The Clean Air Act of 1990 has raised the concern over trace concentrations of metals in flue gas from electrical generation plants, municipal waste incinerators, and heavy industrial plants. Monitoring will be required to determine the environmental impact and offers an opportunity to empirically minimize it. In flue gas, metals are found in both the vapor state and condensed on fly ash. For species other than mercury, the metals are predominantly on fly ash particles. This Phase I project will develop an ultrasensitive continuous monitor for trace metals such as Cd, Cr, As, Se, and Pb captured on fly ash particles. Detection limits below 1 µg/m3 for gaseous phase mercury have been attained by emission spectroscopy using EEI's innovative microwave plasma source. Similar sensitivities should be attainable for other metals in the vapor phase with this detector. Detection of solid fly ash particles at levels equivalent to approximately 1 µg/m3 will be achieved by using a filter-heating element assembly in the gas flow close to the plasma. When heated for short times to temperatures above 1,000 K, an elevated concentration of metals trapped in the fly ash will be released into the plasma discharge for spectroscopic detection. A successful Phase I program will provide a new continuous monitor capable of measuring absolute concentrations of metals in both the vapor phase and on the fly ash in industrial flue gas and air streams with a time resolution of approximately 30 seconds and concentrations of approximately 1 µg/m
