Highly Resolved Online Organic-Chemical Speciation of Evolved Gases from Thermal Analysis Devices by Cryogenically Modulated Fast Gas Chromatography Coupled to Single Photon Ionization Mass Spectrometry

摘要

Multi-dimensional analysis (MDA) in analytical chemistrynis often applied to improve the selectivity of an analyticalndevice and, therefore, to achieve a better overview of ansample composition. Recently, the hyphenation of thermogravimetrynwith single photo ionization mass spectrometryn(TG-SPIMS) using an electron beam pumpednexcimer lamp (EBEL) for VUV radiation was applied. Thenconcept of MDA has been realized by upgrading the TGSPIMSnsystem with a quasi comprehensive chromatographicnseparation step before the soft ionization (TGGCxSPIMS).nThe system was characterized by the thermalnanalysis of diesel fuel, which has often been investigatednby the GCxGC-community and is therefore a well-knownnsample material in MDA. Data from this measurement arenused to explain the three-dimensional data structure andnthe advantages of the online TG-GCxSPIMS as comparednto TG-SPIMS. Subsequently, the thermal decompositionnbehavior of a polymer, acrylonitrile-butadiene-styrenen(ABS), is investigated. TG-GCxSPIMS provides a twodimensionalnanalysis of the evolved gaseous products. TGnrelevant data are obtained as well as an improved resolutionnpower to separate isobaric molecular structuresnwithout losing any fraction of the samples, as is often thencase in heart cutting approaches. Additionally, this solutionnis not associated with any extension of the measurementntime. The assignment of the substance pattern tondistinct species is improved as compared to solely usingnmass spectrometry without a preceding separation step.nFurthermore, hitherto undetected compounds have beennfound in the evolved gases from the thermal degradationnof ABS. Finally, a first estimation of the limit of detectionnhas been carried out. This results in a significant decreasenof the LOD in case of TG-GCxSPIMS (500 ppt for toluene)nas compared to 30 ppb, which could be reached withnTG-SPIMS.