[0001] This application claims priority to U.S. provisional application 62/136,358, which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

[0002] The field relates to trace chemical detection, especially trace chemical detection using thin layer chromatography.

BACKGROUND

[0003] U.S. Pat. Publ. 2011/0239745 Al, the specification and drawings of which are hereby incorporated by reference, as background information on thin layer chromatography. This publication discloses the state of the art at the time the application was filed and a particular thin layer chromatography plate and development chamber for use in the field. However, the number of steps involved and the difficulty of performing those steps in the field, without contaminating the sample, the plate and/or the chamber, means that only specially trained personnel could use the kit and in a controlled environment, such as a portable or vehicle-mounted laboratory environment Specifically, the summary of the invention discloses the following components of a thin-layer chromatography kit as the invention: a container containing a solvent; a swab, a pipette, a thin-layer chromatography plate, a developing chamber, and a ultra violet light source. The invention requires the following steps: (i) provide a thin layer chromatography plate; (ii) wetting a swab is with a solvent; (iii) providing a wetted swab; (iv) contacting a location of interest with the wetted swab to obtain a sample; (v) placing the wetted swab with sample in the solvent to dissolve the sample in the solvent; (vi) dipping a micropipette into the solvent to obtain an amount of the solvent containing the sample; (vii) spotting the amount of the solvent and sample onto the thin-layer chromatography plate; (viii) allowing the amount of solvent and sample spotted onto the plate to dry; (ix) placing the spotted thin-layer chromatography plate into a developing chamber with a solvent mixture [contained in the bottom of the chamber]; (x) allowing the thin-layer chromatography plate to develop in the developing chamber; (xi) removing the developed thin-layer chromatography plate [after developing in the chamber]; and (xii) illuminating the developed thin-layer chromatography plate with ultraviolet light to produce an image for identifying the material present in the sample.

[0004] None of the known methods and kits can be used reliably in the field without

extraordinary training and creation of nearly laboratory conditions, because the thin-layer chromatography plates must be handled with great care and testing must be conducted without contaminating the plate, the sample and the chamber. In a field environment, with repeated exposure to explosives, narcotics or other substances to be detected, keeping preparation surfaces and temporary storage locations clean, while a sample spotting drys on a thin-layer

chromatography plate, before developing the thin-layer chromatography plate, requires the utmost care. Also, the person conducting the testing must be trained how to handle the plate, the correct amount of dilute sample to spot on the plate, and the correct way of inserting and the orientation of the plate during developing, after the plate is inserted into the developing chamber. Errors caused by operator error and contamination can lead to false negatives and false positives,which are both to be avoided in field situations, when delays caused by false positives or casualties caused by false negatives are unacceptable. The present inventions overcome these deficiencies and provide other advantages, allowing thin layer chromatography to be used in the field without extraordinary training and in operational environments.

[0005] U.S. Pat. Publ. 2014/0080129 discloses a known thin layer chromatography (TLC) system that is known in the art and use of a application on a cellphone for analyzing the results of the test. As in other known TLC systems, this system spots a plate, which comprises a sheet of glass, plastic or aluminum foil on which a thin layer of a stationary phase of an absorbent materials such as silica gel, alumina, or cellulose is deposited. Careful handling of the plate is required and it is first spotted and then placed in a housing with a mobile phase, which is a solvent or solvent mixture. A small sample of a specimen contained in a solvent is spotted on the plate within 1.5 centimeters of the bottom edge of the plate. The solvent is completely evaporated off. The plate is introduced into a transparent container and a small amount of an eluent (a mobile phase solvent) is added to a depth of 1 centimeter (less than the depth to the dried spot). A lid is provided that allows the solvent to saturate the volume in which the plate is contained, and the solvent wicks up the layer and elutes the specimen. When the solvent reaches a location near the top of the plate, the plate is removed and dried. Since different compounds are eluted at different rates by a solvent a separation occurs along the surface of the plate. A distance value referred to as Rf is determined, which be adjusted by changing the type of solvent of the mobile phase or the type or characteristics of the stationary phase. Various spots may be provided on the plate and the Rf of these spots and the specimen may be compared. In the publication, the cellphone application is used to analyze the Rf and to determine something about the specimen. Nevertheless, this apparatus uses known TLC technology for the plate and the container.

