|Assignment Status:||Assigned||Session Title:||ACS (American Chemical Society) Poster Session|
|Session Date||03/17/2019||Starting Time:||( Slot # 25 )|
Authors: Driscoll and Maclachlan
A method for the analysis of ppb levels of mercury using a photoionization detector (PID) with a 10.6 eV lamp was described several years ago. The ionization potential for Hg is 10.43 eV, so it responds to the PID. A new gold film in the preconcentrator was used to collect and concentrate the Hg vapor from the air.
The system is purged at 200 degrees C to remove any water vapor and/ or VOC’s from the gold film. This also improves the selectivity of the PID since all VOC’s which would respond are removed. Then the gold film is rapidly heated to 550 degrees C to remove the Hg.
We have decreased the volume of the preconcentrator by more than an order of magnitude and changed the heating method. Instead of a cartridge heater we are using an RF heater. We are now able to heat the low mass concentrator at ten times the speed. This gives us a much sharper peak and a much faster cool down time. We have improved the detection limit for Hg from about 10 ppb to < 1 ppb and with a reasonable sampling time, we can achieve < 1 ng/m3 which is a typical number for ambient air.