Measuring and testing – Sampler – sample handling – etc. – Capture device
Reexamination Certificate
1999-09-24
2001-12-04
Noland, Thomas P. (Department: 2856)
Measuring and testing
Sampler, sample handling, etc.
Capture device
Reexamination Certificate
active
06324927
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for sampling cargo for chemical residues and, more particularly, to a method and apparatus for extracting particulates and vapors of chemical residues simultaneously from multiple cargo items.
Cargo, such as agricultural produce, general merchandise, and passengers' baggage, is routinely checked for chemical residues at transit points such as airports, seaports and border crossings generally. In the case of agricultural produce, the residues sought generally are pesticides and other health hazards. In the case of general merchandise and baggage, the residues sought include illicit substances such as drugs and explosives. This sampling can be tedious and time-consuming. For example, agricultural produce is inspected by selecting a representative sample, mechanically chopping the sample and chemically analyzing the sample. The familiar x-ray inspection of passengers' baggage at airports is performed one item at a time. The quality of this inspection depends on the alertness of the operator to spot suspicious items by their outline against complex backgrounds, as well as on equipment limitations. For a more intensive search based on chemical analysis, chemical samples are collected manually from the outside surfaces, or less commonly from the surfaces of the inside contents, of suspect baggage and parcels and transferred to an analytical instrument or to a reagent chemical test kit for identification. These manual sampling/analysis procedures can detect traces of pesticides on or within agricultural produce, as well as traces of illegal drugs and explosives deposited on the sampled surfaces in the course of handling drugs and explosives and hiding them in the baggage, parcels or cargo, but these procedures generally are slow and tedious, and therefore are restricted to a limited random sample of the inspected items.
A variety of automatic and semiautomatic systems have been proposed for collecting vapors and particulates from cargo items. These generally require that the items be loaded individually into a sampling chamber, although Cohen et al., in U.S. Pat. No. 5,162,652, teach the simultaneous loading of several items into several chambers, albeit still only one item per chamber. The invention of Cohen et al. and also the inventions of Jenkins, described in U.S. Pat. No. 3,941,357, and of Bradshaw et al., described in U.S. Pat. No. 3,998,101, are directed towards extracting vapor from the interior of sealed cargo by varying the pressure within the sampling chamber, typically by up to about 10% on either side of atmospheric pressure. Corrigan et al., in U.S. Pat. No. 5,345,809, and Reid et al., in U.S. Pat. No. 4,580,440, address the problem of sampling particulates on the surfaces of cargo items. Corrigan et al. teach a sampling chamber in which brushes remove particulates from the surfaces of cargo items. Reid et al. teach the agitation of a cargo transport container to suspend, in the air therein, particulates from the surfaces of the cargo items therein, followed by the sampling of the air with the suspended particulates. None of these prior art patents has addressed the problem of sampling particulates contained inside the cargo items.
There is thus a widely recognized need for, and it would be highly advantageous to have, an automatic contaminant sampling method that extracts samples automatically from several inspected items such as cargo items at once, and also extracts particulate contaminants from the interiors of the inspected items.
SUMMARY OF THE INVENTION
According to the present invention there is provided a method for sampling surfaces and interiors of a plurality of items for contaminant particulates and contaminant vapors, including the steps of: (a) sealing the items inside a chamber containing air at a certain pressure; (b) agitating the items, thereby releasing the particulates and the vapors from the surfaces and the interiors of the items into the air; and (c) inducing a flow of the air, together with the released particulates and vapors, towards a collection system.
According to the present invention there is provided a method for sampling surfaces and interiors of a plurality of items for contaminant particulates and contaminant vapors of chemical residues, including the steps of: (a) sealing the items inside a chamber; (b) introducing a gas into the chamber at a certain pressure; (c) agitating the items, thereby releasing the particulates and the vapors from the surfaces and the interiors of the items into the gas; and (d) inducing a flow of the gas, together with the released particles and vapors, towards a collection system.
According to the present invention there is provided an apparatus for sampling cargo for particulates and vapors of chemical residues, including: (a) a chamber, enclosing a gas at a certain pressure, wherein the cargo is placed for sampling; (b) a mechanism for agitating the cargo, thereby releasing the particulates and vapors into the gas; (c) a collection system for removing the particulates and vapors from the gas; and (d) a mechanism for inducing a flow of the gas, together with the particulates and vapors, towards the collection system.
According to the present invention, cargo items on a pallet are loaded en masse into an airtight chamber and subjected to physical agitation, including vibration, blasts of pressurized air into the chamber, jets of pressurized air directed at the cargo, and cycles of pressurization and depressurization, to release both vapors and particulates from both the interiors and the outer surfaces of the cargo items. The pressurized air may be heated before being directed at the cargo items. Solvent vapors may be introduced to the pressurized air, before it is directed at the cargo items. The adsorption of solvents on the surfaces of particulates often decreases the attractive forces between particulates adsorbed on surfaces and the surfaces on which they are adsorbed, making the particulates easier to dislodge. In addition, most solvents have a higher molecular mass than the constituents of air. Adding these solvents to the air increases the average momentum transfer in a collision between the air and the surfaces on which the particles are adsorbed. Typical solvents used for this purpose include carbon dioxide, acetone, dimethyl sulfoxide, propanol and organic amides. The object of this physical agitation is to knock loose aerosol-size contaminant particles on the exterior and interior surfaces of the items, and to encourage the vaporization of low vapor pressure chemical residues into the air in the chamber. In this manner, contaminant particulates from the outer surfaces of the items and from the interiors of the items are placed in suspension in the air in the chamber, and contaminant vapors from the outer surfaces of the items and from the interiors of the items are mixed with the air in the chamber. During the depressurization phases, air withdrawn from the chamber is passed through a collection system to collect the vapors and particulates. The collected vapors and particulates then are transferred to conventional analytic instruments for identification. If a targeted substance such as a pesticide residue, a trace of an explosive, or a trace of an illegal drug, is identified during this analysis, appropriate steps may be taken, including generating an audible and visible alarm. In addition, the items that were sampled collectively now may be sampled individually, using one or more of the prior art methods, to identify the item bearing the source of the targeted substance. In an airport setting, where the overwhelming majority of the baggage items do not contain contraband, the present invention may be used for an efficient mass preliminary screening of baggage items which is much faster than the prior art methods that deal with one baggage item at a time.
To keep the particulates in suspension during the depressurization phases, it has been found necessary to continue the blasts of pressuri
Buechler Samuel Solomon
Ornath Fredy
Friedman Mark M.
Noland Thomas P.
Ray Buechler Holdings (1995) Ltd.
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