US3535086A

US3535086A - Portable unit for thin-layer chromatographic analysis

Info

Publication number: US3535086A
Application number: US679323A
Authority: US
Inventors: Albert D Baitsholts
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1967-10-31
Filing date: 1967-10-31
Publication date: 1970-10-20
Anticipated expiration: 1987-10-20
Also published as: DE1806150A1; FR1590325A; GB1211468A

Description

Oct. 20, 1970 A. D. BAITSHOLTS 3,535,036

PORTABLE UNIT FOR THIN-LAYER CHROMATOGRAPHIC ANALYSIS Filed Oct. 31, 1967 INVENTOR ALBERT D. BAITSHOLTS FIG. 3

ATTORNEYS Patented Oct. 20, 1970 3,535,086 PORTABLE UNIT FOR THIN-LAYER CHROMATOGRAPHIC ANALYSIS Albert E). Baitsholts, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Filed Oct. 31, 1967, Ser. No. 679,323 Int. Cl. B01d /08 U.S. Cl. 23-253 16 Claims ABSTRACT OF THE DISCLOSURE Apparatus for use in thin-layer chromatography comprising a substantially enclosed chamber formed by two sheets, a chromatographic sheet and a cover sheet, attached one to each side of a continuous, for example, a rectangular, frame. The apparatus may be made as a self-contained unit by mounting capsules in the chamber containing migrating solvent or other necessary chemicals and including devices for opening the capsules at will from outside the chamber.

BACKGROUNDFIELD OF THE INVENTION This invention relates to chromatography. In particular it relates to an improved simplified device for use in thin-layer chromatography, which device may be constructed as a self-contained unit for field use or the like.

BACKGROUNDDESCRIPTION OF THE PRIOR ART A modern form of chromatography is the so-called thin-layer chromatography. The name is based on the use of a sorption agent, usually an adsorption agent, in the form of a thin layer or an inert support. This arrangement possesses a number of known advantages as compared to other chromatography techniques such as paper chromatography, adsorption columns, etc.

One type of apparatus designed especially for use with thin-layer chromatography is that shown in US. Pat. No. 3,189,541 to Brenner et al. issued June 15, 1965. In the apparatus of Brenner et al. the thin-layer chromatographic adsorbent is coated on the surface of a plate of glass after which a thin gasket is placed along three edges of the plate and a second glass plate is placed over the adsorbent layer forming a thin layer or air gap between the two plates. The sandwich is held together by clamps placed about the sealed sides. This thin chamber equilibrates quickly with solvent vapor when the chromatogram is developed by placing the open end of the sandwich in a trough containing the migrating solvent. The quick and near complete saturation provided by this thin sandwich chamber is important in achieving optimum results from chromatographic analysis.

However, this previously known sandwich-type chromatographic chamber has at least one serious disadvantage in that it is quite inconvenient to operate. Operation of the apparatus requires many manipulative steps, that is, coating the first plate, arranging the gaskets and the second plate over the first plate, clamping the plates together, setting up the trough with the solvents, and linking the solvent with the adsorbent layer. Consequently, this apparatus would not lend itself to use outside of the laboratory.

SUMMARY OF THE INVENTION It is a purpose of the present invention to provide a sandwich-type chamber for use in thin-layer chromatographic analysis which is far more simple to use than apparatus known heretofore. It is a further purpose of the present invention to provide a sandwich-type, thinlayer chromatographic chamber which may be constructed as a self-contained unit containing not only the chromatographic sheet, but also the migrating solvent and all other elements required to carry out the chromatographic analysis, so that the unit may be conveniently used away from the laboratory for on-the-spot testing.

According to the present invention there is provided a chromatographic device comprising a frame member surrounding a chamber area and having two generally open parallel sides. While it is contemplated that the frame will be generally rectangular, the invention is not necessarily limited to a rectangular frame. Within this frame member the chamber proper is formed by attaching two sheets to the generally parallel sides of the frame. First, a chromatographic sheet comprising a smooth flat support sheet with a sorbent layer adhered to and covering one surface thereof is attached to one side of the frame with the sorbent layer facing the interior of the chamber. Next, a cover sheet is placed over the other side of the frame. The particular characteristics of the cover sheet are not critical. However, it would almost always be desirable to form the same from a substantially transparent material so that the progress of the chromatographic analysis could be visually observed. The chamber formed between the two sheets should be as thin as is practical so that the volume of the chamber will be small, whereby rapid equilibration will be achieved when the migrating solvent is released in the chamber to develop the chromatogram.

