Figure 24. Comparison of pyrolysis mass spectra of urban particulate (NBS, SRM 1648) obtained on different instrument, (a) Automated Py-MS apparatus, F.O.M. Institute, Amsterdam; (b) Extranuclear Labs, Py-MS instrument, Biomaterials Profiling Center, University of Utah. For differences in the low mass range, see Figure 23. Conditions: sample 10 yg; Tc 510°C; Ee] (a) 14 eV and (b) 11 eV.

have so far prevented the development of Curie-point Py-MS systems based on magnetic instruments for routine analytical applications. Fortunately, modern computer techniques allow some degree of compensation for transmissivity differences between quadrupoles. A simple way of correcting for transmissivity differences is to divide the spectra into sections of 14 mass units and to make comparisons between peak intensities within these sections only. Since such correction methods are far from perfect, however, the level of inter-laboratory reproducibi1ity achievable should not be expected to allow direct comparison of minute quantitative differences ir, fingerprints within the foreseeable future. Rather, the degree of inter-laboratory reproducibility obtainable should enable research workers to exchange data regarding the presence and interpretation of characteristic signals in different types of materials being analysed.

Chapter 6

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