Abstract:
Methods and devices for detecting a target substance on a subject without contacting the subject are disclosed. At least one air jet blows analyte from a surface of the subject into an airflow, the airflow entraining the analyte. A desorption channel desorbs molecules from analyte in a portion of the airflow travelling through the desorption channel. An ionizer forms ions from vapour molecules in the portion of the airflow. At least one mass spectrometer analyzes the ions to detect the target substance. The flow travels without interruption from the subject to the at least one mass spectrometer. The desorption channel causes a sufficient quantity of molecules to desorb from the analyte to enable the at least one mass spectrometer to detect the target substance.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims benefit of U.S. Provisional Application No. 61/490,807, filed on May 27, 2011, the entire contents of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to non-contact trace chemical screening to detect residues of target substances, such as, for example, narcotics, explosives, poisons or the like. More specifically, the present invention relates to a device for non-contact trace chemical screening, and a detection method. 
       BACKGROUND OF THE INVENTION 
       [0003]    At many locations, maintaining security of access requires screening subjects who enter the location for contraband substances. For example, at airports, passengers and luggage are screened for narcotics and explosives. Similar screening is performed at other locations where security of access is important, such as train stations, border crossings, public buildings, government offices, sporting facilities, tourist attractions, mail depots, etc. The subjects to be screened may be persons, parcels, packages, baggage, electronic devices, tickets, and any other subjects which may have come into contact with a target substance. 
         [0004]    At locations where subjects must pass through at a high rate, screening may create a bottleneck. It is therefore desirable at such locations to screen subjects quickly. It is also often desirable to screen subjects in a minimally-intrusive way to avoid any unnecessary invasion of privacy. 
         [0005]    Trace chemical screening devices detect a target substance, such as a narcotic or an explosive chemical, based on the presence of minute quantities of molecules or ions from residues of the target substance. Thus, compared to metal detectors which screen only for metallic contraband such as weapons, and x-ray machines which screen based on bulk shapes that resemble contraband, trace chemical screening devices may be used to screen for a broader range of target substances, while performing screening at greater sensitivity and selectivity. Trace chemical screening devices may therefore be used in place of, or in conjunction with conventional detection devices such as metal detectors and x-ray machines. 
         [0006]    An exemplary trace chemical screening devices is disclosed in U.S. Pat. No. 7,458,283 to Nacson et al. According to Nacson et al, analyte is sampled from the subject by wiping the surface of the subject with a swab. The device then uses a spectrometer to analyze swabbed analyte to determine if a target substance is present. 
         [0007]    Trace chemical screening devices which screen subjects without requiring any physical contact with the subject, and are therefore less intrusive than the device disclosed in Nacson et al., are also known. Exemplary non-contact trace chemical screening devices are disclosed in U.S. Pat. No. 5,915,268 to Linker et al. and U.S. Pat. No. 6,610,977 to Megerle. According to Linker et al. and Megerle, analyte is collected from a subject by blowing air onto the subject to entrain analyte into an airflow. Analyte may include residues of the target substance in particle or vapour form. The airflow containing the analyte is sampled, and a detector is used to analyze analyte within the sampled air to determine if a target substance is present. Linker et al. and Megerle disclose a variety of detectors, including detectors which perform detection using ion mobility spectrometry, electron capture detection, and gas chromatography/chemiluminescence. 
         [0008]    One problem associated with conventional non-contact trace chemical screening devices lies in providing a detectable concentration of the target substance to the detector. The concentration of the target substance carried in the sampled air may often fall below the detector&#39;s sensitivity threshold. As such, a preconcentrator may be used to increase the concentration of the target substance to level above the detector&#39;s sensitivity threshold. 
         [0009]    However, when a preconcentrator is used, sampled air containing analyte is not provided directly to the detector. Rather, sampled air is first passed through the preconcentrator, which forms a concentrated sample by accumulating analyte from the sampled air over time. For example, the preconcentrator may include an activated carbon filter to absorb analyte from sampled air passing through the preconcentrator. 
