The heart of the requested infrastructure (PTR-Qi-TOF-MS) consist of a high-resolution (mass resolution (10000 m/Dm Full Width at Half Maximum), real -time, ultra-sensitive online trace-gas (VOCs) analyzer, based on proton transfer reaction mass spectrometry employing a quadrupole ion guide prior to a time-of-flight mass spectrometer.The new design of PTR-Qi-TOF instrument offers improved sensitivity (limits of detection: <pptv).Three integrated additional features are necessary: (a) the ionisation using Selective Reagent Ionization (SRI and SRI+) with NO+, O2+, H3O+ and Kr+ precursor ions to measure a multitude of VOC compounds (b) a temperature controlled multiport valve (c) a fast NDIR CO2 sensor. The near real time measurement of isomers is ascertained by a Fast-GC installed prior to the PTR-Qi-TOF and is essential given the complexity of the VOC mixtures to be analyzed. For calibration of the instrument an advanced Liquid calibration unit (LCU-a) must be used.