Method for improving instrument response
- 7528 Oxford Cir., Dublin, Alameda County, CA 94568
- 2665 Calle Alegre, Pleasanton, Alameda County, CA 94566
- 5443 Celeste Ave., Livermore, Alameda County, CA 94550
- 5447 Theresa Way, Livermore, Alameda County, CA 94550
This invention pertains generally to a method for improving the accuracy of particle analysis under conditions of discrete particle loading and particularly to a method for improving signal-to-noise ratio and instrument response in laser spark spectroscopic analysis of particulate emissions. Under conditions of low particle density loading (particles/m.sup.3) resulting from low overall metal concentrations and/or large particle size uniform sampling can not be guaranteed. The present invention discloses a technique for separating laser sparks that arise from sample particles from those that do not; that is, a process for systematically "gating" the instrument response arising from "sampled" particles from those responses which do not, is dislosed as a solution to his problem. The disclosed approach is based on random sampling combined with a conditional analysis of each pulse. A threshold value is determined for the ratio of the intensity of a spectral line for a given element to a baseline region. If the threshold value is exceeded, the pulse is classified as a "hit" and that data is collected and an average spectrum is generated from an arithmetic average of "hits". The true metal concentration is determined from the averaged spectrum.
- Research Organization:
- Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
- DOE Contract Number:
- AC04-94AL85000
- Assignee:
- Hahn, David W. (7528 Oxford Cir., Dublin, Alameda County, CA 94568);Hencken, Kenneth R. (2665 Calle Alegre, Pleasanton, Alameda County, CA 94566);Johnsen, Howard A. (5443 Celeste Ave., Livermore, Alameda County, CA 94550);Flower, William L. (5447 Theresa Way, Livermore, Alameda County, CA 94550)
- Patent Number(s):
- US 6061641
- OSTI ID:
- 872993
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
improving
instrument
response
pertains
accuracy
particle
analysis
conditions
discrete
loading
particularly
signal-to-noise
ratio
laser
spark
spectroscopic
particulate
emissions
density
particles
resulting
overall
metal
concentrations
size
uniform
sampling
guaranteed
discloses
technique
separating
sparks
arise
sample
process
systematically
gating
arising
sampled
responses
dislosed
solution
disclosed
approach
based
random
combined
conditional
pulse
threshold
value
determined
intensity
spectral
line
element
baseline
region
exceeded
classified
hit
data
collected
average
spectrum
generated
arithmetic
hits
true
concentration
averaged
particulate emissions
laser spark
threshold value
spectral line
spectroscopic analysis
signal-to-noise ratio
particle size
noise ratio
metal concentrations
particle analysis
metal concentration
particulate emission
size uniform
/702/356/