WO2013184098A1

WO2013184098A1 - Verification token

Info

Publication number: WO2013184098A1
Application number: PCT/US2012/040854
Authority: WO
Inventors: Tim Burton; Abiy ESHETU
Original assignee: Dsa Detection Llc
Priority date: 2012-06-05
Filing date: 2012-06-05
Publication date: 2013-12-12

Abstract

Embodiments of the present invention are directed to verification tokens and methods of formation and use of verification tokens for verifying calibration of equipment for the analysis of trace samples from an object of interest for the presence of one or more substances of interest.

Description

VERIFICATION TOKEN

BACKGROUND OF INVENTION

Aspects and embodiments of the present invention are related to apparatus and methods for verification tokens and for verifying the calibration of apparatus for the collection and analysis of trace samples of material for testing for the presence of contraband such as illicit drugs and/or explosives.

SUMMARY OF INVENTION

Aspects and embodiments of the present invention relate to verification tokens used to verify the calibration of apparatus for the testing of trace chemical samples collected from suspect objects for the presence of substances of interest such as explosives and/or illicit drugs. These apparatus may include, for example, ion mobility spectrometers (IMS) or ion trap mobility spectrometers (ITMS). The samples may be in the form of solids, liquids, or gasses. The collection of the samples may involve contacting a sample collection apparatus with the surface of a suspect object to transfer trace chemical samples onto a sample collection medium (a "swab").

In accordance with an aspect of the present invention there is provided a verification token for use in verifying the calibration of a sample analysis system. The verification token comprises a substrate including a test area, a sample of a contraband substance included in the test area, and a preservative for the contraband substance included in the test area.

In accordance with some embodiments, the contraband substance comprises an explosive.

In accordance with some embodiments, the verification token further comprises a sample of one of a narcotic and a narcotics surrogate.

In accordance with some embodiments, the explosive comprises one or more of trinitrotoluene (TNT), cyclotrimethylenetrinitramine (RDX), and pentaerythritol tetranitrate (PETN).

In accordance with some embodiments, the preservative comprises one of potassium nitrate and sodium nitrate.

In accordance with some embodiments, the preservative comprises ammonium nitrate.

In accordance with some embodiments, the preservative further comprises one of potassium nitrate and sodium nitrate. In accordance with some embodiments, the ammonium nitrate is provided on the substrate at a ratio of between about 0.23 ng of ammonium nitrate and about 0.59 ng of ammonium nitrate per ng of explosive.

In accordance with some embodiments, the preservative reduces an amount of degradation of an indicia of presence of the explosive in the sample analysis system by greater than about 25% over a period of about 90 days at standard temperature and pressure (20° C and 1 atm) as compared to a verification token having the explosive included thereon in the absence of the ammonium nitrate over a period of about 90 days at standard temperature and pressure (20° C and 1 atm).

In accordance with some embodiments, the preservative reduces an amount of degradation of the indicia of the presence of the explosive by greater than about 85% over a period of about 90 days at standard temperature and pressure (20° C and 1 atm) as compared to a verification token having the explosive included thereon in the absence of the ammonium nitrate over a period of about 90 days at standard temperature and pressure (20° C and 1 atm).

In accordance with some embodiments, the verification token further includes a substance deposited on a portion of the substrate which undergoes a change of one of color and texture upon application of heat.

In accordance with another aspect of the present invention, there is provided a method for verifying the calibration of a sample analysis system. The method comprises obtaining a verification token comprising a substrate including a test area, a sample of a contraband substance included in the test area, and a preservative for the contraband substance included in the test area, analyzing the verification token in the sample analysis system, and determining if the sample analysis system outputs a result consistent with the presence of the sample of the contraband substance included in the test area.

In accordance with some embodiments, the contraband substance comprises an explosive selected from the group consisting of TNT, PETN, and RDX.

In accordance with some embodiments, the preservative comprises a nitrate species. In accordance with another aspect of the present invention, there is provided a method of forming a verification token for use in verifying the calibration of a sample analysis system. The method comprises obtaining a substrate, introducing a sample of a contraband substance to a portion of the substrate, and introducing a preservative for the contraband substance to the portion of the substrate. In accordance with some embodiments, the contraband substance comprises an explosive material.

In accordance with some embodiments, the explosive comprises one or more of TNT, PETN, and RDX.

In accordance with some embodiments, the preservative comprises a nitrate species.

In accordance with some embodiments, the nitrate species comprise ammonium nitrate.

