Measuring and testing – Sampler – sample handling – etc. – With heating or cooling
Reexamination Certificate
1998-06-12
2001-02-27
Raevis, Robert (Department: 2856)
Measuring and testing
Sampler, sample handling, etc.
With heating or cooling
Reexamination Certificate
active
06192766
ABSTRACT:
The present invention relates to an apparatus, a system and a method for the detection of an analyte in air. The invention is particularly concerned with the detection of dangerous chemicals such as explosives, mines, bombs, war gases and narcotics.
BACKGROUND
It is difficult to selectively detect small amounts of a gaseous analyte in air, and it is particularly important to do so when the location of dangerous chemicals is to be determined.
For example, since World War II, mine detection has been mostly carried out with the help of metal seekers that detect small amounts of metal contained in most mines. As a result of the development of anti-personal mines with less and less metal, the sensitivity of a metal seeker has been enhanced to give alarm for less than one gram of metal. However, at this sensitivity level metal fragments in the ground will block its use in most mined terrain by giving a false alarm.
Another method for mine detection, and narcotics detection, which has been successfully applied, has been the use of trained dogs. But even the best dog can only work for short periods with full attention and with long rest periods in between. Well trained dogs are also very expensive.
It would be desirable to have an apparatus, a system and a method for the selective detection of small amounts of an analyte in air for many applications, e.g. in the process industry for the detection of specific contamination or leakage, in the airport safety control, customs and police work for the detection of narcotics and bombs, and in clearing the terrain of mines and bombs after a war situation.
DESCRIPTION OF THE INVENTION
The present invention provides an apparatus, a system and a method for the selective detection of an analyte in a sample of air. The sample of air is collected at a suspected location. The possible specific analyte is enriched from the air sample in accordance with the present invention, and finally the specific analyte of interest is analyzed from a small amount of liquid.
One aspect of the invention is concerned with an apparatus for the detection of an analyte in air comprising
an air sampling system (
1
) for collecting an air sample comprising a mouthpiece (
10
) and a fan,
means for transport of the air through a first enrichment state (
11
) for enrichment of the analyte comprising a thermally regulated adsorption/desorption filter creating a non-laminar gas flow for adsorption of the analyte on the filter surfaces, encased in a housing having a gas inlet and a gas outlet connected to valves, and a heat source for heating the filter to a temperature high enough to evaporate the analyte but low enough to avoid decomposition of the analyte,
means for transport of the desorbed analyte from the filter to a second enrichment stage for the further enrichment of the gaseous analyte comprising a cold trap (
32
) for condensing the analyte, means for extraction of the condensed material with a solvent, and means for collecting the solution enriched in analyte from the cold trap, and
means for transport of the collected liquid sample to an analytical detection system for the detection of the analyte.
In a preferred embodiment of this aspect of the invention, the valves are substituted for a revolver, the first enrichment stage is reconditioned by cooling gas, and the second enrichment stage is connected to a revolver and reconditioned by washing the cold trap with a solvent.
Another aspect of the invention is concerned with an adsorption/desorption filter creating a non-laminar gas flow, which comprises a gas inlet and a gas outlet connected to a housing (
20
) in which a winding (
21
) of a resistance wire, such as a copper wire, coated with an active (insulating) material having affinity for an analyte to be tested, such as Teflon®, is encased, and two connector bands (
22
) attached to the ends of the wire for electric heating of the wire to a temperature that provides a temperature on the surface of the active material at which the analyte is desorbed without decomposition.
A further aspect of the invention is concerned with a system for the detection of an analyte in air comprising
an air sampling system comprising a mouthpiece and a fan,
a first enrichment stage for enrichment of the analyte comprising a thermally regulated adsorption/desorption filter creating a non-laminar gas flow comprising a housing having a gas inlet and a gas outlet connected to valves, and
a heat source for heating the filter to a temperature high enough to evaporate the analyte but low enough to avoid decomposition of the analyte,
a second enrichment stage for the further enrichment of the analyte comprising a cold trap for condensing the analyte, extraction of the condensed material with a solvent, and collecting the solution enriched in analyte from the cold trap, and
an analytical detection system for the detection of the analyte from a liquid sample.
In a preferred embodiment of this aspect of the invention, the valves are substituted for a revolver, the first enrichment stage is reconditioned by cooling gas, and the second enrichment stage is connected to a revolver and reconditioned by washing the cold trap with a solvent.
Yet another aspect of the invention is concerned with a method of detecting an analyte in air comprising
sampling of air with an air sampling system comprising a mouthpiece and a fan,
passing the air to a first enrichment stage where the analyte is adsorbed on the surfaces of a thermally regulated adsorption/desorption filter creating a non-laminar gas flow,
heating the filter surfaces to a temperature high enough to evaporate the analyte but low enough to avoid decomposition of the analyte,
flushing the filter with a small amount of an inert gas, such as nitrogen or air,
passing the vapor from the first enrichment stage to a second enrichment stage for the further enrichment of the analyte by condensation in a cold trap,
flushing the cold trap with a small amount of solvent to dissolve the condensed material,
collecting the small amount of solution containing the analyte in an container, and
analyzing the presence of analyte in the container with the aid of an analytical detection system for the detection of the analyte in liquid sample.
In a preferred embodiment the analyte is a gaseous component of explosives or mines, such as TNT (2,4,6-trinitrotoluene), RDX (1,3,5-trinitro-1,3,5-triazacyclohexane) or PETN (pentaerythritoltetranitrate).
The invention is also concerned with the use of the apparatus and system, respectively, each according to the invention, for the detection of a gaseous component of explosives or mines, e.g. TNT (2,4,6-trinitrotoluene), RDX (1,3,5-trinitro-1,3,5-triazacyclohexane) or PETN (pentaerythritoltetranitrate), and use of the adsorption/desorption filter according to the invention in an apparatus, system and method for the detection of an analyte in air.
The invention will now be illustrated with the air of the following description of specific embodiments, related drawings and examples. However, the invention should not be considered to be limited to such exemplification.
An apparatus, a system and a method of the invention preferably comprises the following elements
1) An Air Sampling System Comprising
mouth piece
dust filter (optional)
hygrometer (optional)
fan (or external pump)
injection valve (preferred embodiment)
2) A First Enrichment Stage Comprising
adsorption/desorption filter of active (insulating) (e.g. hydrophobic) material
valves (revolver)
heater
filter reconditioning
3) A Second Enrichment Stage Comprising
cold trap
solution
pump (optionally manual injection)
washing (reconditioning of cold trap)
4) One or more analytical detection system(s), such as a) gas chromatograph or b) biosensor(s) (each) comprising
flow cell
quartz crystal
surface antibody coating, the antibody being specific for an binding to
the specific analyte of interest
5) Optional Signal Processing Comprising, in the Case of 4) b),
reference oscillator
CPU
serial communication link
6) Optional Man Machine Interface Comprising
acoustic alarm
presenta
Alm Arne
Andersson Claes
Arnell Johan
Gårdhagen Peter
Jansson Åke
Bacon & Thomas
Biosensor Applications Sweden AB (publ)
Raevis Robert
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