MONITORING PAH-EMISSIONS FROM COMBUSTION PROCESSES BY PHOTOELECTRIC CHARGING

Polycyclic aromatic hydrocarbons (PAH) are important in combustion pro cesses from two points of view: As precursors for soot formation and a s pollutants, if they are emitted. Usually PAHs are measured by GC-MS or HPLC analysis of filter extracts, which is a time and cost intensiv e procedure and does not allow on-line measurements. An alternative is photoelectric charging of particles by irradiation with ultravioletli ght. If an appropriate wavelength is chosen, the emission probability of electrons mainly depends on the amount of particle bound PAH(s). Th is allows a simple and fast monitoring of PAHs in emission and ambient air measurements. Here the application of this method to measure part icle bound PAHs in the exhaust of different combustion systems (oil bu rner, combustion engines) is discussed.