To render the device self-sufiicient for use in the field away from the laboratory, the migrating solvent is mounted in a capsule right in the chamber itself. Among suitable solvents from which to select for specific analyses are benzene, chloroform, alcohols, butanol-acetic acidwater, and propanol-ammonia. The capsule is provided with a weakened portion, tit, or plug which is connected to a wire or thread extending outside of the chamber so that by merely pulling the wire or thread the solvent can be released from the capsule and allowed to come into contact with the chromatogram sheet. For example, in one embodiment of the invention the capsule is mounted on a column attached to the frame with the weakened portion located at the bottom so that when the wire or thread is pulled solvent will fall to the bottom of the chamber. Preferably an absorbent pad is provided at the bottom of the chamber to prevent splashing of the solvent and to permit a more uniform movement of the solvent onto the sorbent layer of the chromatogram sheet.

Additionally, if desired, further provision may be made within the chamber to render the same completely selfsufiicient for field application. For example, a visualization reagent which reacts with colorless compounds after the chromatographic separation to render them visible may be included in the chamber. The visualization reagent may be incorporated in the same capsule as the migrating solvent, e.g. butanol-acetic acid-water containing 0.2% ninhydrin. Alternatively, the visualization reagent may be added in a second capsule or incorporated in the sorbent layer. Furthermore, means may be provided, if desired, for indicating or reducing the moisture level within the chamber.

To operate the apparatus of this invention, the sample to be tested is added to the sorbent layer by passing a hypodermic needle or syringe through a small hole in either the cover sheet (unless, of course, it is a hard material such as glass) or through from the back of the support sheet. Solvent is then introduced, and, after development, the chromatogram is peeled off and removed by suitable means such as by pulling a tab provided on the periphery of the support sheet extending outwardly away from the frame.

Thus, it is an object of this invention to provide an improved device for thin-layer chromatography which overcomes disadvantages of conventional apparatus known heretofore.

It is another object of this invention to provide a simplified apparatus for carrying out chromatographic separations in the field, away from laboratory facilities, special apparatus, or the like.

It is still another object of this invention to provide a completely self-contained unit for thin-layer chromatographic analysis in the field. It is still another object of this invention to provide a simplified and compact thin-layer chromatography apparatus which is so simple in design and low in cost that a single use followed by discarding of the apparatus would be practical.

It is still another object of this invention to provide an improved sandwich-type thin-layer chromatographic apparatus comprising a chamber formed between two sheets, a chromatogram sheet and a cover sheet, the sheets being separated by a spacing frame which frame together with the sheets forms a substantially enclosed chamber.

Other objects and the attendant advantages of the present invention will become apparent from the detailed description to follow together with the accompanying drawings which describe and illustrate a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a perspective view illustrating a chromatographic device in accordance with this invention.

FIG. 2 is a vertical sectional view taken along line 2-2 of FIG. 1.

FIG. 3 is a fragmentary vertical sectional view similar to FIG. 2 showing a modified arrangement for mounting the solvent capsule.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings there is shown in FIGS. 1 and 2 a chromatography apparatus including a frame 11. Although the frame may be of any convenient shape, in the preferred embodiment of the invention it is rectangular and includes a pair of side edges 12, a top 13 and a bottom 14. The frame may be formed of any suit able material which is inert with respect to the particular migrating solvent or to other chemicals to be used during the chromatographic analysis. Suitable materials for construction of the frame include solvent resistant plastics such as polyethylene, polypropylene, polyethylene terephthalate, Teflon, nylon, polycarbonate, polystyrene, and Lucite. The frame is preferably made of a thermoplastic material so that it can be heat-sealed or solvent-sealed together, and similarly sealed to the remainder of the apparatus to be described below.

