Factors influencing long-term reproducibility in Curie-point Py-MS have been studied in detail by Meuzelaar (ref. 100) and Windig et al. (ref. 101). Table 2 lists possible factors influencing various steps of the analytical procedure in Py-MS. A detailed examination of factors involved in sample preparation and pyrolysis steps showed that some deliberate changes in experimental conditions caused changes in average peak height (40 most intense peaks) of over 20%, as listed in Table 3. In practice, however, the experimental parameters involved are controlled much more closely. Therefore, the estimated combined contribution of these factors to long-term variations observed in the spectra is less than 3 - 4%. This leads to the conclusion that the major causes of imperfect long-term reproducibility must be sought in factors influencing sample transfer and/or mass spectrometry analysis rather than in factors influencing sample preparation and pyrolysis.
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