         [0010]    After the preconcentrator accumulates a sufficient quantity of analyte, the concentration of the target substance in the concentrated sample is increased to a level above the detector&#39;s sensitivity threshold. The concentrated sample is then provided to the detector to detect the target substance. 
         [0011]    While a preconcentrator enables non-contact trace chemical screening devices to detect low concentrations of the target substance in sampled air, the use of a preconcentrator introduces a number of problems. Firstly, the use of a preconcentrator may consume materials such as activated carbon, thereby increasing operational costs. Secondly, the use of a preconcentrator increases screening time per subject, as additional time spent accumulating sufficient quantity of analyte, thereby reducing detection throughput. 
         [0012]    Accordingly, there remains need for an improved non-contact chemical screening device. 
       SUMMARY OF THE INVENTION 
       [0013]    In an aspect of the present invention, there is provided a device for detecting a target substance on a subject without contacting the subject. The device includes at least one air jet for blowing analyte from a surface of the subject into an airflow, the airflow entraining the analyte; an inlet for receiving at least a portion of the airflow; a desorption channel in fluid communication with the inlet for desorbing molecules from analyte in the portion of the airflow travelling through the desorption channel; an ionizer, in fluid communication with the desorption channel, for forming ions from vapour molecules in the portion of the airflow; and at least one mass spectrometer in fluid communication with the ionizer, for analyzing the ions to detect the target substance. The airflow travels without interruption from the subject to the at least one mass spectrometer. The desorption channel causes a sufficient quantity of molecules to desorb from the analyte to enable the at least one mass spectrometer to detect the target substance. 
         [0014]    In a further aspect of the present invention, there is provided a method of detecting a target substance on a subject without contacting said subject. The method includes blowing analyte from a surface of the subject into an airflow, the airflow entraining the analyte; desorbing molecules from the analyte in the airflow, while the airflow travels without interruption from the subject to a tandem quadrupole mass spectrometer; ionizing vapour molecules in the airflow to form ions; and analyzing said ions using at least one mass spectrometer to detect the target substance. 
         [0015]    Other aspects and features of the present invention will become apparent to those of ordinary skill in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    In the figures which illustrate by way of example only, embodiments of the present invention, 
           [0017]      FIG. 1  is a schematic diagram of a non-contact trace chemical screening device for detecting a target substance on a package, exemplary of an embodiment of the present invention. 
           [0018]      FIG. 2  is a schematic diagram of a desorber of the non-contact trace chemical screening device of  FIG. 1 . 
           [0019]      FIG. 3  is a schematic diagram of a glow discharge ionizer of the non-contact trace chemical screening device of  FIG. 1 . 
           [0020]      FIG. 4  is a schematic diagram of a mass spectrometer of the non-contact trace chemical screening device of  FIG. 1   
           [0021]      FIG. 5A  is a perspective view of a non-contact trace chemical screening device for detecting a target substance on a person, exemplary of another embodiment of the present invention. 
           [0022]      FIG. 5B  is a schematic diagram of the non-contact trace chemical screening device of  FIG. 5A . 
           [0023]      FIG. 6A  is a perspective view of a non-contact trace chemical screening device for detecting a target substance on a ticket, exemplary of another embodiment of the present invention. 
           [0024]      FIG. 6B  is a schematic diagram of the non-contact trace chemical screening device of  FIG. 6A . 
       
    
    
       [0025]    In the drawings, preferred embodiments of the invention are illustrated by way of example. It is to be expressly understood that the description and drawings are for the purpose of illustration and as an aid to understanding, and are not intended as a definition of the limits of the invention. 
