Patent Publication Number: US-2022229017-A1

Title: Apparatus and methods for preparation and introduction of trace samples into an ionizing detection system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. application Ser. No. 16/804,787 filed Feb. 28, 2020 which is related to and claims benefit of U.S. Provisional Application No. 62/816,253 filed Mar. 11, 2019, the entire contents of which are incorporated herein by reference. 
    
    
     STATEMENT OF GOVERNMENT INTEREST 
     This invention was made with government support under grant numbers HSHQDC-15-C-B0051 and HSHQDC-16-A-B0008 awarded by the DHS/ST. The government has certain rights in the invention. 
    
    
     BACKGROUND OF THE DISCLOSURE 
     The present invention generally relates to chemical detection systems and more specifically to illicit and dangerous substance trace detection systems, which are used in airports and other facilities for screening. 
     Ion Mobility Spectrometry (IMS) and Mass Spectrometry (MS) are known techniques for chemical detection. 
     Ion Mobility Spectrometry (IMS) is an atmospheric pressure chemical detection technology that is, in many ways, similar to Time-of-Flight Mass Spectrometry. Samples need to be in a gas phase for detection with an IMS system. Vaporized samples containing the analyte of interest are analyzed directly by drawing them into the IMS air flow system. Trace levels of explosive materials, drugs and chemical warfare agents can all be detected in this way. In existing IMS systems, samples are driven from a substrate or swab by applying heat from a desorber. Thus, non-volatile materials cannot be detected. Heat results in their decomposition rather than their desorption. 
     Sample material released into the IMS instrument by thermal desorption is then ionized to form reactant ion species from the gas employed in the system, normally air. Mixing these stable reactant ion clusters with vapor samples to be analyzed can result in ionization of the sampled materials, thus forming ion clusters characteristic of the sample material. A small cloud of formed ions is guided by an electromagnetic field through a drift tube towards a detector, where they eventually strike a collector electrode to produce a signal. Ions travel through the drift tube guided by the electromagnetic field and opposed by a gas countercurrent. As a result, characteristic clusters of ions are formed and separated based on analytes&#39; size, shape and cross-sectional area, which in turn produce specific drift speeds that can be further correlated to a calibration standard to create a final plasmogram result. 
       FIG. 1  illustrates, as prior art, an early portable IMS instrument generally indicated at  10 . A swab  12 , which has sampled an area of interest, is held in front of the inlet slot with a holder  14 . A desorber heater heats the air around the swab or the swab itself to release volatile trace chemicals from the sample swab. Once inside the instrument  10 , the gas analyte is ionized and passes through various magnetic grids to the collector/detector. 
     Mass Spectrometry (MS) is a similar analytical technique because it requires ionization of chemical species, but unlike IMS it sorts the ions based on their mass-to-charge ratio. Another difference of MS is their requirement to operate under low vacuum conditions (˜10 −3 -10 −11  bar), unlike stand-alone IMS detection systems that work under atmospheric pressure conditions (i.e., ˜1 bar). There are IMS devices that were integrated with MS instruments as hybrid or tandem designs and operate at lower pressures, but they lose their stand-alone functionality (i.e., being hand-held or easily portable, not requiring pumps and specialty gases, mobile, simple for user operation and accessible). These IMSs are no longer viewed as its own device, since it is an extension of MS and serves purely as a chromatographic (i.e., separation) addition prior to mass spectrometric (mass-to-charge) detection, with no ability of performing detection on its own. Mass spectrometry is used in many different fields and is applied to pure samples as well as complex mixtures. 
       FIG. 2  is a schematic of an exemplary magnetic sector mass spectrometer (MS) instrument generally indicated at  20 . In a typical MS testing procedure, a sample, which may be solid, liquid, or gas is first converted to vapor (operation not shown on schematic). The vapor  22  is ionized in an ionization region  24 , for example by a corona discharge needle. This may cause some of the molecules in the sample to break into charged fragments. These ions are then separated according to their mass-to-charge ratio, typically by driving them in an acceleration region  26  and then subjecting them to an electromagnetic field  28 . Ions of the same mass-to-charge ratio will undergo the same amount of deflection by the electromagnetic field  28 . The ions are counted by a detector  30 , such as an electron multiplier. Results are displayed as spectra of the relative abundance of detected ions as a function of the mass-to-charge ratio. The original structure of the analyte can be elucidated by the observed mass-to-charge ratio and characteristic fragmentation pattern. 
