Pyrolysis gas chromatograph

It has been reported that pyrolysis gas chromatographic techniques could be used to differentiate between block and random copolymers (18). However, it was not possible to distinguish between the block copolymers and mixtures of polystyrene and the alternating copolymers of styrene and maleic anhydride by the PGC technique used in this investigation. However, differences were noted in the DTA thermograms of the alternating copolymer, the block copolymer, and the mixture of polystyrene and the alternating copolymer. 

Pyrolysis gas chromatographic investigations were made using a Wilkins model A100C aerograph equipped with a Servo-Ritter II Texas instrument recorder using helium as the carrier gas. The 10 ft X 1/4 inch diameter column was packed with acid washed chromosorb W (Johns Manville) with 20% SE-20 (General Electric Co.). 

Perry, S. G. Identification of microgram quantities of zinc dialkyl dithiophos-phates. A pyrolysis-gas chromatographic technique. J. Gas Chromatog. 2, 93 (1964). 

Maruyama et al. reported the use of a simple pyrolysis gas chromatographic method for the determination of choline and acetylcholine in brain tissue [136]. Schmidt and Speth reported a simultaneous analysis of choline and acetylcholine levels in rat brain tissue by a pyrolysis gas chromatographic method [137], Kosh et al. reported an improved gas chromatographic method for the analysis of acetylcholine and choline in rat brain tissue [138], Mikes et al. used a syringe micro-pyrolyzer for the gas chromatographic determination of acetylcholine, choline and other quaternary ammonium salts [139],... 

A number of multidimensional analyses have been developed that provide powerful methods for characterizing these polymers. Linking a liquid chromatogram to a pyrolysis gas chromatograph [l 9] can determine the breadth of the composition distribution, as the method fractionates the SAN copolymer before pyrolysis. This information is useful for determining the source of variation in SAN copolymer properties. Composition drift towards high acrylonitrile-containing fractions can lead to undesirable yellow color, and excessively broad composition drift can cause opacity and brittleness in the material due to phase separation... 

S. J. Evans, P. J. Haines and G. A. Skinner, Pyrolysis-gas-chromatographic study of a series of polyester thermosets. J. Anal. Appl. Pyrolysis, 55, 13-58, (2000). 

Figure 8. Pyrolysis gas chromatographs of size fractions A) 0.45-0.1 micrometers and B) 3K-1K molecular weight of samples obtained from Saganashkee Slough. Marker compounds and retention times are 1) acetonitrile, 5.97 min 2) thiophene, 6.10 min, and toluene, 6.33 min 3) anisole, 11.90 min 4) acetic acid, 13.82 min 5) pyrolle, 15.64 min 6) acetamide, 20.34 min 7) phenol and o-cresol, 25,18 min 8) m-cresol and p-cresol, 26.67 min and 9) indole, 32.53 min.

When the major alkaloid in tobacco samples is nor-nicotine, the commonly used steam-distillation method and automated procedures result in poor estimates of nicotine and nornicotine. Rosa18 therefore developed a pyrolysis-gas chromatographic method, whereby pyrolysis was carried out with a Victoreen pyrolyzer fitted to the gas chromatograph. Nicotine is relatively volatile and readily released by pyrolysis, even at 100°C. Nornicotine, being less volatile, showed maximum release by pyrolysis at 300°C. The pyrolysis-gas chromatography was carried out with ca. 1 mg of tobacco. The results obtained with the method are presented in Figure 5.3. 

Amorphous and semi-crystalline polypropylene samples were pyrolyzed in He from 388°-438°C and in air from 240°-289°C. A novel interfaced pyrolysis gas chromatographic peak identification system was used to analyze the products on-the-fly the chemical structures of the products were determined also by mass spectrometry. Pyrolysis of polypropylene in He has activation energies of 5-1-56 kcal mol 1 and a first-order rate constant of JO 3 sec 1 at 414°C. The olefinic products observed can be rationalized by a mechanism involving intramolecular chain transfer processes of primary and secondary alkyl radicals, the latter being of greater importance. Oxidative pyrolysis of polypropylene has an activation energy of about 16 kcal mol 1 the first-order rate constant is about 5 X JO 3 sec 1 at 264°C. The main products aside from C02, H20, acetaldehyde, and hydrocarbons are ketones. A simple mechanistic scheme has been proposed involving C-C scissions of tertiary alkoxy radical accompanied by H transfer, which can account for most of the observed products. Similar processes for secondary alkoxy radicals seem to lead mainly to formaldehyde. Differences in pyrolysis product distributions reported here and by other workers may be attributed to the rapid removal of the products by the carrier gas in our experiments. 

