Pyrolysis gas chromatographic techniques

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. 

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

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

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. 

This laser pyrolysis gas chromatographic technique is used to identify unknown polymers from the pattern of the breakdown products of their pyrolysis products. 

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. 

Pyrolysis gas chromatography (PGC) was one of the first combination gas chromatographic techniques, yet it is still plagued by problems of accuracy and repeatability of pyrolysis conditions and laboratory-to-laboratory reproducibility. There are three major devices for PGC (1) heated wire or ribbon, (2) tube furnace, and (3) Curie point filament. The heated wire or ribbon apparatus uses resistive heating to provide flash pyrolysis from ambient temperature to 1400°C. It can be controlled to reach the maximum temperature in milhseconds or at some fixed rate, and the device can hold the top temperature for a settable fixed time. These high-precision devices can be placed directly in the injection port (for vertical injection ports). The temperature reading should be checked from time to time to ensure accuracy. 

Van Schooten and Evenhuis [142, 143] applied their pyrolysis (500 C) -hydrogenation-gas chromatographic technique to unsaturated ethylene-propylene... 

The techniques most commonly used in thermo-oxidative studies on polymers are mainly based on thermal analysis methods such as thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) and on pyrolysis-gas chromatographic studies (particularly if they are linked to complimentary techniques such as mass spectrometry or infrared spectroscopy). Other techniques that have been used to a much lesser extent include chemiluminescence analysis, nuclear magnetic resonance (NMR) spectroscopy, electron spin resonance, and positron annihilation lifetime mass spectrometry. 

Another chromatographic method is pyrolysis/gas-liquid chromatography. The sample is mixed with P205 and heated to 400°C. This technique yields the chain length distribution of the fatty acids initially used [107],... 

One of the main problems of the pyrolysis technique is related to the low volatility of pyrolysis products arising from natural and some synthetic macromolecules. In fact, the polar acidic, alcoholic and aminic moieties are not really suitable for gas chromatographic analysis. Their poor volatility and their polarity cause a rather low reproducibility of the pyrograms, low sensitivity for specific compounds, and strong memory effects. Memory effects need to be borne in mind when the pyrolysis of polar molecules is performed. Polar pyolysis products may not be completely eluted by the gas chromatographic column, and... 

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