In accordance with some embodiments, between about 0.23 ng of ammonium nitrate and about 0.59 ng of ammonium nitrate per ng of explosive are introduced to the portion of the substrate.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:

FIG. 1 is a plan view of an embodiment of a verification token;

FIG. 2 is a plan view of another embodiment of a verification token;

FIG. 3 is a plan view of another embodiment of a verification token;

FIG. 4 is a plan view of another embodiment of a verification token;

FIG. 5 is a plan view of another embodiment of a verification token;

FIG. 6 is a plan view of another embodiment of a verification token;

FIG. 7 is a table illustrating various combinations of substances which may be included in embodiments of a verification token;

FIG. 8 is a chart illustrating the results of a first test of the degradation of indicia of the presence of various substances included in a verification token in a sample analysis system; and

FIG. 9 is a chart illustrating the results of a second test of the degradation of indicia of the presence of various substances included in a verification token in a sample analysis system. DETAILED DESCRIPTION

This invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," "having," "containing," "involving," and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

The collection of trace samples from objects for testing for the presence of contraband such as explosives or illicit drugs has become a concern in recent years, especially in environments such as airports or other transportation hubs. It is believed that the testing of suspect packages or other objects for the presence of contraband may serve to deter the trafficking of drugs and/or explosives for nefarious purposes such as criminal activities or terrorism.

A method for testing for the presence of contraband involves the collection of particles and/or liquid samples from a surface of a suspect object and/or of vapors emanating from a suspect object on a sampling medium and analyzing the collected particulate, liquid, and/or vapor sample for the presence of contraband materials. In some methods, test samples are collected on swabs. Swabs may be formed from a sheet of substrate material. The substrate material may be, for example, paper, a fabric such as cotton or polyester, a polymer such as polyimide, polyamide, or polytetrafluoroethylene (PTFE), or in some examples, a screen or mesh of fiberglass or of a metal such as stainless steel. In some methods, a sample is transferred from a surface of an object of interest onto a swab by wiping the swab over a portion of the surface of the object. In other methods, a vapor emanating from an object of interest and/or air that is blown across a surface of the object is directed onto a test swab where particulates and/or vapors may be trapped. In some methods a vacuum generator is utilized to pull gas containing vapors and/or suspended particulates from the object of interest into the swab. In instances where it is desired to collect samples by passing potentially contaminated air through the swab, the swab may be sufficiently porous to provide for passage of air through the swab yet sufficiently thick to collect a desired amount of sample material to test. In some instances, swabs are impregnated with one or more materials, for example, activated carbon, which may enhance the ability of the swab to collect materials of interest.

Once a sample has been collected on a swab, the swab may be transferred into an analysis/detection system to check for the presence of contraband. Appropriate test systems may include, for example, gas chromatographs, mass spectrometers, fourier transform infrared spectrometers, ion trap mobility spectrometers, ion mobility spectrometers, and other systems known in the art for the analysis and/or identification of trace samples of materials. In some instances, the testing system may heat the swab to vaporize contraband particles and/or liquids which may be present and analysis is performed upon the vapor. An example of such an analysis system is the Ionscan 500 DT® dual-mode (explosive and narcotic) detection instrument available from Smiths Detection, a division of Smiths Group pic, London, England.

To facilitate proper operation of an analysis/detection system for the detection of trace levels of contraband, it may be desirable to periodically calibrate the analysis/detection system. Calibration of an analysis/detection system on a periodic basis may be desirable to facilitate the continued accuracy of measurements performed by such systems. The calibration of the analysis/detection system may include introducing a calibrant into the analysis/detection system. In some systems a calibrant may be introduced on a sample swab or by another mechanism from outside the analysis/detection system. In other systems, a calibration operation may be performed using a calibrant present or provided from within the body of the analysis/detection system.

To facilitate proper operation of an analysis/detection system for the detection of trace levels of contraband it may also be desirable to verify that the calibration of the

analysis/detection system was performed correctly. A method of verifying the calibration of an analysis/detection system may involve introducing a test swab contaminated with a known concentration of one or more substances of interest into the analysis/detection system and determining if the system produces an output consistent with what would be expected based on the one or more substances of interest on the test swab. A test swab or verification token may be used to facilitate verification of the calibration of analysis/detection systems such as the Ionscan 500 DT® dual-mode detection instrument. Embodiment of verification tokens described herein are not, however, limited to use with the Ionscan 500 DT® dual-mode detection instrument. Verification tokens as described herein may be utilized with any of a number of analysis/detection systems.