       DETAILED DESCRIPTION 
       [0026]      FIG. 1  shows a non-contact trace chemical screening device  10 , exemplary of an embodiment of the present invention. Non-contact trace chemical screening device  10  may be used to detect a target substance on packages such as package  14 . Device  10  includes a conveyer belt  28  for carrying packages through a detection area; a plurality of air jets  12  in the detection area for blowing analyte from package  14  into an airflow; a desorber  30  for desorbing molecules from analyte carried in the airflow through desorber inlet  18 ; a fan  22  for drawing the airflow through desorber  30 , and for exhausting waste airflow from desorber  30  out of device  10 ; an ionizer  40  for ionizing vapour molecules in a portion of the airflow received from desorber  30 ; and a mass spectrometer  50  for analyzing ions in the portion of airflow received from ionizer  40  to detect the target substance. 
         [0027]    Air jets  12  are selected to blow air with sufficient pressure to lift analyte from the surface of package  14 . Any of air jets  12  may of a conventional variety, such as AiRTX® Model 48009, capable of blowing air with pressure in the range of 40 psi to 100 psi. 
         [0028]    In the embodiment depicted in  FIG. 1 , four air jets  12  are used. A fewer or greater number of air jets  12  may also be used. A person skilled in the art will understand that in some embodiments, a single air jet may be sufficient to lift analyte from the surface of package  14 . 
         [0029]    As depicted in  FIG. 1 , air jets  12  are disposed at the top of the detection area to blow air downwards at package  14  from a distance of approximately 100 mm to 500 mm. Air jets  12  may also be disposed elsewhere around the perimeter of the detection area, for example, to blow air at package  14  from the sides or from the bottom of the detection area. The distance between air jets  12  and package  14  may also be varied, so long as sufficient pressure is applied to lift analyte from the surface of package  14 . 
         [0030]    Fan  22  is selected to draw a sufficient volume of air carrying analyte from package  14  through desorber  30  for a sufficient quantity of molecules of the target substance to desorb from the analyte for detection. Fan  22  may of a conventional variety, such as GAST® Blower R4P115 which operates at approximately 50 rpm to 60 rpm. 
         [0031]    As illustrated in  FIG. 2 , desorber  30  includes a desorber inlet  18  for receiving airflow entraining analyte from the detection area, a desorption channel  38  through which airflow passes, a desorber waste outlet  20  for exhausting waste airflow out of desorber  30 , and a heater  36  for heating airflow traveling through desorption channel  38  to effect thermal desorption of molecules from analyte entrained in the airflow. 
         [0032]    Desorption channel  38  is enclosed by sidewalls, creating a substantially or completely sealed path through which airflow travels. The path created by desorption channel  38  has a cross-sectional area of approximately 0.8 mm 2  to 135 mm 2 , and preferably between 1.5 mm 2  to 10 mm 2 . In some embodiments, the cross-sectional area of desorption channel  38  may vary along its length. The path created by desorption channel  38  path has a length of approximately 50 mm to 200 mm, and preferably between 80 mm to 120 mm. 
         [0033]    Desorption channel  38  may include one or more bends  32  to induce desorption through collision of analyte entrained the airflow. Bends  32  typically have an angle of 90 degrees, but other sharp angles suitable for inducing desorption through collisions may also be used. 
         [0034]    Desorber  30  is designed to cause a sufficient quantity of molecules to desorb from the analyte to enable mass spectrometer  50  to detect the target substance. Desorption in desorber  30  increases the concentration of vapour molecules of the target substance a level above the sensitivity threshold of mass spectrometer  50 . Consequently, desorber  30  does not include a preconcentrator to accumulate analyte molecules for detection over time. This allows airflow to travel from package  14  through desorber  30  to mass spectrometer  50  without interruption. 
         [0035]    Heater  36  is selected to heat desorption channel  38  to effect thermal desorption. A suitable range for the temperature of the airflow in the desorption channel  28  to effect thermal desorption is 80° C. to 300° C., and preferably between 150° C. to 250° C. Heater  36  may of a conventional variety, such as the Watlow® FireRod® heater, which operates at approximately 100 watts to 1000 watts, and preferably between 200 watts to 300 watts. 
         [0036]    In some embodiments, desorber  30  may include additional spaced-apart heaters (not shown) along the length of desorption channel  38 . Multiple heaters may be used to improve the temperature profile along the length of desorption channel  38 . 