     For a number of different purposes, including environmental testing, law enforcement, security and field detection, samples requiring MS or IMS analysis are collected on swabs. 
       FIGS. 3 a -3 c    illustrate a prior art rectangular swab  50  and holder  52  and introduction of the swab  50  into an exemplary prior art IMS instrument  54  for testing. At the present time, swabs collected for travel security screening are tested directly without further sample preparation primarily because of time and technique constraints. This is a balance between adequate security and the need to move people through checkpoints at a reasonable pace. 
       FIG. 4  illustrates another prior art swab  60  and holder  62 . 
       FIG. 5  still further illustrates additional swab shapes  70 ,  80 ,  90  currently being used in industry. 
     For obvious reasons, the reliability and speed of testing of the collected swabs is critical, for particularly for security screening at travel checkpoints, i.e. airports, cruise and border crossing. Accordingly, there is a perceived need for enhancement of the sample preparation to improve testing results without sacrificing testing speed. 
     SUMMARY OF THE INVENTION 
     The present disclosure teaches a novel sample preparation technique and provides a swab holder/positioner which aids in the delivery of the analyte into the instrument inlet and concurrently serves as an ionization source. 
     The technique includes adding a solvent to the swab to better dissolve and release any trace chemicals contained on the swab, charging of the solvated swab to create an ionized analyte prior to entry into the detection instrument, and positioning of the charged swab so that a sharp corner, or a shaped angled tip of the swab faces the inlet into the detection instrument. The technique may be referred to as Ambient Desorption Ionization (ADD. 
     In some embodiments, buffers and an internal standard are added to the solvent to normalize detection peaks and calibrate the detection scheme in bother MS and IMS. 
     In some embodiments where the swab includes pre-existing corners, i.e. 90 degree square corners, or otherwise, the swab can be used without modification (see swabs  50 ,  70 ,  80 ,  90  as illustrated in  FIGS. 3 a    and  5 ). 
     As a first step in the technique, the swab is positioned so that an optimally angled corner or tip (analyte release area) faces the instrument inlet port to aid in creation of a directed ionized plume at the inlet of the detector. The swab is preferably held in an adapter/holder which is integrated into, or is configured for mounting onto, or positioning in front of, an existing MS/IMS detector device so that the corner or angled tip is within ±5 cm of the entrance to detector. The adapter positions the swab and provides the high voltage connection. A solvent supply for the technique may also be supported by the adapter/holder. 
     The sample swab is energized by applying a high voltage to ionize the analyte and create ions which are directed toward the detector inlet. The detector inlet is grounded or has a differential potential in order to attract the ionized species into the detector inlet. The existing detector units thereafter function as intended for analysis. 
     In the alternative, if the swab lacks a pre-existing corner, such as the round swab  60  illustrated in  FIG. 4 , it can be quickly modified by cutting or otherwise shaping the swab. A shaping punch tool can be provided to quickly cut the swab  60  and create the desired angled tip or corner. 
     Additionally, some embodiments may utilize a swab with a pre-formed triangular analyte release area. The pre-formed area may be perforated or otherwise cut to provide the required triangular apex release shape. 
     The novel technique is thus intended to improve release of chemical residue from the sample swabs and improve detection. Sample introduction and ionization are combined in a single step process making this invention particularly useful for MS/IMS, since this new technique allows nonvolatile compounds to enter and flow through the instrument. 
     The invention advantageously allows the use of existing swabs directly as the ionization source, given the availability of a high voltage supply internal or external, and eliminates the need for other types of ionization sources, for example radioactive material or corona discharge. 
