Fraunhofer IGB has developed a measurement technique that allows volatile substances to be quantitatively measured simultaneously in gas phase and liquid phase in real time using a mass spectrometer. The sensitive measuring system is thus suitable for the automated monitoring and control of chemical reactions and biotechnological processes. This measurement technology is being adapted and further developed for a wide range of industrial processes.
Multi-inlet with membrane
At the heart of the patented measuring system is a modified inlet to the analyzer unit designed as a bypass, which - for the first time for mass spectrometry - also allows components from the liquid phase to be analyzed. A microporous membrane is attached to this inlet, through which - driven by the negative pressure on the permeate side - volatile substances evaporate from the liquid sample and pass through the membrane. The membrane is impermeable to polar, aqueous solutions. Its special spatial structure also makes it insensitive to clogging by solids.
Newly developed measuring sensor
In addition, a newly developed sensor enables the in-situ analysis of liquids, for example in fermenters during biotechnological production processes. In this case, the membrane, integrated in the sensor, is located directly inside the reactor to be monitored.
Automated control for real-time analysis
Which inlet is controlled by the sampler can be set by the user on the control unit. The Siemens programming developed by Fraunhofer IGB allows the user to switch between gas, liquid and in-situ analysis within seconds using appropriate valves, thus providing results in real time. In addition, the quadrupole mass spectrometer used is equipped with an auto-calibration feature, so that up to 30 components in the mixture of substances can be determined simultaneously - without prior separation.
The detection limits of the mass spectrometer are below 10 µg substance per litre and thus in the lower ppm range. Since the gases are sucked into the vacuum system of the detection unit via stainless steel pipes, distances of more than 10 meters to the sampling point are possible, making time-consuming pumping of the samples unnecessary. Depending on the length and diameter of the stainless steel capillaries, gases can be measured in real time in a vacuum of up to 1 mbar or at overpressure of up to 100 bar.
Fields of application
The real-time mass spectrometer is suitable for a wide range of applications in chemistry and biotechnology, pharmaceuticals and food production and is to be further developed for specific industries.