         [0037]    As illustrated in  FIG. 3 , ionizer  40  includes primary plates  41  and  42  for forming an ionizing glow discharge, secondary plates  43  and  44 , also for forming an ionizing glow discharge, and a vacuum pump  48  for reducing air pressure within ionizer  40 . Primary plate  41  has an aperture  45  for receiving airflow from desorber  30  via ionier inlet  24 . Similarly, primary plate  44  has an aperture  46  for sending ions to mass spectrometer  50  via mass spectrometer inlet  26 . Aperture  45  has a diameter of approximately 100 μm to 500 μm, while aperture  46  has a diameter of approximately 600 μm to 1000 μm. In some embodiments, the diameters of apertures  45  and  46  may be adjustable. 
         [0038]    Ionizer inlet  24  may include a pump (not shown) for drawing air through ionizer inlet  24 . Ionizer inlet  24  may further include a filter (not shown) to prevent solid particles, water vapour molecules, or other unwanted substances from entering ionizer  40 . 
         [0039]    Ionizer  40  ionizes vapour molecules entrained in the portion of the airflow entering via ionizer inlet  24  using an ionization method commonly known as glow discharge ionization, as described, for example, in Scott A. McLuckey et al., “Atmospheric Sampling Glow Discharge Ionization Source for the Determination of Trace Organic Compounds in Ambient Air“, Analytical Chemistry, Vol. 60, No. 20, Oct. 14, 1988, pp. 2220-2227, and U.S. Pat. No. 4,849,628 to McLuckey et al. The contents of both documents are hereby incorporated by reference. 
         [0040]    In an alternate embodiment, ionizer  40  may be replaced with an ionizer performing ionization according to other ionization methods. In an alternate embodiment, ionizer  40  may be replaced with an ionizer producing ions according to a chemical ionization method, as described in U.S. Pat. No. 6,037,587 to Dowell et al., the contents of which are hereby incorporated by reference. According to this chemical ionization method, ions are produced by colliding vapour molecules with ions of a reagent gas. 
         [0041]    In a another alternate embodiment, ionizer  40  may be replaced with an ionizer producing ions according to electron ionization (also known as electron impact ionization), as described, for example, in Jürgen Gross,  Mass Spectrometry: A Textbook,  2nd ed., Springer, 2011, the contents of which are hereby incorporated by reference. According to this electron ionization method, ions are formed by impacting vapour molecules with energized electrons within an electron beam. 
         [0042]    In another alternate embodiment, ionizer  40  may be replaced with an ionizer producing ions according to corona discharge ionization, as described in U.S. Pat. No. 7,326,926 to Wang, the contents of which are hereby incorporated by reference. According to this corona discharge ionization method, ions are produced by creating a potential difference of a few thousand volts between two electrodes. This potential difference ionizes vapour molecules surrounding the electrodes, resulting in a corona discharge. 
         [0043]    A person skilled in the art will understand that ionizer  40  may be replaced with other known ionizers capable of ionizing vapour molecules carried in the airflow. 
         [0044]    As illustrated in  FIG. 4 , mass spectrometer  50  includes a mass spectrometer inlet  26  for receiving ions from ionizer  40 , a first quadrupole  54  for performing mass filtering, a second quadrupole  56  in a collision chamber  58  for fragmenting ions, a third quadrupole  60  for performing further mass filtering, and a detector  62  for analyzing ions and ion fragments to detect the target substance. 
         [0045]    Mass spectrometer  50  may also include a communication interface (not shown) to facilitate communication with an interconnected computer. The communication interface may operate according to USB, RS-232, Ethernet, Wi-Fi™ or any similar interface capable of transmitting and receiving data between mass spectrometer  50  and an interconnected computer. The interconnected computer may be remotely-located and communicate with mass spectrometer  50  over a communication network. The communication network may be wired and/or wireless. 
