Photo ionisation-time of flight mass spectrometry (PI-TOFMS) has been established for on-line analysis of complex gas mixtures. Cigarette smoke, e-cigarette vapour and the vapour of tobacco heating products provide good examples for such complex gas mixtures. Many toxicants, such as butadiene, acetaldehyde, naphthalene, phenol or polycyclic aromatic hydrocarbons (PAH), can be detected with single puff-resolution in the smoke or vapour of products.

Vacuum PI-MS can be differentiated into SPI (single-photon-ionisation), ionising a wide range of organic molecules, and REMPI (resonance-enhanced-multi-photon-ionisation), focusing primarily on aromatic structures. Especially the more sophisticated complementary use of SPI and REMPI can provide access to profound information allowing mechanistic understanding of processes.

Soft photoionisation can be applied in various research fields and applications dealing with complex gas mixtures that need to be observed in real time. The high time resolution especially enables the investigation of fast and dynamic processes. Considering the variety of cigarettes and innovative aerosol products, such as e-cigarettes and tobacco heating products (THP), photoionisation enables a puff resolved investigation of released compounds from nicotine to harmful or potentially harmful compounds (HPHCs). In addition to time resolved detection, spatial occurrence of smoke constituents in the cigarette can be investigated. Based upon spatiotemporal data, chemical heat maps can be generated, which allow the understanding of the formation and degradation processes even inside a cigarette.

Other products, e.g. tetrahydrocannabinol (THC) containing smoking products such as joints, have been investigated on a puff-by-puff resolved basis.

In summary, the release of the desired active compounds (e.g. nicotine or ∆9-THC) and undesirable HPHCs is dependent on a broad set of parameters, such as puff regime, environmental conditions and physical product design features. The puff-by-puff resolved release profiles derived by on-line photo-ionisation MS enables a reliable understanding of mechanistic processes and reaction pathways.