Real-Time Trace Detection of Elemental Mercury and its CompoundsEPA Grant Number: R825380
Title: Real-Time Trace Detection of Elemental Mercury and its Compounds
Investigators: Barat, Robert , Poulos, Arthur T.
Current Investigators: Barat, Robert
Institution: New Jersey Institute of Technology
EPA Project Officer: Hiscock, Michael
Project Period: November 25, 1996 through November 24, 1998
Project Amount: $199,121
RFA: Analytical and Monitoring Methods (1996) RFA Text | Recipients Lists
Research Category: Environmental Statistics , Water , Land and Waste Management , Air , Ecological Indicators/Assessment/Restoration
Owing to their high vapor pressure, airborne mercury and mercury compounds are emitted in significant quantity during fuel and waste combustion and in various industrial processes. The high toxicity of mercury and the ever-growing deployment of waste incinerators and power plants have prompted a demand (public and private) for accurate, real-time inventory and control of Hg emissions. Currently, there is no commercial device sensitive enough to detect Hg at all levels of interest, 1-1000 micrograms per cubic meter, in real-time, nor is there a technology for speciating various mercury compounds in air.
This research program will evaluate the capabilities and limitations of a novel hybrid instrument for measuring elemental and compounded mercury in air streams. The detection method uses Doppler-shifted Resonant Fluorescence (RF) for Hg and Photofragment Fluorescence (PFF) for Hg compounds, with test gas expanded in a supersonic jet. By incorporating an atomic vapor filter and measuring RF along the jet direction, extremely high sensitivity for elemental mercury is predicted, owing to the Doppler shifting of the fluorescence frequency away from the excitation frequency. The PFF spectrum for mercury compounds will also be produced at high sensitivity owing to the combination of reduced quenching, narrower line widths, and excitation with a recently developed high power excimer lamp. As a result, it is expected that fluorescing fragments will be readily distinguishable from interferences.
An experimental supersonic jet spectrometer will be built, and the detection capabilities will be evaluated on mercury-tainted air streams. The following performance indicators will be measured: limit of detection, range of linearity, relative accuracy, and response time. If excellent performance is found at laboratory scale, the concept can be readily developed into a relatively low cost instrument for field use.