SUMMARY

[0006] A thin layer chromatography detector comprises a thin layer chromatography plate and plate carrier having a housing that protects the plate. In one example, a development chamber is compatible with the plate carrier and provides a means for accurately spotting a sample onto the plate and a means for delivering and containing a mobile phase during development. For example, the plate carrier is separate from the development chamber, providing for safe handling of the plate using the plate carrier and insertion of the plate carrier into the development chamber, such that the plate is held within the chamber at the correct orientation, reducing errors caused by contamination during transfer of the plate into the chamber and errors caused by improper orientation of the plate within the chamber.

[0007] In another example, the plate carrier is part of the development chamber. For example, the development chamber comprises a means for spotting the sample to the plate, without removing the plate from the chamber, a means for storing a mobile phase and a means for releasing the mobile phase and containing the mobile phase for development.

[0008] For example, a plate carrier may be comprised of an open case and a removable cap, closing one end of the open case. A thin layer chromatography plate may be disposed in the open case. For example, a housing of the open case may protect all but an exposed end of the plate, which extends beyond the open case. The exposed end of the plate may be immersed in a mobile phase within the development chamber. The removable cap fits on the open case and covers the exposed end of the plate, protecting the exposed end of the plate while the cap is in place. A person using the plate for thin layer chromatography can remove the cap, spot the plate with a drop of a sample to be tested, and insert the plate into the mobile phase within the development chamber without using tweezers or the like.

[0009] In another example, the plate carrier is integrated with the development chamber, such that the thin layer chromatography plate is not exposed, even at one end, further reducing the risk of contamination, which is difficult to avoid in the field. In practice, exposing an end of a plate in the field allows contaminants to reach the plate, creating conditions where results of testing may not be accurate, particularly when personnel conducting the testing are not well trained or conditions are conducive to keeping contaminants away from an exposed plate.

[0010] In one example, a thin layer chromatography apparatus comprises a substrate, a thin layer of an absorbent stationary phase on a surface of the substrate, the surface having a portion for use in thin layer chromatography testing, wherein a sample collected in a solvent may be deposited at a location within the portion and on the stationary phase near one end of the substrate, a first housing portion that prevents the substrate from moving in the first housing portion such that the portion of the surface does not touch any portion of the first housing portion, a second housing portion comprises a transparent material, the second housing portion matingly engaging the first housing portion such that a vapor volume is provided adjacent to the surface for vapor to saturate the vapor volume in proximity to the portion of the surface used for thin layer chromatography testing during testing and the transparent material of the second housing portion provides an unobstructed view of the portion of the surface for use in thin layer chromatography testing such that elution on the thin layer of absorbent stationary phase is visible through the transparent material of the second housing portion, a volume of a mobile phase, a fluid conduit fluidically coupling the volume of the mobile phase to a reservoir volume at a lower edge of the substrate, when the substrate is disposed within the housing for testing, and a portion of the thin layer of the absorbent stationary phase extends into the reservoir volume, an aperture disposed in the housing at a location near the lower edge of the substrate and above the portion of the thin layer of the absorbent stationary phase that extends into the reservoir volume, wherein the aperture provides an opening for spotting the surface of the portion with a sample to be tested, and the first housing portion and the second housing portion enclose the substrate during spotting of the stationary phase with the sample, drying of the sample, transfer of the mobile phase through the fluid conduit, and elution of the sample spotted on the stationary phase by the mobile phase. For example, the volume of mobile phase is contained in a breakable ampoule. The fluid conduit may be formed between the first housing portion and the second housing portion. The shape of the aperture may be funnel-shaped to hold a drop of sample solution within the aperture for spotting. For example, the aperture may be provided through a flexible material, such that the aperture makes contact with the absorbent stationary phase by flexing the material using a finger or thumb to press near the aperture. Alternatively, a spotting device may be used for transferring the sample to the absorbent stationary phase through the aperture. The spotting device may be a diaphragm button, for example. A vent, in addition to the fluid conduit, may fluidically couple vapor in the vapor volume to the volume of mobile phase. The first housing portion may comprise spacers for positioning the substrate within the first housing portion and the second housing portion.

