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Method for detection of extremely low concentration

Patent ·
OSTI ID:874199
 [1];  [2]
  1. Livermore, CA
  2. Bethal Island, CA
+ Show Author Affiliations
An ultratrace detector system for hand-held gas chromatography having high sensitivity, for example, to emissions generated during production of weapons, biological compounds, drugs, etc. The detector system is insensitive to water, air, helium, argon, oxygen, and CO.sub.2. The detector system is basically composed of a hand-held capillary gas chromatography (GC), an insulated heated redox-chamber, a detection chamber, and a vapor trap. For example, the detector system may use gas phase redox reactions and spectral absorption of mercury vapor. The gas chromatograph initially separates compounds that percolate through a bed of heated mercuric oxide (HgO) in a silica--or other metal--aerogel material which acts as an insulator. Compounds easily oxidized by HgO liberate atomic mercury that subsequently pass through a detection chamber which includes a detector cell, such as quartz, that is illuminated with a 254 nm ultra-violet (UV) mercury discharge lamp which generates the exact mercury absorption bands that are used to detect the liberated mercury atoms. Atomic mercury strongly absorbs 254 nm energy is therefore a specific signal for reducing compounds eluting from the capillary GC, whereafter the atomic mercury is trapped for example, in a silicon-aerogel trap.
Research Organization:
Lawrence Livermore National Laboratory (LLNL), Livermore, CA
DOE Contract Number:
W-7405-ENG-48
Assignee:
The Regents of the University of California (Oakland, CA)
Patent Number(s):
US 6338824
OSTI ID:
874199
Country of Publication:
United States
Language:
English

References (5)

Determination of reactive hydrocarbons by capillary gas chromatography with the reduction gas detector journal September 1994
Enzymatic Synthesis of Isoprene from Dimethylallyl Diphosphate in Aspen Leaf Extracts journal December 1991
Silica aerogel films prepared at ambient pressure by using surface derivatization to induce reversible drying shrinkage journal March 1995
Sub-parts per billion detection of isoprene using a reduction gas detector with a portable gas chromatograph journal November 1993
Airborne, Continuous Measurement of Carbon Monoxide in the Lower Troposphere journal January 1996

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Related Subjects

/422/73/436/
254
absorbs
absorption
air
argon
atomic
atoms
bands
basically
bed
biological
capillary
cell
chamber
chromatograph
chromatography
composed
compounds
concentration
cosub2
detect
detection
detector
discharge
drugs
easily
eluting
emissions
emissions generated
energy
etc
exact
example
extremely
gas
gc
generated
generates
hand-held
heated
helium
hgo
illuminated
initially
insensitive
insulated
insulator
lamp
liberate
liberated
material
mercuric
mercury
mercury vapor
metal--aerogel
method
nm
oxide
oxidized
oxygen
pass
percolate
phase
production
quartz
reactions
redox
redox-chamber
reducing
sensitivity
separates
signal
silica--or
silicon-aerogel
specific
spectral
strongly
subsequently
trap
trapped
ultra-violet
ultratrace
vapor
water
weapons
whereafter