Non-discriminating flash pyrolysis gas chromatography mass spectrometry.

摘要

Analytical pyrolysis is one of the many tools used for the study of artificial and natural organic polymers. However, analytical pyrolysis has both instrument-related and method-related shortcomings and limitations. The technique of non-discriminating flash pyrolysis-GC/MS was introduced to the analytical pyrolysis practice to overcome device-related shortcomings, in particular to avoid discrimination of high boiling pyrolyzates which occurs on transferring the analytes from the pyrolysis unit to the GC. This thesis describes the development of the non-discriminating flash pyrolysis system and presents some of its potential applications.; Non-discriminating flash pyrolysis is based on capacitive discharge heating of deactivated Silcosteel capillaries containing the samples. The design of the non-discriminating flash pyrolysis system has been continuously evolving since its introduction. The most recent modifications to the design include a septum-less injector interface, which eliminates the most significant bleed source at high injector and oven temperatures. A new power supply, which is capable of dual action pyrolysis and thermal desorption, results in more reproducible temperature for pyrolysis and post-heating. These modifications made the system more robust and user-friendly.; Non-discriminating flash pyrolysis system has been deployed for the analysis of a wide range of sample matrices including soil, airborne particulate matter, bacteria, sediments, etc.; This technique allows the detection of soil organic matter. While conventional pyrolysis cannot reveal high molecular weight analytes such as bio- and geohopanoids (hopanes) in soil samples reliably, the non-discriminating approach proved more promising. Likewise, non-discriminating flash thermochemolysis allows studying microbial communities in soil by virtue of determining fatty acid patterns.; The feasibility of non-discriminating flash pyrolysis-GC/MS as a fast technique for the analysis of ergorsterol as a biomarker of fungi has been investigated. The obtained pyrograms in this study confirmed the feasibility of this technique for the liberation and detection of ergosterol in various samples, including moldy bread (most likely Rhizopus nigri), indoor dust, and a plant leaf affected by powdery mildew. The presence of ergosterol, thus the presence of fungi in the pyrolyzed samples, could be confirmed with this technique.; The system has shown its usefulness in elucidating the macromolecular structure of sediments such as tertiary sandy sediments and Hamilton harbor sediments, due to the recovery of larger fragments from the macromolecular network within the sediment.; Non-discriminating pyrolysis system can be used for almost any kind of material, and only a small amount of sample is needed. No or minimal sample preparation is required, which makes the technique fast and environmentally friendly.