[0011 ] In one example, an apparatus comprises a substrate; a thin layer of an absorbent stationary phase on a surface of the substrate, the surface having a portion for use in thin layer chromatography testing, wherein a sample collected in a solvent may be deposited at a location within the portion and on the stationary phase near one end of the substrate; a first housing portion that prevents the substrate from moving in the first housing portion such that the portion of the surface does not touch any portion of the first housing portion; a second housing portion comprises a transparent material, the second housing portion matingly engaging the first housing portion such that a vapor volume is provided adjacent to the surface for vapor to saturate the vapor volume in proximity to the portion of the surface used for thin layer chromatography testing during testing and the transparent material of the second housing portion provides an unobstructed view of the portion of the surface for use in thin layer chromatography testing such that elution on the thin layer of absorbent stationary phase is visible through the transparent material of the second housing portion; a volume of a mobile phase; a fluid conduit fluidically coupling the volume of the mobile phase to a reservoir volume at a lower edge of the substrate, when the substrate is disposed within the housing for testing, and a portion of the thin layer of the absorbent stationary phase extends into the reservoir volume; an aperture disposed in the housing at a location near the lower edge of the substrate and above the portion of the thin layer of the absorbent stationary phase that extends into the reservoir volume, wherein the aperture provides an opening for spotting the surface of the portion with a sample to be tested; wherein the first housing portion and the second housing portion enclose the substrate during spotting of the stationary phase with the sample, drying of the sample, transfer of the mobile phase through the fluid conduit, and elution of the sample spotted on the stationary phase by the mobile phase, and the volume of mobile phase is contained in a breakable ampoule, the breakable ampoule is disposed in a volume formed between the first housing portion and the second housing portion, and the fluid conduit is formed between the first housing portion and the second housing portion.

[0012] In one example, one of the housing portions comprises the substrate, and a thin film of absorbent material is deposited directly on the housing portion to form the stationary phase for thin layer chromatography. For example, the thin film may be disposed opposite of the second housing portion comprising a transparent material.

[0013] In one method of using the apparatus of, the method comprises selecting a sample to be tested by the apparatus; diluting the sample in a solvent to provide a sample solution; spotting the sample solution onto the surface of substrate through the aperture of the apparatus; drying the sample solution, without removing the substrate; introducing the volume of the mobile phase into the reservoir volume such that the mobile phase contacts a lower edge of the thin layer of the absorbent stationary phase on the surface of the substrate; eluting the sample, without removing the substrate; and observing the Rf of the eluted sample through the transparent material of the second housing portion without removing the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The following drawings are illustrative examples and do not further limit any claims that may eventually issue.

[0015] Figure 1 illustrates, schematically, a prior art process for thin layer chromatography (TLC) that separates one purple spot into a red spot and a blue spot, which is used for separating a mixture of two chemicals with different affinities for the functionalized silica particles provided on the plate.

[0016] Figure 2 illustrates a prior art plate and development chamber from U.S. Pat. Publ.

201 1/0239745 A1. [0017] Figure 3 illustrates a schematic side view of one example of a plate, a plate carrier and an end cap.

[0018] Figure 4 illustrates a profile view of another example of a plate, a plate carrier and a cap.

[0019] Figure 5 illustrates an exploded view of the example illustrated in Figure 4.

[0020] Figure 6 illustrates a schematic side view of an example of a stationary phase on a housing portion as the substrate and an integral cap.

[0021 ] When the same reference characters are used, these labels refer to similar parts in the examples illustrated in the drawings.

DETAILED DESCRIPTION

[0022] Figure 1 illustrates, schematically, a prior art process for thin layer chromatography (TLC) that separates one purple spot into a red spot and a blue spot, which is used for separating a mixture of two chemicals with different affinities for the funcu ^' onalized silica particles provided on the plate. For example, results of the process are determined by measuring the relative distances between the origin and the spots and the origin and the extent of the solvent (light blue mobile phase in the bottom of the container and extending up the plate in the original image), at the end of development time. Specifically, the diagram illustrates a first distance between the origin line 1 and the first spot 2 (blue in the original image), a second distance between the origin 1 and the second spot 3 (red in the original image), and a third distance between the origin 1 and the extent of the solvent migration 4. The ratio of the first distance and the third distance gives the Rf of the first spot. The ratio of the second distance and the third distance give the Rf of the second spot. In this example, the selected mobile phase solvent separates the blue dot and the red dot effectively, giving two Rf s that can be used in determining the chemical composition of the mixture.