         [0046]    Mass spectrometer  50  analyzes ions entrained in the airflow entering via mass spectrometer inlet  26 . Mass spectrometer  50  may be a tandem mass spectrometer, as described, for example, in Edmond de Hoffmann, “Tandem Mass Spectrometry: a Primer”, J. Mass. Spectrometry, Vol. 31, 129-137 (1996), the contents of which are hereby incorporated by reference. More particularly, mass spectrometer  50  may be a triple quadrupole tandem mass spectrometer, as depicted in  FIG. 4 . A conventional triple quadrupole tandem mass spectrometer, such as the Ionics 3Q Molecular Analyzer™ mass spectrometer from Ionics Mass Spectrometry Group™ may be used. 
         [0047]    In an alternate embodiment, mass spectrometer  50  may be replaced with a different type of spectrometer, such as an ion trap mass spectrometer, a time-of-flight mass spectrometer, or an ion mobility spectrometer. Ion trap mass spectrometers and time-of-flight mass spectrometers are described, for example, in Jürgen Gross,  Mass Spectrometry: A Textbook,  2nd ed., Springer, 2011. Ion mobility spectrometers are described, for example, in Gary Alan Eiceman and Zeev Karpas,  Ion mobility spectrometry,  2nd ed., CRC Press, 2005, the contents of which are hereby incorporated by reference. 
         [0048]    Multiple spectrometers may be further combined to increase sensitivity or selectivity. For example, in an alternate embodiment, mass spectrometer  50  may be replaced with a time-of-flight mass spectrometer combined with an ion trap mass spectrometer. 
         [0049]    Any spectrometer or combination of spectrometers may be used so long it provides sufficient sensitivity and selectivity to detect the target substance from the quantity of analyte carried by the airflow without interruption from package  14  through desorber  30  and ionizer  40  to mass spectrometer  50 . 
         [0050]    Non-contact trace chemical screening device  10 , as depicted in  FIGS. 1-4 , may be operated as follows. 
         [0051]    As depicted in  FIG. 1 , conveyer belt  28  carries package  14  into a detection area within device  10  within range of air jets  12 . Conveyer belt  28  may carry package  14  at a speed of approximately 50 cm/s to 200 cm/s. Conveyer belt  28  may carry package  14  through the detection area without stopping, or alternatively, may pause temporarily to keep package  14  within the detection area for a sufficient duration to allow device  10  to detect the target substance. 
         [0052]    While luggage  14  is in the detection area, air blown from one or more of air jets  12  strikes the surface of package  14  to create air disturbances  16 . Air disturbances  16  lift analyte from the surface of package  14  into an airflow, which immediately entrains the lifted analyte. Analyte may contain residues of the target substance in particle or vapour form. 
         [0053]    Air jets  12  may be operated to blow air in a continuous or pulsed fashion. In embodiments including more than one air jet  12 , air jets  12  may be operated concurrently or in a pre-determined sequence. Operation of air jets  12  is configured to maximize the quantity of analyte lifted from the surface of package  14  and then entrained in the airflow. 
         [0054]    Airflow carrying analyte is received by desorber  30  from the detection area via desorber inlet  18 . To cause a sufficient quantity of molecules of the target substance to desorb from the analyte for detection, fan  22  draws airflow through desorber  30  at a rate of approximately 10 L/min to 100 L/min, and preferably between 10 L/min to 20 L/min. For detection of the target substance on each package such as package  14 , approximately 0.1 L to 2 L, preferably 0.1 L to 0.3 L, of air is drawn through desorber  30 . 
         [0055]    As depicted in  FIG. 2 , the airflow travels along desorption channel  38  towards ionizer inlet  24  and desorber waste outlet  20 . While the airflow travels along desorption channel  38 , it is heated by heater  36 . Heating increases the volatility of analyte entrained in the airflow and thereby causes molecules to desorb from the analyte. 
         [0056]    As the airflow travels along desorption channel  38 , it strikes the wall of desorption channel  38  at sharp bends  32  to create collisions  34  resulting in heated airflow molecules. Collisions  34  between analyte and molecules in the airflow, and between analyte and the wall of desorption channel  38  causes further molecules to desorb from the analyte entrained in the airflow. 