     The ability to use present swab materials and holders is critically important in large scale deployment of the technique, and depending on the IMS or MS device, the present technique and adapter may require no change in swab materials; and if the instrument is presently portable, it remains so. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       While the specification concludes with claims particularly pointing out and distinctly claiming particular embodiments of the instant invention, various embodiments of the invention can be more readily understood and appreciated from the following descriptions of various embodiments of the invention when read in conjunction with the accompanying drawings in which: 
         FIG. 1  illustrates an exemplary prior art Ion Mobility Spectrometer (IMS); 
         FIG. 2  illustrates an exemplary prior art magnetic sector Mass Spectrometer (MS); 
         FIGS. 3 a -3 c    illustrate a prior art sample swab (rectangular), wand and detector instrument; 
         FIG. 4  illustrate a round or circular prior art swab and wand; 
         FIGS. 5 a -5 c    illustrate additional prior art swabs which have angled corners 90-120 degrees; 
         FIG. 6  schematically illustrates the preparation technique and release of the analyte from the sample in accordance with the present disclosure using an unmodified swab; 
         FIG. 7  illustrates an exemplary testing instrument including the present sample preparation apparatus; 
         FIGS. 8 a -8 c    schematically illustrate exemplary positioning angles for holding the sample swab in front of the inlet port of the testing instrument; 
         FIG. 9  illustrates a circular sample swabs and an exemplary stamp or punch which is configured to cut/shape the circular swab to provide it with an analyte release tip having preferred release angle; 
         FIG. 10  is another schematic illustration of the exemplary testing instrument with the shaped swab as illustrated in  FIG. 9 ; 
         FIG. 11  illustrates an exemplary holder or adapter for positioning of the swab or shaped swab and for application of the solvent to the swab; 
         FIGS. 12 a -12 d    illustrate test data showing the same or similar performance between the present ADI technique and an ElectroSpray Ionization (ESI) technique on an LTQ-Orbitrap instrument; 
         FIGS. 13 a -13 d    illustrate additional test data showing the same or similar performance between the present ADI technique and ESI on an LTQ-Orbitrap instrument; 
         FIG. 14  illustrates examples test results of explosive detection using ADI on an Explosive Trace Detector (ETD) Device; 
         FIG. 15  illustrates examples test results of explosive detection using ADI versus desorption on a standard ETD Device; 
         FIGS. 16 a -16 d    illustrate examples of detection of Nitrate-, Perchlorate-, Chlorate-Salts and TNT on an Excellims IMS Device with MS Confirmation; 
         FIG. 17  is a plan view of another exemplary pre-formed sampling swab; 
         FIG. 18  is a perspective view thereof; 
         FIG. 19  is a schematic illustration of the exemplary swab of  FIGS. 17 and 18  deployed with a novel swab holder, positioner and voltage supply arrangement; 
         FIGS. 20A-D  are various view of the swab holder and positioner with the integrated voltage delivery contact positioned below the swab; 
         FIG. 21  illustrates an exemplary compact Mass Spectrometer (MS) device with the swab holder/positioner and integrated solvent dispenser mounted to an inlet port of the MS device; 
         FIG. 22  is a side view of the swab holder and integrated solvent dispenser; 
         FIG. 23  is a top view thereof; 
         FIGS. 24A-D  are various view of the swab holder/positioner showing deflection of the flanking side portions of the preformed swab and presentation of the apex of the analyte sensing area; 
         FIG. 25  illustrates ethanol (200 proof) solvent peaks (among many other solvents) ionization (5.7-8.5 ms range) on Excellims IMS, using ADI- with 10 μl deposition; 
         FIG. 26  illustrates and analysis of sodium nitrate (6.7-6.8 ms), potassium chlorate (6.9-7.0 ms) and ammonium perchlorate (7.2-7.3 ms) on Excellims IMS, using ADI- with 10 μL ethanol (200 proof) desolvation solvent deposition; 
         FIG. 27  illustrates a side-by-side analysis of an ethanol buffered solvent with and without an internal standard; 
         FIG. 28  illustrates peak analysis of potential threats which show up in negative ionization; and 
         FIG. 29  illustrates peak analysis of potential threats which show up in positive ionization. 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
     Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the device and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present invention is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present disclosure. Further, in the present disclosure, like-numbered components of the embodiments may have similar features, and thus within a particular embodiment each feature of each like-numbered component is not necessarily fully elaborated upon. Additionally, to the extent that linear or circular dimensions are used in the description of the disclosed systems, devices, and methods, such dimensions are not intended to limit the types of shapes that can be used in conjunction with such systems, devices, and methods. A person skilled in the art will recognize that an equivalent to such linear and circular dimensions can easily be determined for any geometric shape. Further, to the extent that directional terms like proximal, distal, top, bottom, up, or down are used, they are not intended to limit the systems, devices, and methods disclosed herein. A person skilled in the art will recognize that these terms are merely relative to the system and device being discussed and are not universal. 