Interfaced Pyrolysis Gas Chromatographic Peak Identification System (IPGCS). The versatile IPGCS (5) incorporates instrumentation... 

Figure 1. Block diagram of the interfaced pyrolysis gas chromatographic peak...

A novel interfaced pyrolysis gas chromatographic peak identification system has been used to study the pyrolysis and oxidative pyrolysis of... 

The combination of a SPME device with a pyrolysis gas chromatographic (GC) IMS system improved the limit of detection of tributylphosphate (TBP, which served as a simulant) in water by a factor of 20 compared to the same system without the SPME device. SPME fibers were also used to sample headspace vapors of several types of nerve agents, and the fibers were introduced directly into a modified ESI source for subsequent detection by IMS and mass spectrometry (MS). A SPME-IMS system, with thermal desorption, was also used to screen soil samples for precursor and degradation products of CWAs, and it was found that fibers of polydimethyl-siloxane (PDMS) were superior to PDMS-divinylbenzene fibers. ... 

Shedrinsky, A.M., R.E. Stone, and N.S. Baer, Pyrolysis gas chromatographic studies on Egyptian archaeological specimens organic patinas on the three princesses gold vessels, J. Anal. Appl. Pyrol., 20 229—238 (1991). 

Feller, K.L., Dammar and mastic infrared analysis. Science, 120 1069-1070 (1954). Shedrinsky, A.M., D. Grimaldi, T.R Wampler, and N.S. Baer, Amber and copal pyrolysis gas chromatographic (PyGC) studies of prevenance, Wiener Berichte fiber Naturwissenschaft in der Kunst, 6niS (1989/90/91), pp. 37—62. van Aarssen, B.G.K., J.W. de Leeuw, and B. Horsfield, A comparative study of three different pyrolysis methods used to characterize a biopolymer isolated from fossil and extant dammar resins, J. Anal. Appl. PyroL, 20 125-139 (1991). 

Thomas, T.H. and T.C. Kendrick, Thermal analysis of polydimethylsUoxanes. I. Thermal degradation in controlled atmospheres, J. Polym. Sci. A, 27 537 (1969). Blazsd, M., G. Garzo, and T. Szekely, Pyrolysis gas chromatographic studies on polydimethylsiloxanes and polyfdimethyl sUalkylene siloxanes), Chromatographia, 5 485 (1972). 

Kleinert, J.C. and C.J. Weschler, Pyrolysis gas chromatographic-mass spectrometric identification of poly (dimethylsiloxanes). Ana/. Chem., 52 1245 (1980). 

Rosa N (1979) Pyrolysis-gas chromatographic estimation of tobacco alkaloids and neophytadiene. J Chromatogr 171 419-423... 

Cope [147] has described a pyrolysis/gas chromatographic procedure for the determination of tetrakis(hydroxymethyl)phosphonium hydroxide and tris(2,3-dibromo-propyl)phosphate flame retardants on polyesters and surface tris(2,3-dibromopropyl)phosphate have been determined on the surface of retardant polyester fabrics [148]. The technique used to determine these, involved extraction of the fabric with an organic solvent followed by analysis of the solvent by X-ray fluorescence for surface bromine and by high pressure liquid chromatography for molecular tris(2,3-dibromopropyl)phosphate. 

The pyrolysis-gas chromatographic technique has been used to identify microgram amounts of zinc dialkyidithiophosphates, isolated from mineral oils. (Perry )... 

The pyrolysis-gas chromatographic apparatus is shown schematically in Figure 7. The pyrolysis vessel is shown in Figure 8. 

Barrall and co-workers [46] described a pyrolysis-gas chromatographic procedure for the analysis of polyethylene-ethyl acrylate and polyethylene-vinyl acetate copolymers and physical mixtures thereof. They used a specially constructed pyrolysis chamber as described by Porter and co-workers [47]. Less than 30 seconds is required for the sample chamber to assume block temperature. This system has the advantages of speed of sample introduction, controlled pyrolysis temperature, and complete exclusion of air from the pyrolysis chamber. The pyrolysis chromatograph of poly(ethylene-vinyl acetate) contains two principal peaks the first is methane and the second is acetic acid ... 

Folmer [15, 16] studied the effects of different operating conditions and methods of sample preparation on fragmentation patterns. Clear or translucent samples give reproducible results if mixed with carbon. This laser pyrolysis - gas chromatographic technique is used to identify unknown polymers from the pattern of the breakdown products of their pyrolysis products. 

Sharp and Paterson [41] have described a pyrolysis - gas chromatographic - mass spectrometric procedure for the determination of 1-10% of copolymerised acrylic acid and methacrylic acid in acrylic polymers (see Method 3.5). The acid groups are propylated and the polymer pyrolysed according to the following reaction scheme ... 

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