Entwicklung und Bewertung von Probenfiltern zur Messung von RDX aus der Gasphase mittels DMA-MS

Kurzfassung

The aim of this work is to develop and characterize metal mesh filters for use as sample filters for thermodesorption using DMA-MS. These were coated with TiO₂ using TTIP or with Tenax TA via a dip-coating process, while Tenax-based filters from the manu facturer MION were also used as a reference. The coatings were analyzed and char acterized using digital microscopy, Raman spectroscopy, and scanning electron mi croscopy. At the same time, the adsorption capacity and resulting performance were evaluated using a test gas line also constructed in this work and RDX using DMA-MS. The TiO₂ layers produced using TTIP show a pronounced dependence on the dip coat ing process. Raman measurements confirmed the formation of TiO₂, both in the ana tase and rutile phases, depending on the drying conditions. The DMA-MS measure ments showed very low peak areas for RDX, regardless of the phases produced, and were below the calibration of the RDX method. This indicates that, despite the probable presence of adsorption, the TiO₂ coatings in the present design do not allow efficient desorption and the resulting detection of RDX. In contrast, the Tenax-TA coatings, which were also produced using a dip-coating pro cess, formed open-pored, net-like structures with a large active surface area. These filters showed high and well-reproducible DMA-MS signals for RDX and achieved per formance comparable to that of commercial MION filters. In addition, the uncoated metal meshes also showed unexpectedly high adsorption signals, indicating strong non-specific interactions between RDX and the metallic surface. The FRANC gas test line enabled reproducible and controlled loading of filters with RDX from the gas phase, whereby the loading quantity could be reliably varied over the draw time. Long-term measurements confirmed stable peak areas and reproduci ble DMA-MS detection, allowing material-dependent adsorption and desorption prop erties to be identified as the cause of the observed differences.