[0023] Figure 2 illustrates a thin layer chromatography plate 210 in a development chamber 204 with a solvent 402 contained in the bottom of the chamber. As can be seen readily, the chamber is capable of being tipped or the mobile phase solvent 402 is capable of being sloshed about in the bottom of the chamber 204. The chamber 204 has a cap that seals the chamber 204 during development, but there is no plate carrier. Instead, the plate must be carefully handled using tweezers or the like to prevent damage to the plate or contamination of the plate 210. Also, the plate 210 is tilted in the chamber 204 at an angle, only if it is oriented as shown in Figure 2. Figure 2 is fully described in detail in U.S. Pat Publ. 201 1/0239745 Al .

10024] Figure 3 illustrates a schematic side view of an example of a plate, a plate carrier and an end cap that is an improvement over the kit described in U.S. Pat Publ. 2011/0239745 Al , and as illustrated in Figure 2. Specifically, the improvement adds a plate carrier I that is attached to the thin layer chromatography plate IV by one or more spacers II. The example shows a removable cap 111 that protects the plate during storage. The cap 111 is removable to expose only a bottom portion of the plate IV, for spotting and placing in a chamber, such as the chamber 204, illustrated in Figure 2, for example. The dimensions of the plate carrier I may be selected, such that the plate carrier I makes a tight seal with the chamber 204, eliminating the need for a cap. Notably, the plate carrier is not a cap and may be dimensioned to fit into the chamber.

Alternatively, the cap III may serve as a bottom portion of the chamber, if solvent is added to the cap III, and no separate development chamber is required.

[0025] Figures 4 and 5 illustrate a profile view and an exploded view of another example of a detector comprising a plate 60 contained in a plate carrier 54 and a cap 52. In this example, the cap 52 is fit onto the plate carrier 54, such as by a snap fitting, adhesive bond or the like. For example, a heat sealing bond may join the cap 52 to the plate carrier 54, such that the cap 52 is not removable from the plate carrier 54, and the seal that is formed is liquid tight For example, a breakable ampoule 70, such as an ampoule made of a thin, crushable glass or a rupturable bladder, may be inserted in blister packaging that forms a volume 51 in the cap 52, the plate carrier or both. Alternatively, a valve system may be used, disposing the mobile phase releasably in the volume 51 , when the valve is opened, such as by rupturing a rupturable seal or the like. For example, when crushed, the ampoule 70 releases a mobile phase that flows through a channel 56 and into a reservoir 58 formed in the plate carrier 54, the cap 52 or both. The plate carrier may have spacers 53, which may be formed in the plate carrier to carry a thin layer chromatography plate 60, disposed within a specific region of the the plate carrier 54. A vent 55 may be provided in the plate carrier 54, the cap 52 or both. The reservoir 58 may be shaped such that it acts as a stand, allowing the thin layer chromatography detector 50 to stand upright or at a fixed angle in relation to a flat surface. For example, having a fixed angle would allow the plate 60 to be disposed at a fixed angle, when the detector is supported by the bottom edge of the plate carrier 54 and the exterior of the reservoir 58. In the example shown, the cap 52 includes a funnel-shaped indentation and orifice 57, which allows a person using the kit to place a dilute sample precisely at the spot where it should be placed for accurately spotting the plate 60. For example, a removable, flexible diaphragm button 63 may be placed in an aperture through a portion of the housing 64, as illustrated schematically in Figure 6. A volume 65 is defined within the housing for a mobile phase, and the stationary phase 61 is a thin film of an absorbent material deposited directly on an inner surface of the housing 64, for example. When a flexible bulbous portion 62 of the diaphragm button 63 is pressed, a controlled transfer of a fixed volume of a dilute sample, such as one microliter, may be delivered directly to a spot on the stationary phase 61 , for example. For example, the entire button 63 may be removable to collect a volume of a sample before the sample is deposited on the spot.