     Referring now to the drawings, exemplary embodiments of the invention are generally described and illustrated in the attached figures. The present disclosure teaches a novel sample introduction technique and provides an adapter/holder which aids the delivery of the analyte into the testing instrument inlet and concurrently can serve as an ionization source. The technique includes adding a solvent, charging the swab to create an ionized analyte plume, which, due to positioning of the swab corner or shaping of the swab, more efficiently directs the ion plume into the entry of the detection device. 
     Referring now to  FIGS. 6-11 , the technique and adapter/holder apparatus are illustrated in accordance with the invention. A swab is generally indicated at  100  and includes an optimally angled analyte release area  102  having an apex angle measuring from about 30 degrees to about 120 degrees. The illustrated example is a conventional rectangular swab having a distal end with a pre-existing corner angle of about 90 degrees. Any existing swab material may be utilized, although materials with a rougher surfaces, grooves or channels may produce improved results. A particularly suitable sampling swab material is described in U.S. Pat. No. 9,200,992, the entire contents of which are incorporated herein by reference. 
     In use, the swab  100  will be contacted with an object to be tested and will thereafter carry a trace chemical residue  104 . 
     An MS or IMS instrument is provided and generally indicated at  106 . The MS/IMS instrument  106  is conventional in the art and generally operational as described hereinabove. The instrument  106  has a housing  108  and an inlet port  110 . Generally described, to create an ionized plume of analyte directed into the inlet  110  of the instrument  106 , an optimally angled corner or tip (analyte release area)  102  of the sample swab  100  is pointed at and preferably positioned within ±5 cm of the inlet port  110  of the instrument  106 . 
     A solvent supply is provided and generally indicated at  112 . The solvent supply  112  includes a container  114  for holding the solvent  116  and a dispenser  118  which may be advantageously positioned to selectively apply solvent  116  to the swab  100 . 
     Solvents  116  may include water, methanol, ethanol, isopropanol or other alcohols, acetonitrile, acetone, benzene, hexane, ethyl acetate, DMF, THF, a combination of solvents, or aqueous buffers. Ethanol may be considered a preferred solvent. 
     Use of an aqueous buffer allows introduction of potential adduct forming species or dopants. Examples of such species include chloride, formate, acetate, ammonium, sodium, potassium, nitrate. 
     A high voltage source  120  is provided for charging of the swab  100  and generally includes a ground  122 . Where necessary for safety the ground can be provided by connection to the instrument inlet port  110 . A power contact (+/−)  124  which is connected to the swab  100  is essential to the technique. In this regard, in order to grab or hold the swab  100  and provide the needed charge adjacent to the analyte release area  102 , the apparatus may include a contact clip  126  which may have spring fingers (as illustrated) which frictionally grasp the swab  100 . The clip  126  may also comprise a spring-loaded clamp or clip device. The contact clip  126  is preferably a disposable component which can be discarded after each use to prevent cross-contamination from one sampling swab to another. In this regard, the body of the clip is releasably connected with the power contact  124 , in a sliding socket  128  (as illustrated), or otherwise as known in the connector art. 