Verification tokens ("tokens") may be provided in different shapes. A verification token may be provided as a square or a rectangle of material, as illustrated at 100 in FIG. 1. A verification token may be provided as a circular or oval piece of material, as illustrated at 200 in FIG. 2, or as a triangular piece of material, as illustrated at 300 in FIG. 3. Verification tokens may have more complex shapes configured for use in specific analysis/detection systems, such as that illustrated at 400 in FIG. 4, which is similar in shape to a Model VT1336 Verification Trap, available from DSA Detection, North Andover, MA or as illustrated at 500 in FIG. 5, which is similar in shape to a Model SVT2602 Verification Token, also available from DSA Detection, or as illustrated in FIG. 6, which is similar in shape to a verification token which may be used with an Ionscan 500 DT® dual-mode detection instrument. Other shapes of verification tokens are also contemplated, and the present application is not limited to any particular shape of a verification token.

Embodiments of verification tokens in accordance with the present invention may be marked with a symbol or alpha-numeric character or characters which may identify these embodiments as verification tokens as opposed to, for example, test or sample swabs. Such symbols or alpha-numeric characters may be embossed, printed, formed from a cut-out, or otherwise placed or formed on the verification token. For example, as indicated at 410 in FIG. 4 and at 610 in FIG. 6, a "V" may be formed on a portion of the verification token to identify it as such.

Embodiments of verification tokens in accordance with the present invention may be provided with one or more features to identify a top surface and a bottom surface of the verification tokens. These features may include a marking which may be embossed, printed, or otherwise formed on the verification token. These features may also include a shaping of the token in a particular manner. For example, the verification token 500 of FIG. 5 has a rounded upper end and a squared lower end with a corner cut out at 510. The verification token 500 may have a top side that is always positioned on top when the rounded upper end is oriented in a forward direction and the cut out corner 510 is positioned on the right as illustrated in FIG. 5. In some embodiments, a compound of interest may be applied to only a single side of a verification token. Proper identification of the side of the verification token including the compound of interest may be important in properly mounting the verification token in a analysis/detection system for verification of the calibration of the analysis/detection system.

Verification tokens may be formed from materials similar to the materials used in test swabs. For example, verification tokens may be formed from sheets of a substrate material including, for example, paper, a fabric such as cotton or polyester, a polymer such as polyimide, polyamide, or PTFE, or in some examples, a screen or mesh of fiberglass or of a metal such as stainless steel. The token can also be formed from PTFE covered fiberglass or cotton muslin.

Embodiments of verification tokens in accordance with the present invention may include one or more compounds of interest present on a surface and/or embedded in the bulk material of the verification tokens and may also include a compound which serves as a preservative for one or more of the compounds of interest. These compounds of interest may include, for example, explosive materials and/or narcotics or other drugs, other contraband materials, and/or surrogate materials or analytes which may produce a similar signal in an analysis/detections system as one or more compounds of interest. In one specific example, a verification token may include one or more of trinitrotoluene (TNT),

cyclotrimethylenetrinitramine (RDX), pentaerythritol tetranitrate (PETN), ammonium nitrate (AN), and/or one or more narcotics surrogates which may, alone or in combination with one or more other analytes cause an analysis/detection system to output a signal consistent with the detection of one or more narcotics or other drugs. Examples of narcotics surrogates for use with various analysis/detection systems are known in the art.

One or more of compounds of interest may be impregnated into a verification token by a process of adsorption. In some embodiments, a standard solution including a known concentration or quantity of one or more compounds of interest may be applied to the substrate of a verification token. A liquid phase of the standard solution may then be evaporated, leaving behind a solid phase of the one or more compounds of interest in or on the substrate of the verification token. Alternate methods of applying a sample of explosive material to a verification token are known in the art and will not be described in detail here.

A verification token for use with an Ionscan 500 DT® dual-mode detection instrument might have, for example, the following combination and quantities of compounds included therein: Table 1 : Example of compounds in an embodiment of a verification token

In use, a verification token may be placed within an inlet of an analysis/detection system. Within the analysis/detection system, heat may be applied to the verification token to desorb one or more substances of interest from the verification token to release standardized amounts of the one or more substances of interest into the analysis/detection system.

