Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS FOR EFFECTIVE COLLECTION OF EXPLOSIVE
AND NARCOTIC SAMPLES
Field of the Invention
The present invention relates to an apparatus and method for collecting
samples of explosive and narcotic substances from a cont~min~ted surface.
5 Back~round of the Invention
The direct detection of common explosives and narcotics is limited by
their very low vapour pressure. The task is further complicated in that often these
substances are bound by a host matrix such as for example, plastics for explosives and
sugars for narcotics. As with most substances, the vapour pressure of explosive and
10 narcotic substances is strongly temperature dependent. Heating a sample surface that
may contain traces of explosives or narcotics is a routine method of increasing the
vapour pressure of these substances prior to collecting vapours and introducing the
collected vapours to an analytical device.
However, heating alone is not sufficient to ensure adequate collection
15 of vapours from particulates of explosives or narcotics, and excessive heating is
unacceptable as it may cause damage to the surface being tested as well as to human
tissue.
Other sampling means that have been employed entail the use of
vacuum-based collectors of particulates of explosives or narcotics. These have proven
20 less than ideal for this task, as some particulates such as those of plastic-based
explosives, tend to adhere to surfaces. Accordingly, improvements in the collection
of vapours and particulates from explosive and narcotic substances are desired.
It is therefore an object of the present invention to provide a novel
apparatus and method for collecting particulates and vapours such as for example,
25 samples of explosive and narcotic substances from a surface.
Summary of the Invention
Broadly stated, the present invention provides an apparatus and method
for collecting particulates and vapours such as samples of explosive and narcotic
30 substances from a col-t~ ted surface. In one aspect, the present invention provides
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an apparatus for collecting particulates and vapours from a cont~min~ted surface
comprlsmg:
a manifold having at least one nozzle receiving gas from a supply and
directing at least one jet of gas onto a target area of said surface thereby to dislodge
5 particulates and vapours from said surface, said manifold also having an orifice
therein, one end of said orifice being adjacent said target area; and
a pump to draw gas and particulates and vapours dislodged from the
target area of said surface into said orifice thereby to collect said particulates and
vapours for analysis.
Preferably, the manifold includes a plurality of nozzles, each directing
a jet of gas onto the target area of the surface. The nozzles are oriented so that the jets
of gas transport dislodged particulates and vapours towards the orifice and are
arranged in a ring surrounding the orifice.
In one embodiment, the jets of gas create turbulence at the target area
15 of the surface. This is achieved by p~ ting the jets of gas or supplying gas to the
nozzles in succession.
In an alternative embodiment, the manifold further includes at least one
light source for directing optical energy onto the target area of the surface. Preferably,
the at least one light source includes an array of fiber optic conduits extending from
20 an external source of laser radiation. The fiber optic conduits are arranged on the
manifold so that beams of laser radiation em;~n:~ting from the fiber optics conduits
converge in the target area.
If desired, the flow of gas through the manifold which descends on the
cont~min~ted surface may be recycled by using a single pump to enhance the
25 concentration of particulates and vapours dislodged from the target area of the surface.
In addition, the jets of gas may be pre-heated to induce evaporation from particulates
dislodged from the cont~min~te~l surface.
According to one aspect of the present invention there is provided a
method for collecting particulates and vapours from a cont~min~ted surface
30 comprising the steps of:
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directing at least one jet of gas onto a target area of said surface
thereby to dislodge particulates and vapours from said surface; and
drawing gas and dislodged particulates and vapours from said target
area into an orifice having one end adjacent said target area thereby to collect5 particulates and vapours for analysis.
The present invention provides advantages in that particulates and
vapours can be collected from a surface for analysis effectively and without
contacting the surface.
10 Brief Dcr~. iylion of the Draw;n~
Embodiments of the present invention will now be described more
fully with reference to the accompanying drawings in which:
Figure 1 is a cross-section layout of an apparatus for collecting
particulates and vapours from a cont~min~ted surface in accordance with the present
15 invention; and
Figure 2 is a cross-section layout of an alternative embodiment of an
apparatus for collecting particulates and vapours from a coll~;..llill~ted surface in
accordance with the present invention.
