Pyrograms INDEX

The pyrograms of plants or lignins can be evaluated through use of the similarity index (Salo et al, 1989), as defined by the following equation ... 

The SI values can be used for comparing the pyrogram of an unknown sample and that of a known substance, and for determining the reproducibility of the pyrolysis system. Within the same laboratory, a similarity index of 95% for two consecutive Py-GC runs is possible using the Pyroprobe system. However, comparison of reproducibility as reported by different laboratories may not be justified, since individual groups have their own pyrolysis techniques. 

Global profile comparisons are also useful for comparing complex samples and were used to differentiate the pyrograms for different composite materials such as microorganisms. A simple global comparison is commonly obtained using a similarity index. There are various ways to calculate such an index. One procedure [42a], which is aimed to qualitatively compare two chromatograms A and B, uses the relation ... 

Juvet and co-workers [4] have used this technique for the preparation of fingerprint pyrograms of polymers. They claim that this technique yields considerably more simple and reproducible decomposition patterns than filament, furnace, and Curie point pyrolysers and claim that this is due to greater control of energy input and a more predictable manner in which the polymers decompose photolytically. Photolysis is carried out using a pure thin film of the polymer which is then irradiated using a medium-pressure mercury source. The photolysis products are swept onto a GC to produce a pattern characteristic of the polymer. The retention indexes of the photolysis products of some common polymers are given in Table 6.2. 

Thus, obtained mass spectrometric data for all the peaks on the pyrograms stored as the total ion chromatogram (TIC), and the selected mass spectra of the top 6 major peaks at most were compiled on this data book, together with the retention index (RI) data of the main peaks on the pyrograms. 

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