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60 t

60 t

Figure 16, Pyrolysis mass spectra of an oligosaccharide-oligopeptide mixture (maltopentaose and Phe-Asp-Met-Trp-Gly-Met-Tyr, 1:1 w/w ratio) showing the differences in fragmentation behaviour of both molecular components when different equilibrium temperatures are used.

Figure 16, Pyrolysis mass spectra of an oligosaccharide-oligopeptide mixture (maltopentaose and Phe-Asp-Met-Trp-Gly-Met-Tyr, 1:1 w/w ratio) showing the differences in fragmentation behaviour of both molecular components when different equilibrium temperatures are used.

In contrast to the relatively mild influence of changes in temperature profile, substitution of a ferromagnetic tube ("oven" pyrolysis) for the ferromagnetic wire produces pronounced changes in the pyrolysis mass spectra of most compounds as shown in Figure 17. As can be seen, oven pyrolysis of carbohydrate and proteinaceous materials produces a range of products due to secondary pyrolysis reactions, e.g. unsaturated and aromatic hydrocarbons. Moreover, spectra of chemically related materials produced by oven pyrolysis tend to show fewer characteristic differences than the corresponding filament spectra, whereas for obtaining reproducible oven-spectra smaller tolerances in pyrolysis and sample conditions exist. In conclusion, the use of ferromagnetic tubes is recommended only for relatively volatile samples which cannot be pyrolysed effectively by the filament technique, or in special cases where more rigorous thermal degradation is desired.

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