20 Detailed Description of the Preferred Embodi.l.cnts
Referring now to Figure 1, an apparatus for collecting particulates and
vapours such as for example samples of explosive and narcotic substances from a
cont~min~ted surface is shown and is generally indicated to by reference numeral 10.
Apparatus 10 may be described as a "push-pull collection manifold" and is designed
25 to be placed over a cont~min~ted surface 12 to dislodge and draw particulates and
vapours therefrom without touching the surface. Apparatus 10 includes an annularmanifold 20 defining a central orifice 22. An intake 24 is provided in the manifold 20
and communicates with its hollow interior 26. An external motor-driven pump 28 is
connected to the intake 24 to force air 29 into the hollow interior 26 of the manifold.
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A circular ring of apertures defining nozzles 30 are provided in the
manifold 20. Each nozzle 30 communicates with the hollow interior 26. The nozzles
30 are oriented in a selected focused angle so that jets of air 32 descend from the
manifold 20 via the nozzles and contact a desired target area of the cont~min~ted
surface 12 to dislodge particulates and vapours therefrom.
A collection pump 34 pulls air 36 through the orifice 22 away from the
surface to collect dislodged particulates and vapours and direct them to a suitable
collection device or detection mech~ni~m (not shown).
If desired, the performance of the apparatus 10 may be enhanced using
10 one or more of the following techniques. The jets of air descending from the manifold
20 and collected by the collection pump 34 may be recycled by using a single pump to
enhance the concentration of particulates and vapours dislodged from the target area
of the surface 12. In this manner, air collected from the central orifice 22 is directed
to the intake 24. Also, air directed into the intake 24 by the external pump 28 may be
15 pre-heated to induce evaporation from particulates.
In addition, the external pump 28 may be pulsed to introduce
turbulence to the jets of air thereby augmenting agitation of the corlL~ ted surface
12. This can be achieved by p~ ting the supply of air to the manifold 20 or by
supplying air to the nozzles 30 in succession.
Although the appal~lus 10 has been described as having a single ring
of nozzles, those of skill in the art will appreciate that the manifold may include
several staggered rings of nozzles configured to discharge jets of air at different
pressures. Also, the external pump 28 can be replaced by a source of compressed air
supplying air under pLes~ule to the manifold 20.
Referring now to Figure 2, an alternative embodiment of an apparatus
for collecting particulates and vapours from a colll~ ted surface in accordance
with the present invention is shown. In this embodiment, like reference numerals will
be used to indicate like components of the previous embodiment with a " 100" added
for clarity. As can be seen, the manifold 220 is similar to that of the previous30 embodiment but further includes circular arrays of fiber optic conduits 200 therein
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extending from an external source of laser radiation 202. The arrays of fiber optic
conduits 200 are coupled to a single laser by means of a beam splitter/multiplexer
mech~ni.~m The fiber optic conduits 200 terminate at lens assemblies 204 arranged in
staggered rings within the manifold 120. The lens assemblies 204 are arranged so that
light beams 206 emerging from the lens assemblies 204 converge in the same focalarea as the jets of air 132.
It has been recently reported in the literature that selective desorption
of explosives and other non-volatile molecules is feasible using laser beams, for
example in the 226 to 337 nm W wavelength region. Alternatively, the laser
10 radiation may be in the infrared wavelength region. It has been demonstrated that as a
function of wave length, intensity and mode of operation, a laser beam can induce an
explosives sample to evaporate, and/or ionize and/or fragment.
It is estimated that by addition of the means for laser desorption, the
efficiency of sample collection of non-volatile particulates of explosives or narcotics
15 can be improved by about one order of magnitude (10 fold, quantitatively). For
example, ion mobility-based detection systems require ionization of the sample at the
input. Similarly, sample fragmentation is one of the early steps in systems that are
based on the electrochemical detection of NO or NO2 vapours, produced by the
fragmentation of particulates of explosive molecules.
Although particular embodiments of the present invention have been
described, those of skill in the art will appreciate that variations and modifications
may be made without departing from the spirit and scope thereof as defined by the
appended claims.