     Turning now to  FIG. 7 , the swab  100  is mounted in/positioned on an adapter/holder  130  which is configured for mounting onto the exterior housing  108  of an existing detector-device  106 . In the illustrated example, the holder  130  is received on the housing  108  of the MS/IMS device  106  and provides a platform  132  on which the sampling swab  100  can be positioned adjacent to the inlet port  110 . The holder  130  has an adapter  134  (spring clip) which may frictionally hold the swab  100  in a desired position. Alternately, as seen in  FIG. 11 , the adapter  134  may be provided in the form of a plastic molded holder into which the swab  100  is positioned and held. The adapter  134  may then be snap received or otherwise removably positioned or mounted onto the platform  132 . The adapter  134  may also provide a solvent guide port  136  which may be connected with the solvent supply dispenser  118 . 
     Referring briefly to  FIG. 8 , the inlet port  110  has a defined entry plane ( FIG. 8 a   ) A and as earlier noted, the +/−5 cm positioning is defined as the tip area  102  being positioned somewhere between 5 cm inside the inlet port  110  or within 5 cm in front of the inlet port  110 .  FIGS. 8 b  and 8 c    also illustrate that the platform  132  of the holder  130  can be angled or tilted 0-30 degrees upward or downward or to the left or right to provide improved gravitational disbursement of the solvent  116 . 
     The swab holder  130  allows support of the swab  100  and direct application of an adjustable voltage (0.5V to 50 kV but less than 10 kV of floating voltage is preferred) directly behind or on or slightly above the solvated sweet spot to ionize the analyte and create an ion plume  140  directed toward the detector inlet (See  FIG. 6 ). The voltage supply  120  may be provided with a switch  142 , which may be on the holder  130 , or elsewhere, to selectively apply the voltage as desired. As noted above, the inlet port  110  is grounded or held at a differential potential. The differential potential created between the swab  100  and the entrance  110  to the IMS or MS  106  acts as the equivalent of electrospray ionization and drives the analyte toward the detector inlet  110 . 
     Alternatively, the holder  130  may be configured for placement in front of the instrument  106  so that currently deployed detector units can still be utilized. Still further, the apparatus as described herein may be fully integrated with the MS/IMS instrument for a complete integrated instrument. 
     Turning to  FIG. 9 , if the swab has no corner, such as the circular swab illustrated in  FIGS. 4 and 9 , then the swab  100 A can be cut or otherwise shaped to form an optimally angled tip area  102 A. An exemplary angle is approximately 45 degrees but may be less or greater ranging from 30 degrees (See  FIG. 11 ) up to and including about 120° as desired. The release area  102  may also be slightly truncated or flattened. Shaping may be accomplished by any number of means, such as manual scissors, or an external punch device  144 , folding, or a pre-perforated swab (not shown) may be provided which is separated along the perforations, and/or a premade channel to direct charge and solvent. 
     Exemplary test data for the present ADI sampling and preparation method are illustrated in  FIGS. 12-16 . The proposed ADI technique was evaluated on commercially available instruments—Thermo LTQ Orbitrap XL mass spectrometer and Excellims attached to a Thermo Exactive mass spectrometer. The samples were prepared from neat materials by diluting them in appropriate solvent (e.g. acetonitrile, methanol, ethanol, isopropanol, water, but any other solvent can be used). For sample introduction, a direct infusion into the MS was employed. Resulting spectra was collected and averaged over at least 25 scans (acceptable number of scans for statistical verification of sample average response). The precursor ion was isolated and resonance energy was increased (CID in eV) until characteristic products were produced from corresponding ion. ADI produced virtually identical spectra to that of established ESI technique. Additional parameters were tested to verify the versatility of the proposed innovation. Many compounds do not ionize on their own, but can accept nearby charged species as carriers, thus forming what is known as adducts. ADI was tested on whether most common adducts can be produced (e.g. chloride, acetate, formate, ammonium, sodium, etc.) and produced spectra was compared to prior art ESI technique. The adduct was introduced directly by dissolving ammonium chloride (200 μM) in the solvent system designed for delivery. (see  FIGS. 12 and 13 ). 
