When analysing aerosols, scientists are increasingly turning to online measuring devices to investigate the chemical composition of organic aerosols. For example, aerosol- or single particle mass spectrometers for characterising the particulate matter and online mass spectrometers with direct gas inlet and soft ionisation for direct probing of the gas phase are widely used here. The sample is taken directly at the point of emission or immission and may only need to be diluted or pre-concentrated to obtain real-time data. However, these systems are not very selective and the specification of the organic compounds is based on assumptions and only covers a few individual compounds in complex matrices. The output is often only some parameters or bulk properties. A more detailed specification of the organic aerosol is usually carried out by taking sample material of the gas and particle phases on suitable material. The analysis is then typically carried out both temporally and spatially separated, and also includes complex sample preparation steps to subsequently analyse them using chromatographic methods. Changes to the matrix due to storage or manual handling cannot be ruled out. In addition, the use of different measuring systems for analysing the gas and particle phase leads to limited comparability.
In our poster, we want to introduce a hybrid system for the analysis of the particulate matter as well as gas phase simultaneous at the point of emission or immission.
Particulate matter is collected using a filter-based sampling unit compatible with standard 25 mm planar filter material. Automatic exchange and conditioning of filter units for each sample prevents artefacts common with fixed sampling units. The chemically inert casing is reusable, while loaded filter units are either automatically transferred to a unique desorption unit for at-line analysis, or stored for later offline analysis. Concurrently, the gas phase is sampled from the same sample line, applying VOC absorber tubes loaded with conventional trapping material. The desorption and sampling unit for the gas phase, which can also be triggered automatically, could be individually adjusted from the PM sampling.
The sampling times can be flexibly adapted to the measurement cycle, which is made possible by intermediate storage of the samples. In addition, both desorption units facilitate interleaved processing of collected samples, allowing for seamless analysis. Furthermore, the system design accommodates mounting on standard GC injection ports, offering versatility in detection systems for both targeted analysis and fingerprinting applying mass spectrometric and spectroscopic detectors. Conventional gas chromatographs are used to analyse the thermally desorbed sample material, which allows the analysis to be adapted to the target compounds and matrix.
The system also allows an integration of third-party devices for a further and complementaryphysical and chemical characterization to obtain a comprehensive picture of the collected sample material.
We will present the application of the system for direct emission derived for combustion engines operating under different conditions as part of a tightly timed measurement campaign. As a second example, we show data on autonomic sampling and analysis of environmental aerosols operating in remote mode.
This Project is supported by the Federal Ministry for Economic Affairs and Climate Action (BMWK) on the basis of a decision by the German Bundestag (grant ID: KK5037301JO0) and by dtec.bw-Digitalization and Technology Research Center of the Bundeswehr (projects “LUKAS” and “MORE”). Dtec.bw is funded by the European Union – NextGenerationEU.
«When analysing aerosols, scientists are increasingly turning to online measuring devices to investigate the chemical composition of organic aerosols. For example, aerosol- or single particle mass spectrometers for characterising the particulate matter and online mass spectrometers with direct gas inlet and soft ionisation for direct probing of the gas phase are widely used here. The sample is taken directly at the point of emission or immission and may only need to be diluted or pre-concentrated...
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