Hyphenation of thermogravimetry and soft single photon ionization–ion trap mass spectrometry (TG–SPI–ITMS) for evolved gas analysis

Abstract

Thermal processes are part of many industrial treatments; therefore, it is of great interest to gain more insight of these processes. Evolved gas analysis (EGA) is the most straightforward way to make chemical reactions in thermal processes accessible for on-line investigations. The sample matrix of evolved off gas e.g., from coffee roasting is a permanently changing and complex mixture of a multitude of substances that have to be analyzed simultaneously for real on-line investigations without any sample trapping or separation device. Therefore, a measurement system as an ion trap mass spectrometer (ITMS) with soft ionization is required with its tandem mass spectrometry capability to provide distinct substance identification unperturbed by the remaining matrix. The presented novel system setup is based on a thermogravimetric device (TG) to simulate the thermal treatment as in industrial processes combined with an ITMS with soft single photon ionization (SPI) to achieve the required substance information. Hence it is possible to gain single mass spectrometric information of expected substances for process control. More comprehensive than that are the two-dimensional MS data which are required for research and process development purposes though. The conducted analyses show that this novel setup is able to provide distinct substance identification in evolved gas of roast and ground coffee powder. To our knowledge, this is the first TG–SPI–ITMS setup with successful application in verifying the identity of different mass traces within a single run.