Mass spectroscopy , degradation analysis

We have followed the pathway of TNT degradation in the consortium using reverse phase high performance liquid chromatography (HPLC) and mass spectroscopy (MS). Analysis of the supernatant in the consortium showed sequential reduction of TNT to TAT however, TAT only occasionally accumulated, and even then only in very low concentrations. In addition, methylphloroglucinol (MPG) and />-cresol transiently appeared in the supernatant. All compounds were identified using HPLC by UV spectra and retention times as compared to authentic standards chromatographed under the same conditions. The mono- and diamino intermediates were also confirmed by the MS results. 

Figure 5.10 is the dynamic TGA scan of neat PTFE in air and N2. Under each atmosphere studied, it is readily apparent that the onset of degradation occurs at about 500°C. TGA data are also in excellent agreement with a more sensitive and structurally informative pyrolysis/mass spectroscopy analysis. Figure 5.11 is a... 

Recently, MS combinations have been available including the thermogravimetric analysis mass spectroscopy (TG-MS) combination developed by Carraher that allows the continuous characterization of evolved materials as a polymer undergoes controlled thermal degradation. 

Fig. 14.1 A principal scheme of the experiment in vitro. The solution, where the substrate is mixed with proteasome, is analyzed for different moments of time. Mass spectroscopy or fluorescence analysis then shows how much substrate has been degraded and which fragments have been produced.

The most frequently used techniques for the structural elucidation of photodegradation products are IR spectroscopy, mass spectrometry, elemental analysis, and nuclear resonance spectroscopy. Degradation products for use with these methods... 

Early studies on one of the plants, Ceanothus americanus, showed the alkaloid fraction to be a complex mixture of closely related compounds, as has since been found to be true for most of the other plants examined. Little real progress in the chemistry of these compounds was possible until the recent development of the more refined separation and analytical techniques of thin-layer chromatography, n.m.r., and organic mass spectroscopy. The structures of the first few bases (pandamine, zizyphine, ceanothine-B, scutianine, and the adouetines ) were determined by a combination of chemical degradation and applied spectroscopy. More recently, automatic amino-acid and mass spectroscopic analysis of these... 

The 2D gel or Iso-Dalt is the most commonly used method in proteomics because of its relatively easy use, automation, high reproducibility, high resolution of proteins, and applicability to analysis by mass spectroscopy. Furthermore, protein bands separated by Iso-Dalt are readily amenable to Edman degradation or to the amino acid composition analysis. 

HPLC is now considered to be an established standard technique in most Preformulation and Formulation laboratories. We use HPLC to assess the degradation of the compound in the solid or solution state. From our measurements, we should be able to determine, e.g., the kinetics of degradation. Furthermore, if we can identify the degradation products of the reaction by combining this technique with mass spectroscopy, then it may also be possible to elucidate the degradation mechanism. The advantages of HPLC lie in the combination of sensitivity, efficiency, reliability and speed of analysis of the technique. Only brief guidance is... 

Complex GIPCs have been purified from encapsulated (WT) and acapsular (Cap67) cells of C. neoformans [77], Their structures were determined by a combination of tandem mass spectrometry, nuclear magnetic resonance spectroscopy, methylation analysis, GC-MS, and chemical degradation. Chemical analysis of the erode GIPCs isolated from... 

The isolation of coprine (20) and its structure determination was reported recently by two different groups (94,201, 202). In one large-scale isolation 7.3 g of crystalline coprine was obtained from 62.5 kg of Coprims atramentarius by ion-exchange chromatography (202). The second isolation described gave 12 mg of coprine as an amorphous solid from 10 g of the mushrooms (94). The structure was established by elementary analysis, PMR-spectroscopy at 100 and 220 MHz, C-NMR-spectroscopy and mass spectroscopy, and by various degradation reactions. 

CoupiGd Pyrolysis Techniques. Perhaps the most powerful techniques currently available are those in which the polymer is pyrolyzed for a short time in a pyrolysis system directly coupled to a modem analytical instmment capable of analysis of the volatile products. Although direct pyrolysis coupled with ftir is available, the most common techniques have been gas chromatography, mass spectroscopy, and combinations of the two. In contrast to tga, these techniques provide no real information on the onset temperature of degradation or on the number of distinct stages, but they can give very detailed information about the products of reaction. 

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