Some explosive compounds, for example, TNT, PETN, or RDX may degrade, volatilize, oxidize, or otherwise break down over time. Thus, a verification token that is prepared with a known quantity of one or more explosive compounds may produce readings when read in an analysis/detection system that depend on the age of the verification token. This may result in a failure to properly verify the calibration of an analysis/detection system if verification of the calibration of the system was performed using one or more tokens which exhibited degradation of one more compounds of interest. The degradation rate of these compounds may vary with temperature, humidity, and/or other factors, rendering a prediction of an amount of degradation to be expected in a particular batch of verification tokens to be difficult to predict or ascertain.

It has been found that adding a suitable amount of AN to verification tokens including explosive compounds such as TNT, PETN, and/or RDX may reduce the rate at which these compounds break down. The AN may act as a preservative of one or more other compounds. The AN may reduce the rate of breakdown of one or more of TNT, PETN, and/or RDX. The rate of deterioration in a signal associated with one or more of these compounds observed in an analysis/detection system may change by approximately 25% or more over a time period of about three months (for example, from a reduction in an output signal associated with an explosive residue on a verification token of 25% to a reduction in an output signal associated with an explosive residue on a verification token of approximately 0% after 90 days). In some embodiments, the rate of deterioration may change by approximately 85% or more over a time period of about three months (for example, from a reduction in an output signal associated with an explosive residue on a verification token of 85% after 90 days to a reduction in an output signal associated with an explosive residue on a verification token of approximately 0% after 90 days).

In some embodiments, an amount of AN between about 100 ng and about 500 ng of AN may be provided as a preservative for a quantity of TNT, PETN, and/or RDX of between about 800 ng and about 2200 ng combined. Various examples of combinations of TNT, PETN, AN, RDX, and/or narcotics surrogate which may be provided on a verification token are illustrated in the table of FIG. 7. In the table of FIG. 7, 18 examples of possible combinations of TNT, PETN, AN, RDX, and/or narcotics surrogate (narcotics surrogate 1 and/or narcotics surrogate 2) which may be provided on a verification token are illustrated. The quantities of TNT, PETN, AN, RDX, and/or narcotics surrogate are indicated in units of nanograms (ng.) For example, the example of composition 1 indicates that a verification token may include 1,000 ng TNT, 700 ng PETN, 500 ng AN, and 250 ng of narcotics surrogate. These examples are not intended to be limiting. The quantities of any of TNT, PETN, AN, RDX, and/or narcotics surrogate included in a particular verification token may be different from any or all of the examples shown in FIG. 7.

In some embodiments, other compounds besides or in addition to AN may be utilized as preservatives for one or more explosive or other compounds in a verification token.

Examples of these other compounds include potassium nitrate (KNO₃), sodium nitrate (NaN(¾), or other nitrate or nitrite species.

In some embodiments, preservation of compounds such as TNT, PETN, RDX, and/or one or more narcotics surrogates may be enhanced by encapsulating these compounds on a verification token, for example, by forming a layer of wax on the verification token after one or more of these compounds has been introduced into or onto the surface of the token.

Verification tokens in accordance with embodiments of the present invention may include a substrate which includes one or more compounds of interest deposited and/or embedded in all portions of the substrate. In other embodiments, one or more areas of the substrate of a verification token may be free of explosives, narcotics, narcotics surrogate, or other compounds of interest. The provision of one or more areas of a verification token which are free from compounds of interest which might be used for the verification of the calibration of an analysis/detection system may facilitate handling of the verification token by a user with a reduced chance for contamination of the user's hands or gloves. This may reduce the potential for cross contamination of test swabs or surfaces which could lead to false positive readings from an analysis/detection system.

In one example, illustrated in FIG. 1, the substrate 110 of a verification token may include a test area 130. One or more compounds of interest may be included in the test area 130 of the verification token 100. The test area 130 may be surrounded by a handling area 120 which is free of, or which may have a reduced concentration of the one or more compounds of interest. In some embodiments, the handling area 120 may include a neutral filter or card material to which a test area comprising a substrate impregnated with one or more materials of interest is attached.

The handling area 120 may be sufficiently large that the verification token may be easily handled by a human operator without contacting the test area 130. The handling area 120 and the test area 130 may meet at a border 140. In some embodiments, the border 140 may be visually and/or tactilely discernable on the verification token 100. Providing for a visually and/or tactilely discernable border may facilitate the identification by an operator of what area(s) constitute a safe handling area for the verification token. The border 140 may be demarcated in various manners, including, for example, by embossing, by providing one ore more holes or apertures in the verification token substrate 110, or by printing of one or more lines, dots, or other indicator marks. The test area 130, handling area 120, and/or border 140 may be identified by any one or more of the methods for identifying a border portion and/or a working area of a test swab described in co-pending U.S. Patent Application No. 13/307,142 "EMBOSSED SAMPLE SWAB," filed November 30, 2011,which is incorporated herein by reference in its entirety for all purposes.

