Ultrasensitive, Instantaneous Detection of
Polycyclic Aromatic Hydrocarbons (PAH)

Here is a recent publication by our group on this subject.

New regulations imposed on industry to minimize their emissions of hazardous air pollutants will require the continuous monitoring of trace toxic by-products such as PAHs. Presently, trace measurements ar e made by pre-concentrating them over adsorbates, followed up by extensive liquid extraction processes to recover these pollutants, reconcentration and finally GC/MS analysis. The whole process is very tedious and subject to s ignificant errors because of the presence of numerous sample transfer steps. In addition, the measurements using GC/MS do not provide an accurate representation of second-to-second variations of process emissions, such as transient puffs, and as such cannot be used for the real-time monitoring and control of emissions processes. In order to solve this significant practical problem, we are developing a Photoionization Time-of-Flight Mass Spectrometer (TOFMS). This a highly compact and transport able unit with a proven detection sensitivity of about 50 parts per trillion (ppt) for naphthalene in real time, i.e. within milliseconds.

The schematic diagram and applications of a Photoionization Time-of-Flight Mass Spectrometer (TOFMS) for the detection of PAHs produced in combustion systems.

The TOFMS developed has recently been shown to provide a real time detection sensitivity of about 50 parts per trillion (ppt) for napththalene in argon without any pre-concentration steps and shows a linear response to concentration over 6 orders of magnitude.

Typical response of Naphthalene at 248 nm in a Photoionization TOFMS.

Currently, a large number of PAHs have been detected up to and including benzo(a)pyrene (252 Daltons) within 45 microseconds. Therefore, this instrument can be used to continuously monitor the effluents of industrial processes that are believed to emit PAHs into the atmosphere and can be coupled to controllers in order to change operating conditions to minimize or eliminate the emission of these PAHs in real time. Since PAHs emitted at the parts per trillion level can be detected, the TOFMS has the ability to set the standard in the pollution control sector of industry, thus ensuring that industries are operating at the most environmentally friendly conditions possible.

Here is a recent publication by our group on this subject.

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