A thin-layer chromatogram sheet 15 comprising a smooth fiat support sheet or backing 16 and a sorbent layer 17 is attached to the back edge of frame 11 to close off that side. If the backing 16 is of a thermoplastic material then the sheet 15 can be heat-sealed to the frame 11. Alternatively, a suitable bonding cement or glue 18 may be employed at the lines of contact between the sheet 15 and the frame 11. The sheet 15 may be marked at points 17a to indicate the spots where the sample material is to be placed. The sheet 15 also includes a tab 19 extending outwardly from the frame for peeling off and removing the chromatogram from the frame after development, for purposes of measurement, visualization, storage, etc. Of course, if desired, and if operating conditions permit, the backing 16 could also be a hard non-thermoplastic material such as glass.

A cover sheet 21, of corresponding geometric configuration to sheet 15, is attached to the front edge of frame 11 to act together with frame 11 and sheet 15 to form a substantially enclosed chamber. The cover sheet 21 should have certain characteristics in common with the frame, namely, resistance to the migrating solvent and to other chemicals used during the chromatographic analysis, and heat or solvent scalability for facilitating its connection to frame 11. Moreover, cover sheet 21 should be substantially transparent so that the chromatogram may be observed visually. Of course, if desired, the cover sheet could also be formed of a hard non-thermoplastic material such as glass. In this case cover sheet 21 would be attached to frame 11 by suitable bonding material 20.

There has been described above an arrangement which provides a substantially improved chamber for carrying out a chromatographic analysis. It is compact and far more convenient to use than chambers known heretofore.

A further important feature of the present invention is that the device may be constructed so as to include the migrating solvent, or other necessary chemical reagents, within the chamber, thereby rendering it completely self-sufficient and suitable for use in the field, such as in a doctors ofiice, crime laboratory, production areas, or other remote locations lacking extensive facilities.

A preferred arrangement for mounting the solvent within the chamber is shown in the drawings. A capsule 25 of thin glass or plastic having migrating solvent 26 contained therein is attached to a column 27 extending from the top 13 to the bottom 14 of frame 11. The capsule 25 includes a weakened portion, a tit, or a plug 28 connected by a thread or wire 29 through an aperture 30 in frame 11 to a tab 31. By simply pulling tab 31 and breaking the weakened portion or tit, or pulling out the plug, the capsule 25 can be opened to release the migrating solvent 26 onto the bottom 14 of the chamber. Alternatively, the solvent capsu e can be opened by squeezing through the sides of the chamber, or penetrating it with a needle from outside. An absorbent pad 35 can be provided on the bottom 14 of the chamber for receiving the solvent 26 in such a manner as to prevent splashing, and also to permit a more uniform migration of the solvent onto sorbent layer 17.

Within the spirit and scope of the invention numerous variations and modifications are possible. Some of these are shown in phantom lines in the drawings. For example, the chamber may also include means for mounting therein suitable visualization reagents (these may be liquids such as ninhydrin or gases such as ammonia or iodine vapor). The visualization reagent may be incorporated in the same capsule as the migrating solvent, or in a coated layer on the sorbent layer 17, or in a separate capsule such as capsule 40 shown in the drawings. Capsule 40 may be an aerosol spray bottle having a valve, or it may include a weakened portion, tit, or plug. A thread or wire 41 extending from the valve or other means through the frame 11 to a tab 42 is operated in a similar manner to thread or wire 29.

For controlling moisture content within the chamber, an indicator means such as commercially available indicating silica gel containing cobalt compounds of changeable color, shown in phantom lines as 45, can be included within the chamber. Also, desiccant material stronger than the adsorbent can be used to maintain dry conditions in the chamber.

Since the sorbent layer is within an enclosed chamber in the apparatus of this invention, it is possible to maintain the sorbent layer in an active condition for prolonged periods, thereby eliminating the usual procedure of activating or otherwise pretreating the sorbent layer immediately prior to use. Another advantage of the sealed chamber is that it acts as a protective enclosure for the sorbent which is highly active and would tend to pick up impurities if exposed to the air or to some packaging materials. A still further advantage stemming from the fact that the sorbent layer is within an enclosed chamber is that a standard or reference compound, prespotted on the sorbent layer, can be used for comparison with the samples.

