Development and optimization of a membrane-inlet-photoionization mass spectrometer for real-time analysis of (poly)aromatic and halogenated compounds in aquatic systems

由于(多)芳香族和卤代化合物的环境行为、高生物活性和毒性，快速、灵敏地分析它们具有重要的意义。海洋环境中此类化合物的浓度极低，使其难以检测和监测。因此，目前繁琐的浓缩技术(如吹扫捕集和萃取)被应用。在这方面，一种有希望的替代方法是共振增强多光子电离(REMPI)与飞行时间质谱学相结合。由于特殊的电离机制，REMPI提供了对(多)芳香族物种的选择性和灵敏的检测。在水生系统中使用REMPI的一个挑战是将溶解的分析物转移到气相。一种吉祥的方法构成了薄膜进水口的应用。对于膜进样质谱仪(MIMS)，分析物通过半透膜从液相有选择地输送到质谱仪的真空中，在此过程中失去了基质。优点是分析物在膜表面的浓缩和分析时间的显著减少。在拟议项目的框架内，将开发和优化用于实时分析海水中(多)芳香化合物和卤代化合物的REMPI-MIMS系统，以便在波罗的海巡航的一艘考察船上使用。除了膜进气口的规划和建造外，还提出了进气口与质谱仪的强健耦合的开发和表征。通过这样做，提高检测下限成为中心舞台。此外，还将研究与新分析系统性能有关的几个参数，如温度和盐度。该系统的验证将通过GC-MS测量进行交叉验证。

Fast and sensitive analysis of (poly)aromatic and halogenated compounds is of high importance due to their environmental behavior, high biological activity and toxicity. Very low concentrations of such compounds in marine environments make their detection and monitoring difficult. Therefore, currently laborious enrichment techniques (such as purge-and-trap and extraction) are applied. A promising alternative in this regard is resonance-enhanced multiphoton ionization (REMPI) coupled to time-of-flight mass spectrometry. As a result of the specific ionization scheme REMPI provides selective and sensitive detection of (poly)aromatic species. A challenge for the utilization of REMPI in aquatic systems is the transfer of dissolved analytes to the gas phase. An auspicious approach constitutes the application of membrane inlets. For membrane inlet mass spectrometry (MIMS) analytes are transported selectively from the liquid phase through a semipermeable membrane into the vacuum of the mass spectrometer, losing the matrix in the process. Advantages are enrichment of the analytes on the membrane surface and a considerable reduction of analysis time. In the framework of the proposed project a REMPI-MIMS system for real-time analysis of (poly)aromatic and halogenated compounds in sea water will be developed and optimized for employment on a research ship cruise in the Baltic Sea. Besides planning and construction of a membrane inlet the development and characterization of a robust coupling of the inlet to a mass spectrometer is put forward. By doing this, improvement of limits of detection takes center stage. Furthermore several parameters such as temperature and salinity will be investigated with respect to the performance of the new analytical system. Validation of the system will be cross-checked by GC-MS measurements.