         [0057]    While airflow travels along desorption channel  38 , desorption channel  38  causes a sufficient quantity of molecules to desorb from the analyte in the airflow to enable mass spectrometer  50  to detect the target substance. 
         [0058]    As molecules desorb from analyte entrained in the airflow traveling through desorption channel  38 , the molecules also become entrained in the airflow. A portion of this airflow, entraining vapour molecules, enters ionizer  40  through ionizer inlet  24  at a rate of approximately 0.3 L/min to 1.5 L/min, and preferably between 0.8 L/min to 1.2 L/min. The remainder of the airflow is drawn out of desorber  30  through desorber waste outlet  20  as exhaust airflow by fan  22 , as shown in  FIG. 1 . 
         [0059]    As depicted in  FIG. 3 , the portion of the airflow carrying vapour molecules enters ionizer inlet  24  and travels through ionizer  40  towards mass spectrometer inlet  26 . 
         [0060]    Vacuum pump  48  draws air out of ionizer  40  to reduce air pressure within ionizer  40  to between approximately 10 Pa and 300 Pa. A glow discharge is formed by operating ionizer  40  in one of two modes. In the first mode, a voltage difference of approximately 300 V to 500 V is created between primary plates  41  and  42 . This voltage difference may be achieved, for example, by applying approximately −400 V to primary plate  41  and either approximately −10 V to primary plate  42  when negative ions are desired, or approximately 10 V to primary plate  42  when positive ions are desired. This voltage difference produces a glow discharge which ionizes vapour molecules between primary plates  41  and  42 . In the second mode, a voltage difference of approximately 300 V to 500 V is created between secondary plates  43  and  44 , for example by applying approximately 200 V to secondary plate  43  and approximately −200 V to secondary plate  44 . This voltage difference produces a glow discharge which ionizes vapour molecules between secondary plates  43  and  44 . Ions formed by the glow discharge are then carried in airflow out of ionizer  40  through mass spectrometer inlet  26  into mass spectrometer  50 . 
         [0061]    Mass spectrometer  50 , as depicted in  FIG. 4 , analyzes positive and negative ions from ionizer  40  detect the target substance. 
         [0062]    First quadrupole  54  performs mass filtering of ions  52  to select a subset of ions based on specified m/z values. Second quadrupole  56  then fragments a portion of the selected ions to form fragment ions. Third quadrupole  60  then performs mass filtering of unfragmented ions and fragment ions to select a further subset of unfragmented ions and fragment ions based on specified m/z values. Detector  62  then performs mass analysis on this further subset of unfragmented ions and fragment ions. Based on this mass analysis, detector  62  determines if the target substance is present. 
         [0063]    In embodiments of mass spectrometer  50  with a communication interface, mass spectrometer  50  may communicate with an interconnected computer. This communication interface may be used to program mass spectrometer  50  to detect a particular target substance by specifying the m/z values to filter for the target substance, and by specifying the mass spectrum for the target substance. Mass spectrometer  50  may also be programmed to sequentially detect multiple target substances in analyte lifted from a single subject such as package  14 . This communication interface may also be used to communicate detection results to the interconnected computer. 
         [0064]    In the embodiment of non-contact trace chemical screening device  10  depicted in  FIGS. 1-4 , airflow carrying analyte travels without interruption from package  14  to mass spectrometer  50  in approximately 500 milliseconds to 2000 milliseconds. The total screening time for package  14 , including travel time of the airflow from package  14  to mass spectrometer  50 , is approximately 600 milliseconds to 2100 milliseconds. 
         [0065]      FIGS. 5A and 5B  show a non-contact trace chemical screening device  100 , exemplary of another embodiment of the present invention. Device  100  may be used to detect a target substance on persons such as person  114 . 
