Grantee Research Project Results

Final Report: Multimetals Emission Monitoring System Based on Spark-Induced Breakdown Spectroscopy

EPA Contract Number: EPD04018
Title: Multimetals Emission Monitoring System Based on Spark-Induced Breakdown Spectroscopy
Investigators: Hunter, Amy J.R.
Small Business: Physical Sciences Inc.
EPA Contact: Richards, April
Phase: I
Project Period: March 1, 2004 through August 31, 2004
RFA: Small Business Innovation Research (SBIR) - Phase I (2004) RFA Text |  Recipients Lists
Research Category: SBIR - Air Pollution , Small Business Innovation Research (SBIR) , Air Quality and Air Toxics

Description:

Spark-induced breakdown spectroscopy (SIBS) is a method developed at Physical Sciences, Inc., to monitor the elemental composition of airborne particles and solids through vaporization, atomization, and excitation of these elements with an electrically generated spark. This system has been successfully used to monitor lead (Pb) and chromium (Cr) in airborne particulate material in the past. In this research project, it was applied to the measurement of arsenic (As) and selenium (Se).

These elements are listed in the federal register as hazardous air pollutants (HAPs), and there currently is no real-time method for their measurement. This represented an interesting challenge in terms of the characteristics of the atomic emission features from these two elements. The brightest emission features are in the deep ultraviolet (UV) (193.7 nm [As] and 196 nm [Se]), a region that Physical Sciences, Inc., has never explored before.

The goal of this research project was to establish proof-of-principle that these two important elements could be measured in aerosol form by spark excitation and subsequent detection in the UV region. A probe that would support the spark in situ in an exhaust duct was designed and mated with a small, inexpensive detection system, and the spectra of AS, Se, and Pb were acquired. The Pb spectra were collected to enable comparison between the current monitoring configuration and prior, more expensive detection methods.

Summary/Accomplishments (Outputs/Outcomes):

All five tasks from the statement of work were successfully completed and the technical objectives were achieved. In Phase I, Physical Sciences, Inc., designed, built, and tested a novel toxic metal aerosol sensor that had the following characteristics:

• Operation from the deep UV (180 nm) to visible wavelengths (~500 nm).


• Design of a probe to deliver the spark in situ to particulate material entrained in gaseous emissions in an exhaust duct.


• Incorporation of a miniature CCD detector to the probe.


• Detection of As and Se aerosols.


• Attracted serious interest from Ocean Optics, Inc., a highly successful optical sensor company, to include this SIBS system as a potential addition to their product line.


• Used the Phase I results to design a Phase II instrument with enhanced sensitivity that will make the system generally applicable to U.S. Environmental Protection Agency needs.

Conclusions:

In the limited resources of Phase I, Physical Sciences, Inc., was not able to optimize the sensitivity of the detection system, but concepts that are believed to allow for the detection of both As and Se at ppb levels were developed. These concepts will allow for the detection of numerous other Resource Conservation and Recovery Act metals simultaneously. These concepts will be examined in Phase II, the optimal one selected, and a breadboard instrument calibrated for six metallic HAPs.

Supplemental Keywords:

spark-induced breakdown spectroscopy, SIBS, hazardous air pollutant, HAP, arsenic, As, selenium, Se, ultraviolet, UV, aerosol, exhaust duct, SBIR,, RFA, Ecosystem Protection/Environmental Exposure & Risk, Scientific Discipline, Air, particulate matter, Air Quality, Environmental Chemistry, Engineering, Chemistry, & Physics, Analytical Chemistry, Monitoring/Modeling, Atmospheric Sciences, Environmental Monitoring, aerosol particles, chemical characteristics, gas chromatography, particle size, particle sampler, air sampling, emissions, atmospheric chemistry, human exposure, chemical detection techniques, monitoring, HAPS, air quality model, particulate matter mass, ambient emissions, metal speciation, aerosol analyzers, air quality models, arsenic speciation, spark-induced breakdown spectroscopy, human health effects, multimetal emissions

SBIR Phase II:

Multimetals Monitoring System Based Upon Spark-Induced Breakdown Spectroscopy