[0026] Alternatively, the cap 52 may be made of a flexible material. By flexible, it is meant that the flexibility of the cap 52 should be sufficient to allow the nozzle of a funnel-shaped orifice to travel a distance of up to 3 millimeters in order for the nozzle to make direct contact with a surface of the plate 60 disposed opposite of the nozzle. In this manner, a micropipette or dropper can be used to drop a dilute sample into the funnel-shaped orifice 57 and the orifice 57 may be displaced into contact with the plate 60 by flexing the cap 52 by pressing with one or more thumbs on the surface of the cap 52 adjacent to the orifice 57, spotting the sample exactly where it should be spotted. This prevents smearing of the sample spot and reduces inconsistency in the positioning of the spot and spot size, for example. In one example, a plug or closure is provided to seal the orifice 57. For example, the button 63 may act to seal a funnel-shaped aperture.

[0027] In one example, a method of using the detector 50 lays the detector 50 on its side with the plate carrier 54 facing a supporting surface. A dilute sample is prepared as disclosed in the background and is added to the funnel-shaped orifice 57. such as by a dropper, micropipette or the diaphragm button b. Then, the diaphragm button or the surface of the cap 52 is depressed, such that a drop of the dilute sample is precisely disposed on the surface of the thin layer chromatography plate 60. If very dilute, then this procedure could be repeated to add additional drops of the sample to the surface of the plate 60. When the correct amount of sample is added to the surface of the plate 60, then the detector 50 may be raised to an upright orientation either holding it in the operators hand or resting it on the bottom edge and the exterior of the reservoir 58, for proper orientation. The mobile phase contained in the volume 51 would be directed to the reservoir 58, such as by crushing the ampoule 70. The mobile phase would fill a lower portion of the reservoir 58 and contact the bottom of the plate 60, wicking up the plate and separating the components in the sample, as is known in thin layer chromatography, without exposing the plate, the inside of the chamber or the solvent, as is currently required with known devices. When the mobile phase reaches a solvent front line on the plate 60, which may be identical to the plates 210 disclosed in U.S. Pat. Publ. 2011/0239745 Al and Figure 2, for example, then the detector 50 may be tilted back, causing the mobile phase to drain away from the plate 60. For example, a venting system may be used to release the mobile phase as a vapor. Alternatively, the mobile phase could be drained. The examination of the plate 60 may proceed as is known in the art, for example.

[0028] For example, an ultraviolet light source may be used to examine the spots on the surface of the plate 60. For example, the material of the cap 52 is selected such that the plate 60 may be examined under ultraviolet light while still remaining in the detector 50. For example, a plastic, such as a polyethylene, may be selected. In an alternative example, the plate 60 could be removed from the detector 50. In another example, if further staining or storage was required, the staining agent could be added to the detector or included within the detector for use in subsequent steps required in the process of analysis. If removed from the container, the plate 60 could be transferred with the plate carrier 54, for example.

[0029] In one example, the plate carrier I of Figure 3 may be incorporated within the detector 50 of Figure 4, allowing the plate IV to be removed as a single unit with the plate carrier I. In this example, the plate 60, of Figure 4, schematically represents the combined carrier I and plate IV of Figure 3, for example, allowing the plate to be extracted from the detector 50 for further staining, testing, storing or other subsequent processing.

[0030] The only known devices that can conduct thin layer chromatography without exposing the plate during the testing are high performance, automated laboratory devices that are unsuitable for field use and require trained operators familiar with the computerized controls and setup needed to operate them. These are laboratory instruments. The advantages of a simple, easy to use thin layer chromatography detector for field use will be understood by a person having ordinary skill by the examples provided.

[0031] This detailed description provides examples including features and elements of the claims for the purpose of enabling a person having ordinary skill in the art to make and use the inventions recited in the claims. However, these examples are not intended to limit the scope of the claims, directly. Instead, the examples provide features and elements of the claims that, having been disclosed in these descriptions, claims and drawings, may be altered and combined in ways that are known in the art