         [0066]    As illustrated in  FIG. 5B , device  100  includes a plurality of air jets  112  for blowing analyte from person  114  that become entrained in an airflow; a desorber  130  for desorbing molecules from analyte carried in the airflow from desorber inlet  118 ; a fan  122  for drawing the airflow through desorber  130 , and for exhausting waste airflow from desorber  130  out of device  100 ; an ionizer  140  for ionizing vapour molecules in a portion of airflow received from desorber  130 ; and a mass spectrometer  150  for analyzing ions in the portion of airflow received from ionizer  140  to detect the target substance. 
         [0067]    Device  100  may include a turnstile or gate (not shown) to restrict movement of person  114  through device  100 . 
         [0068]    In operation, person  114  walks through a detection area in device  100 . Person  114  may be stopped within the detection area for a sufficient duration to allow device  100  to perform detection of the target substance. 
         [0069]    While person  114  is in the detection area, one or more air jets  112  blows air towards person  114  to create air disturbances  116  on the skin and clothing of person  114 . Air disturbances  116  lift analyte from the skin and clothing of person  114  into an airflow, which entrains the analyte. 
         [0070]    Device  100  detects the target substance in entrained analyte from person  114  using desorber  130 , ionizer  140 , mass spectrometer  150  and fan  122  in substantially the same way as described above for device  10  using corresponding desorber  30 , ionizer  40 , mass spectrometer  50  and fan  22 . 
         [0071]      FIGS. 6A and 6B  show a non-contact trace chemical screening device  200 , exemplary of yet another embodiment of the present invention. Device  200  may be used to detect a target substance on tickets such as ticket  214  carried by person  218 . 
         [0072]    As illustrated in  FIG. 6B , device  200  includes a ticket slot  232  for receiving ticket  214 ; a plurality of air jets  212  for blowing analyte from ticket  214  into an airflow while it is inserted into ticket slot  232 ; a desorber  230  for desorbing molecules from analyte carried in the airflow; an ionizer  240  for ionizing vapour molecules in a portion of airflow received from desorber  230 ; a fan  222  for drawing the airflow through desorber  230 , and for exhausting waste airflow from desorber  230  out of device  200 ; and a mass spectrometer  250  for analyzing ions in the portion of airflow received from ionizer  240  to detect the target substance. 
         [0073]    Ticket slot  232  may include a ticket reader (not shown) such as a bar code reader, a magnetic stripe reader, or an integrated chip reader to read information from ticket  214 . Ticket slot  232  may also include a ticket validator to validate ticket  214  based on the information read. Ticket  214  may be an airplane boarding pass, such as would be used by person  228  during check-in at an airport. Ticket  214  may also be a subway ticket, an entry ticket for an entertainment facility, or the like. 
         [0074]    In operation, person  228  inserts ticket  214  into ticket slot  232 . While ticket  214  is inserted into ticket slot  232 , one or more air jets  212  blows air towards ticket  214  to create air disturbances  216  on the surface of the ticket  214 . Air disturbances  216  lift analyte from the surface of the ticket  214  into an airflow, which entrains the analyte. 
         [0075]    Device  200  detects the target substance in entrained analyte from ticket  214  using desorber  230 , ionizer  240 , mass spectrometer  250  and fan  222  in substantially the same way as described above for device  10  using corresponding desorber  30 , ionizer  40 , mass spectrometer  50  and fan  22 . 
         [0076]    In embodiments of ticket slot  232  including a ticket reader, the ticket reader may read information from ticket  214  while device  200  performs detection of the target substance. Additionally, information read from ticket  214  may allow ticket  214  to be validated and/or person  228  to be identified while target substance is detected by device  200 . 
         [0077]    Of course, the above described embodiments are intended to be illustrative only and in no way limiting. The described embodiments are susceptible to many modifications of form, arrangement of parts, details and order of operation. The invention, rather, is intended to encompass all such modification within its scope, as defined by the claims. 
         [0078]    Other features, benefits and advantages of the embodiments described herein not expressly mentioned above can be understood from this description and the drawings by those skilled in the art.