Feasibility Study of Using Short Wave Infrared Cavity Ringdown Spectroscopy (SWIR-CRDS) for Biological Agent Detection
This project focused on determining the feasibility of using short wave infrared (SWIR) cavity ring down spectroscopy (CRDS) as a means for real-time detection of biological aerosols. The first part of the project involved identifying biological agent signatures that could be detected with SWIR CRDS. After an exhaustive search of the open literature it was determined that whole biological spores and/or cells would not be good candidates for direct SWIR CRDS probing because they have no unique SWIR signatures. It was postulated that while whole cells or spores are not good candidates for SWIR CRDS detection, their pyrolysis break-down products might be. A literature search was then conducted to find biological pyrolysis products with low molecular weights and high symmetry since these species most likely would have overtone and combination vibrational bands that can be detected in the SWIR. It was determined that pyrrole, pyridine and picolinamide were good candidates for evaluation. These molecules are formed when proteins and porphyrins, proteins and dipicolinic acid, and dipicolinic acid are pyrolyzed, respectively. The second part of the project involved measuring quantitative SWIR spectra of pyrrole, pyridine and picolinamide in PNNL’s FTIR Spectroscopy Laboratory. Spectral information about these molecules, in the vapor phase is sparse – there were only a few prior studies that measured line positions and no information on absorption cross sections. Absorption cross sections are needed in order to estimate the SWIR CRDS detection sensitivity, and line position determines what type of laser will be needed for the sensor. The results of the spectroscopy studies allowed us to estimate the SWIR CRDS detection sensitivity for pyrrole to be 3 x 1012 molec cm-3 or 0.1 ppmv, and for pyridine it was 1.5 x 1015 molec cm-3 or 0.6 ppmv. These detection sensitivity limits are close what we have measured for ammonia. Given these detection limits we then estimated the amount of biological material that would have to be collected for analysis in a sensor that combined pyrolysis with SWIR CRDS. Using conservative estimates of pyrolysis yields and precursor species concentration we determined that it would be necessary to collect and pyrolyze biological aerosol samples in the 10’s of mg. This is a large amount and is far larger than required for current sensors. It is therefore concluded that while possible, the large amounts of material required preclude using SWIR CRDS for detecting biological agents at this time.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 949941
- Report Number(s):
- PNNL-16595; 17995; NN2001000; TRN: US200909%%562
- Country of Publication:
- United States
- Language:
- English
Similar Records
Chemical Sensing Using Infrared Cavity Enhanced Spectroscopy: Short Wave Infrared Cavity Ring Down Spectroscopy (SWIR CRDS) Sensor
Thermal transformations of nitrogen and sulfur forms in peat related to coalification
Related Subjects
ABSORPTION
AEROSOLS
AMMONIA
BIOLOGICAL MATERIALS
CROSS SECTIONS
DETECTION
LASERS
MOLECULAR WEIGHT
PORPHYRINS
PRECURSOR
PROTEINS
PYRIDINE
PYROLYSIS
PYROLYSIS PRODUCTS
PYRROLES
SENSITIVITY
SPECTRA
SPECTROSCOPY
SPORES
SYMMETRY
VIBRATIONAL STATES
Cavity Ringdown Spectroscopy
biological agent detection
Environmental Molecular Sciences Laboratory