The verification token 100 may also be provided with one or more indicators, such as described in co-pending U.S. Patent Application No. 13/307,142 which may be used to align the verification token in an analysis/detection system. Proper alignment of the verification token in an analysis/detection system may facilitate proper verification of the calibration of the system. If the test area is not placed in a proper position in the analysis/detection system, a smaller than desired amount of the test area may be analyzed during the verification of the calibration of the analysis/detection system and/or analysis may be performed on part of the handling area of the verification token, leading to an improper amount of analyte material being introduced into the analysis/detection system, resulting in an improper calibration verification. Demarcation of one or more of a handling area 120, a test area 130, and a border 140 may also be provided in verification tokens having different shapes, for example, a circular verification token 200 as illustrated in FIG. 2 or a triangular verification token 300 as illustrated in FIG. 3. Although not illustrated, such demarcations may also be provided in the verification tokens illustrated in FIG. 4 or FIG. 5.

Demarcation of one or more of a handling area 120, a test area 130, and a border 140 may also be accomplished by forming one or more notches in portions of a verification token, such as notches 620 in portions of the periphery of the verification token 600 of FIG. 6. One or more notches 620 may also facilitate alignment of the verification token in an

analysis/detection system.

Although illustrated in FIGS. 1-3 as located within a handling region, a test area of a verification token including one or more compounds of interest need not be located centrally within a handling area. In other embodiments, a handling area may occupy, for example, a side, a portion of a side, an edge region, or a portion of an edge region of a verification token and a test area may occupy another portion of the verification token.

In some embodiments, a verification token may include one or more features which may provide an indication to a user of whether the verification token has been used. For example, a verification token may include a heat sensitive substance on or embedded in one or more regions of the verification token. The heat sensitive substance may change color or texture upon heating of the verification token in an analysis/detection system. A verification token for use with a particular analysis/detection systems may be provided with one or more heat sensitive substances which will react when exposed to the operation temperature of the analysis/detection system for which the verification token is intended to be used with. If an operator of an analysis/detection systems observes that the heat sensitive compound has reacted by changing color or texture, the operator will know that the verification token has been used and should be discarded rather than reused.

Example:

A pair of tests were performed to compare the degradation over time of signals associated with the detection of TNT residue and PETN residue in an analysis/detection system for tokens including AN with the degradation rate of these signals for tokens not including AN. 1,000 ng of TNT residue, 700 ng of PETN residue, and 250 ng of a narcotics surrogate were applied to each of a first set of tokens and a second set of tokens. No AN was added to the first set of tokens. 500 ng of AN was applied to each of the second set of tokens. The two sets of tokens were identical except for the addition of the AN to the second set.

The two sets of tokens were maintained in a room at atmospheric pressure and at room temperature without humidity control. The tokens were analyzed in an Ionscan 500 DT® dual-mode detection instrument at various points in time after the TNT residue, PETN residue, narcotics surrogate, and for the second set, AN, were applied to the tokens. Each token was discarded after being analyzed.

The results of the analysis for the two sets of tokens are illustrated in FIG. 8 and FIG. 9. FIG. 8 illustrates the analysis results for the first set of tokens. Each data point in FIG. 8 was obtained by analyzing two tokens from the first set and averaging the analysis results. FIG. 9 illustrates the analysis results for the second set of tokens. Each data point in FIG. 9 was obtained by analyzing either 10 or 15 tokens from the second set and averaging the analysis results. In these figures, the lines for "PETN-C" and "PETN-N" represent the strength of signals associated with the detection of two breakdown components of PETN. The lines for "TNT" represent the strength of signals associated with the detection of TNT residue. The lines for "V3" represent the strength of signals associated with the detection of the narcotics surrogate. The numbers for "CumA" on the Y-axes correlate to the strength of the signals associated with the detection of the presence of the various substances.

As can be seen from FIG. 8, the signals associated with the detection of the breakdown products of PETN residue on the first set of tokens decreased by greater than 25% (from a measurement level of greater than 2000 CumA to a measurement level of about 1500 CumA) over the course of about 90 days. The signal associated with the detection of the TNT residue on the first set of tokens decreased by greater than 85% (from a measurement level of greater than 3000 CumA to a measurement level of about 400 CumA) over the same time period.