In an alternate embodiment of the invention, as shown in FIG. 3, a solvent capsule 25 is attached to the frame 11 by bands of

adhesive tape

51, 52, or the like, which are secured between one of the side sheets 21 and the adjacent edges of the frame at top and bottom (or opposite sides). The bottom of the bottle 25' has a weakened portion, tit or plug 28' which can be broken or removed by pulling a wire or thread 29 extending through an opening in frame 11' to a tab.

The preferred embodiment of the invention described herein is operated as follows. The apparatus is first sealed together, with migrating solvent encapsulated therein, thereby forming a self-sustained sandwich-type chromatographic developing chamber. The sample mixture to be separated is then spotted on the marks 17a provided on the sorbent layer 17 by passing either a syringe or a hypodermic needle through sheet 15 or sheet 21. Alternatively, small holes can be formed in one sheet and then covered with adhesive tape which can later be pushed back to permit a syringe or needle to pass therethrough. After the samples have been placed on the spots 17a, and with the chamber in an upright position, the tab 31 is pulled to release the solvent 26 to fill the lower part of the chamber, splashing being prevented by absorbent pad 35 on the bottom 14 of the chamber. The solvent fills the lower part of the chamber and immediately begins to rise through the sorbent layer 17 by capillary action, carrying with it the components of the mixture to be separated. After separation has been completed, tab 19 is pulled to remove the chromatogram from the frame 11 for measurement, visualization, etc.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

I claim:

1. A device for conducting thin-layer chromatographic separation, comprising:

a smooth flat support sheet,

a thin chromatographically-active sorbent layer adhered to and covering one surface of said support sheet,

a cover sheet of corresponding geometrical configuration to said support sheet disposed with one surface thereof opposite said sorbent layer and in proximity thereto,

frame means secured to and spacing said support sheet and said cover sheet to form therewith a substantially enclosed chamber,

a capsule of migrating solvent mounted in said chamber, and

means operable from outside said chamber extending therein for opening said capsule and releasing said solvent, whereby said solvent is brought into contact with said sorbent layer to effect chromatographic separation.

2. A device as described in claim 1 wherein each of said support sheet, cover sheet and frame means is rectangular in shape.

3. A device as described in claim 1 wherein said support sheet includes a tab portion extending beyond said frame means for removing the chromatogram after development.

4. A device as described in claim 1 wherein said cover sheet is substantially transparent.

5. A device as described in claim 1 including a column within said chamber connected to said frame means, said capsule being mounted on said column.

6. A device as described in claim 1 including a strap for supporting said capsule passing over said capsule and extending in opposite directions therefrom, with the ends thereof being held between one of said sheets and said frame means.

7. A device as described in claim 1 including the absorbent pad on the bottom of said chamber for receiving said solvent after release from said capsule.

8. A device as described in claim 1 including means within said chamber for regulating the moisture content thereof.

9. A device as described in claim 8 wherein said means for regulating the moisture content within said chamber is a dessicant.

10. A device as described in claim 1 wherein said means for opening said capsule is a wire having one end thereof connected to said capsule and the other end thereof extending outside said chamber.

11. A device as described in claim 10, wherein said capsule includes a plug closing an opening therein, said plug being connected to said wire.

12. A device as described in claim 10 wherein said capsule includes a weakened portion to which said wire is connected.

13. A device as described in claim 1 including a visualization reagent within said chamber for effecting reaction with colorless compounds undergoing chromatographic separation to render them visible.

14. A device as described in claim 13 wherein said visualization reagent is incorporated within said capsule of migrating solvent.

15. A device as described in clai m13 wherein said visualization reagent is contained within a capsule which is separate to said capsule of migrating solvent and mounted within said chamber.

16. A device as described in claim 13 wherein said visualization reagent is incorporated within said sorbent layer.

References Cited UNITED STATES PATENTS 3,189,541 6/1965 Brenner.

3,449,083 6/ 1969 Pelick 232S3 FOREIGN PATENTS 1,370,780 7/1964 France.

JOSEPH SCOVRONEK, Primary Examiner S. MARANTZ, Assistant Examiner US. Cl. X.R. 73-611; 2l0198