Figure 8. Curie-point pyrolysis mass spectrum of natural rubber (cis-1,4-polyiso-prene). Note prominent ion signals at m/z 68 and 136, apparently representing the molecular ions of monomeric and dimeric units, (f) designates EI fragment ions. Conditions:sample 10 pg; E , 14 eV (see Atlas).
preferable to use rapid filament pyrolysis rather than direct probe pyrolysis techniques, in order to avoid unnecessary secondary pyrolysis reactions resulting in the production of multiple unsaturated or even aromatic pyrolysis products.
Interesting results have also been obtained with phospholipids owing to the presence of highly characteristic moieties such as choline. Weijman (ref. 70) reported the occurrence of a characteristic ion series at m/z 59, 71 and 89, presumed to be trimethyl amine, vinyldimethylamine and N,N-dimethylaminoethanol, respectively (see Figure 9), in the pyrolysate of fungal phospholipids. The abovementioned identity of the m/z 59 fragment molecule in the pyrolysate of lecithin (phosphatidy-choline) was proved by Louter et at. (ref. 80) using Py-MS/MS. A curious phenomenon is regularly observed in the pyrolysis of phospholipid preparations, namely the methylation of chloride ions resulting in methylchloride (m/z 50, 52 in Figure 9), (see also Section 2.3.).
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