique is relatively simple, straightforward and fast, but it does have disadvantages. One disadvantage is that determination of the kinetic rate constants from TGA data is dependent on the interpretation/analysis technique used. Another disadvantage of TGA is that the rate of mass loss is probably not equivalent to the cellulose pyrolysis rate. 

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