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Title: 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 (United States)
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)

Enzymatic Synthesis of Isoprene from Dimethylallyl Diphosphate in Aspen Leaf Extracts journal December 1991
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
Determination of reactive hydrocarbons by capillary gas chromatography with the reduction gas detector journal September 1994
Silica aerogel films prepared at ambient pressure by using surface derivatization to induce reversible drying shrinkage journal March 1995

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Related Subjects

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