     The proposed technique was further tested on commercially available IMS systems to verify its applicability. The ADI source was positioned directly at the inlet of the Ion Track IMS. The power source was attached directly to the swab, which was manipulated (positioned or shaped) so that a point was directed toward the inlet of the instrument, and the voltage was controlled though the charger interface (3-20 kV). Once the sample was ionized and grounded to the entrance of the IMS, the scan initiation was manually triggered to acquire the chromatogram ( FIGS. 14 and 15 ). To ensure there was no carry over or false positive results, the system was first cleared out, and then a blank sample was run that contained only solvent system but no analyte immediately followed by ADI introduction technique with analyte present. 
     ADI was further tested by coupling it to IMS (Excellims)/MS (Thermo Exactive high accuracy mass spectrometer) system. This setup gives the ultimate confirmation of 1) ionization efficiency, 2) analytes&#39; true identity via accurate mass confirmation, and 3) robustness of the ADI via semi-quantification mechanisms. The setup provided unequivocal confirmation of ADI source suitability for coupling with IMS/MS systems for which it was originally intended for. The presence of non-volatile compounds corresponding to m/z of nitrates, perchlorates and chlorates in the spectra of MS ( FIG. 16 ) upon selection of the peaks in IMS confirmed that ADI can move non-volatile compounds into a gas phase without their decomposition. Alternatively, organic compounds (e.g. TNT) can also be detected without visible degradation allowing for wider application of ADI source in comparison to thermal desorber. 
     Turning to  FIGS. 17 and 18 , there is illustrated and disclosed a novel pre-configured shaped swab  200  which is generally rectangular in shape and may be provided with a triangular analyte release area  202  having a pointed tip with apex angle of between 30 and 120 degrees. The triangular analyte release area  202  may be pre-perforated in the body of the swab or pre-cut. The central analyte release area  202  is centered between flanking side portions  204  which serve to retain the general rectangular shape of the swab for better retention in a conventional swabbing wand. The flanking side portions  204  may be connected forward of the tip or may be separated. An exemplary apex angle is approximately 45 degrees but may be less or greater within the noted range. 
     As described above, the swab  200  may be rubbed across a surface to collect potential analytes onto the analyte release area  202 , or it could remain stationary having the potential analyte placed onto the release area  202 . In either case, the swab  200  containing the potential analyte must be presented to the detection instrument, and for this a holder is required. 
     Referring to  FIGS. 19 and 20A -D, the apex tip shape of the swab  200  is important for creation of a “Taylor” cone of ions directed into the inlet  410  of the detection device  400  (See  FIG. 19 ). The above-described swab  200  fits into a holder  300  which requires no support of the swab  200  by the user during use.  FIGS. 19 and 20A -D illustrate an exemplary configuration of a swab holder  300  comprising a body or housing  302  with a swab positioning slot  304  for receiving a swab  200 , a dispensing nozzle  306  for dispensing a solvent  307 , and a voltage delivery contact  308 . The housing  302  is configured with deflection arms  310  to receive the pre-configured swab  200  and deflect the flanking side portions  204  downwardly out of the way such that the pointed release area  202  can be positioned immediately adjacent to and directed towards the grounded detector inlet  410  or entrance. The voltage delivery contact  308  is configured and mounted within the housing  302  between the deflector arms  310  such that the analyte release area  202  is engaged with the contact  308  when fully inserted into the slot  302  and properly positioned and spaced at the detector entrance  410 . 
     Referring to  FIGS. 21 through 24D  there is illustrated an MS or IMS instrument generally indicated at  400  which incorporates the novel swab holder positioner apparatus  300  as described above. In some embodiments, the swab holder/positioner apparatus  300  is configured to be secured to the device housing with brackets  420  or other fasteners which properly align the device  300  for presentation of the analyte release area with the inlet  410 . 
     The MS/IMS instrument  400  may be conventional in the art and generally operational as described hereinabove. While the above embodiments were primarily described in connection with an exemplary IMS device, the present configuration is an exemplary MS testing device, such as an Advion™ ExpressionCMS™ (Comact Mass Spectrometer). Other MS type devices are also contemplated within the scope of the present disclosure. 