For the tokens treated with AN, the results illustrated in FIG. 9 show that there was no significant amount of reduction in the strength of the signals associated with the detection of either the TNT residue or the PETN residue over a period of over 100 days. In FIG. 9 it can be seen that the strength of the signal associated with the detection of TNT residue actually appeared to increase slightly over time. For the PETN residue, the strength of the signals associated with the detection of the PETN-C decreased slightly over time while the strength of the signals associated with the detection of the PETN-N increased slightly over time.

These results indicate that AN can retard or even completely halt the breakdown of explosive residues of TNT and PETN over a period of 100 days or more. Specifically, the strength of the signals associated with the detection of PETN residue on a token was observed to decrease from a reduction by about 25% over a period of 90 days to no reduction over a similar time period when AN was included in the token. The strength of the signals associated with the detection of TNT residue on a token was observed to decrease from a reduction by about 85% over a period of 90 days to no reduction over a similar time period when AN was included in the token.

Having thus described several aspects of at least one embodiment of this invention, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Any one or more features of any of the embodiments described above may be combined. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the invention.

Accordingly, the foregoing description and drawings are by way of example only.

What is claimed is:

Claims

1. A verification token for use in a sample analysis system, the verification token comprising:

a substrate including a test area;

a sample of a contraband substance included in the test area; and

a preservative for the contraband substance included in the test area.

2. The verification token of claim 1 , wherein the contraband substance comprises an explosive.

3. The verification token of claim 2, wherein the verification token further comprises a sample of one of a narcotic and a narcotics surrogate.

4. The verification token of claim 2, wherein the explosive comprises one or more of TNT, PETN, and RDX.

5. The verification token of claim 3, wherein the preservative comprises one of potassium nitrate and sodium nitrate.

6. The verification token of claim 3, wherein the preservative comprises ammonium nitrate.

7. The verification token of claim 6, wherein the preservative further comprises one of potassium nitrate and sodium nitrate.

8. The verification token of claim 6, wherein the ammonium nitrate is provided on the substrate at a ratio of between about 0.23 ng of ammonium nitrate and about 0.59 ng of ammonium nitrate per ng of explosive.

9. The verification token of claim 2, wherein the preservative reduces an amount of degradation of an indicia of presence of the explosive in the sample analysis system by greater than about 25% over a period of about 90 days at standard temperature and pressure (20° C and 1 atm) as compared to a verification token having the explosive included thereon in the absence of the ammonium nitrate over a period of about 90 days at standard temperature and pressure (20° C and 1 atm).

10. The verification token of claim 9, wherein the preservative reduces an amount of degradation of the indicia of the presence of the explosive by greater than about 85% over a period of about 90 days at standard temperature and pressure (20° C and 1 atm) as compared to a verification token having the explosive included thereon in the absence of the ammonium nitrate over a period of about 90 days at standard temperature and pressure (20° C and 1 atm).

11. The verification token of claim 1, further including a substance deposited on a portion of the substrate which undergoes a change of one of color and texture upon application of heat.

12. A method for verifying the calibration of a sample analysis system, the method comprising:

obtaining a verification token comprising a substrate including a test area, a sample of a contraband substance included in the test area, and a preservative for the contraband substance included in the test area;

analyzing the verification token in the sample analysis system; and determining that the sample analysis system outputs a result consistent with the presence of the sample of the contraband substance included in the test area.

13. The method of claim 12, wherein the contraband substance comprises an explosive selected from the group consisting of TNT, PETN, and RDX.

14. The method of claim 13, wherein the preservative comprises a nitrate species.

15. A method of forming a verification token for use in verifying the calibration of a sample analysis system, the method comprising:

obtaining a substrate;

introducing a sample of a contraband substance to a portion of the substrate; and

introducing a preservative for the contraband substance to the portion of the substrate.

16. The method of claim 15, wherein the contraband substance comprises an explosive material.

17. The method of claim 16, wherein the explosive comprises one or more of TNT, PETN, and RDX.

18. The method of claim 17, wherein the preservative comprises a nitrate species.

19. The method of claim 18, wherein the nitrate species comprise ammonium nitrate.

20. The method of claim 19, wherein between about 0.23 ng of ammonium nitrate and about 0.59 ng of ammonium nitrate per ng of explosive are introduced to the portion of the substrate.