     The instrument  400  has a housing  402  and an inlet port  410 . Generally, as described, to create an ionized Taylor Cone plume of analyte directed into the inlet  410 , the tip (analyte release area  202 ) of the swab  200  is pointed at and may be positioned within 5 cm of the inlet port  410 . In some embodiments, the distance may be varies and the tip  202  may be positioned slightly above the inlet axis. 
     The swab holder/positioner apparatus  300  generally comprises a housing  302  with a swab positioning slot  304  extending through the housing for receiving swab  200 , a solvent dispenser  320  including a solvent supply container  322  containing a solvent  307 , a solvent dispenser nozzle  306  positioned adjacent to the analyte release area  302  and a pump  324  in fluid communication with the solvent supply container  322  and the solvent dispenser nozzle  306 . The holder/positioner  300  may further include an integrated a high voltage supply  305  including delivery contact  308  and a ground communicating with the device inlet  410 . 
     The housing  302  is configured with deflection arms  310  to receive the pre-configured swab  200  and deflect the flanking side portions  204  downwardly out of the way such that the pointed release area  202  can be positioned immediately adjacent to and directed towards the grounded detector inlet or entrance  410 . The housing  302  may further be provided with a cross-bar or other deflection structure  330  extending across the slot  304  for deflecting the analyte release area upwardly for better presentation without user handling. 
     In another embodiment of the housing where the swab has been preshaped angles are already within the described angles 30-120 degree, in particular 90 degrees, the housing angles the swab so that the desired apex may be positioned within 5 cm of the inlet port  410 . 
     The voltage delivery contact  308  is configured and mounted within the housing  302  between the deflector arms  310  such that the analyte release area  202  is engaged with the contact  308  when fully inserted into the slot  304  and properly positioned and spaced at the detector entrance  410 . The apparatus allows support of the swab  200  and direct application of an adjustable voltage (0.5V to 50 kV but less than 10 kV of floating voltage is preferred) directly to the solvated analyte release area  202  to ionize the analyte and create an ion plume (Taylo Cone) directed toward the detector inlet  410 . The voltage supply  305  may be provided with a switch  332  to selectively apply the voltage as desired. As noted above, the inlet port  410  is grounded or held at a differential potential. The differential potential created between the swab  200  and the entrance  410  to the MS acts as the equivalent of electrospray ionization and drives the analyte toward the detector inlet. 
     The voltage may be provided from above, below or on the side of the swab; however, it is generally, advantageous that the voltage be applied on the opposite side of the swab as the application of solvent, but this is a space consideration, not a requirement of the structure or method. 
     The solvent supply pump  324  may be manually actuable or electrically powered and may be selectively actuable to dispense a predetermined volume of solvent  307  from the solvent supply container  322  through said dispensing nozzle  306  and onto the analyte release area  202 . A small amount of solvent  307  aids the movement of the analyte across and off the matrix (swab) toward the inlet of the detection device. It is not desired that solvent enter the detection device; therefore, the solvent amount is kept small, e.g. 10 microliters, but may range from 1 microliter to 100 microliters. The solvent is expected to evaporate (vaporize) leaving charged analyte ions to enter the detection device. It may be necessary to keep the inlet area slightly warm and/or provide a gentle breeze to aid solvent evaporation. 
     The exemplary embodiment includes a commercial pump  324  which dispenses the desired amount of solvent, e.g. 10 microliters. The pump  324  may be positioned over the swab holder housing  302  as illustrated or beneath the housing  302  and pumped upwardly with a dispensing nozzle over the analyte release area. Positioning of the swab  202  within the holder slot  304  could trigger the release of the solvent or the solvent could be released by a separate switch/button  326 . Applying the solvent via a wicking action either from the top or bottom of the swab is also feasible. Solvent should be applied either just behind or directly on the area where the sample is positioned on the swab. 
     Solvent Standard and Ionization Suppression 
     The ionization of analytes is a driving force behind the detection of the analyte in ion mobility spectrometry (IMS) and in mass spectrometry (MS). If ionization is somehow suppressed, then the analyte of interest produces little signal in the detector. Ionization suppression can happen because other species in sample (the matrix with the analyte) “steal” the charge. Ionization suppression often happens during analysis of complex matrices (e.g. blood, plasma, tissue, soil, run-off water, waste water, or in general any organic, inorganic, polymeric, natural and synthetic materials). Ionization enhancement can also happen, and is the opposite of ion suppression, i.e. observable signal intensity is increased. In either case, the minimization of these effects is preferable, especially for quantification and detection applications. 
     In ADI application, swabs (or any other sample introduction or separation platforms, e.g. TLC plates, 2D printed microchannel plates, etc.) are used as a platform for sample collection and/or introduction into the IMS/MS device. A solvent or a mixture of solvents is then used to solvate analytes off the surface of the collection platform. High voltage is supplied to analyte release area on the swab/platform where the solvent is then ionized and drives the analytes into the IMS or MS devices, while transferring its charge to the analyte. 
     The use of solvent in the ADI method introduces the possibility to predominantly ionize solvent and not analyte of interest. This can result in an ion suppression of the analyte. In IMS that uses drift time as the main metric for analytes discrimination, the solvent molecules can obscure detection of analytes if they have similar drift times. 
     Referring to  FIG. 25  there is shown an ion mobility spectrometry trace of 200 proof ethanol. The response observed in the 5.7 to 8.5 ms range is from the solvent alone. All solvents potentially used in ADI produced some sort of response: methanol; acetonitrile, isopropyl alcohol, acetone; water; DMSO; methylene chloride; 50/50 ethanol/water. Such response from these various solvents could preclude detection of analytes whose drift times overlap with solvent peaks. Their responses can be obscured or produce false positive results. In either case this is unwanted outcome for testing and detection purposes. However, it has been found that adding certain analyte species or the analyte itself to the solvent suppressed the ionization of the solvent, allowing the analytes (example nitrates, chlorates and perchlorates) as illustrated in  FIG. 26 , to be observed in a clean IMS trace. 
     Additionally, it has been discovered that addition of certain compounds can suppress ionization of solvent peaks, but not affect ionization of analytes. These “suppressant” standards can be directly added to the solvent or a mixture of solvents at parts-per-million levels or embedded into the sample collection/ionization platform. “Suppressants” can be tuned to cover specific drift time region and/or ionization potential (i.e. positive or negative). The same “suppressant” can be used for positive and negative ionization mode (assuming it is capable of both positive and negative ionizations in the first place). 
     To be introduced into the solvent system, the suppressant standards require multi-day stability in the solvent and must not, themselves, have drift times that overlap with the analyte(s) of interest. 
     Examples of such species include but is not limited to sulfates, sulfonates, phosphates, phosphides, chlorides, chlorates, perchlorates, nitrates, nitrites, and ammonium and phosphonium salts. Specific examples include but not limited to sodium dodecylbenzenesulfonate, 3-(1-pyriclinio)-1-propanesulfonate, sodium diphenylamine-4-sulfonate; sodium trifluoromethane sulfonate, potassium phthalate monobasic, tetrabutylammonium phosphate; tetraphenylphosphonium chloride; benzylpyridinium salts. 
     These compounds serve two purposes, namely that of suppressing solvent signal (as discussed above), and that of providing a benchmark for the observed drift times so that daily instrument and ambient fluctuations can be accounted for. 
       FIG. 27  illustrates a side-by-side analysis of an ethanol buffered solvent with and without an internal standard and a comparison of multi-day stability within the solvent. 
       FIG. 28  illustrates peak analysis of potential threats which show up in negative ionization and  FIG. 29  illustrates peak analysis of potential threats which show up in positive ionization. 
     While there is shown and described herein certain specific structures embodying various embodiments of the invention, it will be manifest to those skilled in the art that various modifications and rearrangements of the parts may be made without departing from the spirit and scope of the underlying inventive concept and that the same is not limited to the particular forms herein shown and described except insofar as indicated by the scope of the appended claims