US3413842A - Thin-layer chromatographic developing apparatus - Google Patents

Description

Dec. 3, 1968 J. c. HECKER 3,413,842

THIN-LAYER CHROMATOGRAPHIC DEVELOPING APPARATUS Filed May 6, 1966 Q I i9/l3 ,X ujflwjiwg? F/6.Z

JOHN C. HECKER INVENTOR.

ATTORNEY 3,413,842 THIN-LAYER CI-IROMATOGRAPHIC DEVELOPING APPARATUS John C. li-Iecker, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New York Filed May 6, 1966, Ser. No. 548,165 8 Claims. (Cl. 7361.1)

ABSTRACT OF THE DISCLOSURE Apparatus for the development of chromatographic sheets used in thin-layer chromatography including a tray which provides a well, integral therewith, for holding the developing liquid and for receiving one end of the chromatographic sheet. A cover is provided which fits tightly on the tray and holds the chromatographic sheet so that it is maintained in contact with a plurality of spaced protuberances, extending from either the tray or the cover, to prevent capillary flow of the developing liquid adjacent the chromatographic sheet.

The present invention relates to improved chromatographic developing apparatus for use with flexible, thinlayer chromatographic sheets.

Thin layer chromatography depends upon the flow of a liquid solvent in an absorbent sheet or layer having various substrates placed thereon which flow with the solvent, the individual substances flowing at different rates to provide a pattern which may be analyzed.

Recently, chromatographic sheets have been formed of a flexible material such as a polyester or other plastic sheet having a thin layer of absorbent thereon, as described in the pending US. application Ser. No. 450,362 assigned to the Eastman Kodak Company, as is also the present application. Such flexible chromatographic sheets are not sufliciently rigid to be used successfully without special provisions for their support, as by clamping them between rigid glass plates which are then dipped into solvent in a separate vessel. Suitable equipment for such support is described in United States Patent 3,318,451, also assigned to the Eastman Kodak Company. Such equipment has operated successfully, but is more complicated than is desirable for efficient laboratory operations, mainly because of the number of separate parts required. Moreover, the equipment must be operated with the sheet in a vertical position, which is not always the most desirable.

In accordance with the present invention there has been provided a novel chromatographic developing chamber of greater simplicity than the prior art which operates effectively with thin, flexible sheets. Moreover, my improved device is particularly advantageous because it can be operated in either a horizontal or vertical position, or tilted at an acute angle, as desired. These improvements are obtained while at the same time avoiding detrimental flooding which may occur when a chromatographic sheet is in such close contact with a supporting plate that flow occurs by capillary action.

My improved chamber comprises a shallow tray of glass or other inert material having an inside bottom surface, and having integral therewith an elongated narrow well which is deeper than the inside bottom surface for holding a supply of developing liquid solvent into which one end of a flexible chromatographic sheet is di ed.

A cover of similar material flts tightly on the top of the tray for providing an atmosphere predominantly saturated with solvent vapor; and the major portion of the chromatographic sheet, which protrudes from the well,

nited States Patent 0 lies loosely within the narrow space between the cover and the inside bottom surface.

In order to prevent capillary travel of solvent, which would adversely affect the analysis, either the cover or the inside bottom surface of the tray is provided with a plurality of spaced protuberances of slightly lesser height than the distance between the bottom surface and the cover to provide space for the sheet, and to hold the sheet sufiiciently firmly in position while at the same time avoiding capillary action by preventing areas of the flat sheet from lying on flat areas of the chamber. In operation the coated side of the sheet faces the protuberances.

The novel apparatus will be described more in detail hereinafter with reference to the accompanying drawings wherein:

FIG. 1 is a perspective view showing my novel chromatographic developing chamber with the cover removed, but in position to be replaced;

FIG. 2 is a vertical, sectional view taken along the line 22 of FIG. 1; and

FIG. 3 is a fragmentary vertical sectional view of another embodiment which is so designed as to be operable in any position between horizontal and vertical.

Referring to FIG. 1, the chromatographic developing chamber comprises a tray 11 having an inside bottom surface 13 recessed below the rim 15 of the tray by a distance slightly greater than the thickness of the flexible chromatographic sheets that are to be developed.

The bottom surface 13 extends over the major portion of the tray, and at one end there is an elongated narrow well 17 which is considerably deeper than the bottom surface 13 for holding a supply of developing solvent, and into which one end 19 of a chromatographic sheet 21 is intended to dip as shown in FIG. 2.

To assure that the chromatographic sheet will be held firmly in position, the bottom surface of the well 17 is provided with a long, narrow slot 23 which terminates at its ends a short distance before the ends of the well and is adapted to receive the extreme end 25 of the sheet.

Advantageously the rim 15 of the tray lies in a single plane, and is adapted to receive the cover 27 so that an atmosphere saturated with solvent vapor is maintained. This is accomplished by providing the cover 27 with a peripheral surface which is also a single plane, both the surface of the cover and the tray being ground or otherwise made sufficiently smooth to provide a tight joint.

The sheet 21 bends from its end 25 arcuately to a horizontal position, and the major portion of its surface lies within the space between the bottom surface 13 of the tray and the cover 27. Usually the coated surface of the chromatographic sheet 21, through which the solvent is to travel, faces downwardly as seen in FIG. 2; and when this is the case, if the bottom surface of the sheet 21 were to lie in contact with the bottom surface 13 of the tray over any substantial area, capillary action of solvent liquid might occur and adversely affect the analytical results. In order to avoid this, the surface 13 is provided with a series of protuberances in the form of a series of ridges 29 which extend transversely across the tray and are spaced longitudinally from one another sufficiently to break the continuity of any surface contact and thus prevent capillary action. To avoid damaging the thin layer on the sheet 21, the ridges are rounded and smooth. Instead of ridges, pimples can be used.

Instead of providing the protuberances on the tray, as described above, the bottom surface 13 can be left smooth, and the ridges or other protuberances can be provided on the bottom surface of the cover 27, in which case the chromatographic sheet is employed with the thin adsorbent layer up, rather than down.

The apparatus described in detail above is simple in construction because it involves only the combination of two elements, the cover, and the tray with a solvent well integral therewith. It is particularly advantageous to use because it can be laid in the horizontal position without requiring supporting stands or clamping devices. Moreover, a completely enclosed developing space is provided which avoids the egress of solvent vapor from the apparatus, and eliminates solvent travel by capillary action.

FIG. 3 shows an embodiment of my invention which is designed to be operated either in a horizontal position, or at any angle to the horizontal up to 90. The principal difference over FIGS. 1 and 2 is the provision of a lip 33 which projects across the top of well 17' far enough so that when the tray is positioned vertically on its end 35 the liquid is still retained in the well to feed the chromatographic sheet.

Several spring clips 37 are required to hold cover 27' tightly in place on the tray 11'.

Alternatively, when downward flow of solvent is desired, the lip 33 can be provided on the opposite side of the well. Then the tray can be stood on the end opposite end 35, and the liquid will be held in the well to feed the chromatographic sheet.

This construction, and the upright positioning of the apparatus are especially advantageous to permit the analyst to observe the progress of an analysis from a distance while he is doing other work in the laboratory.

In another embodiment (not shown), the well 17 is located centrally of the tray 11, thus permitting two sheets to be developed at once from the same pool of solvent by positioning their ends in the well and extending the sheets in opposite directions across the tray.

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

I claim:

1. A chromatographic developing chamber for a chromatographic sheet, comprising a tray of generally rectangular confifuration having a peripheral rim and a surface bounded by said rim which serves as an inside surface of the chamber, said tray having an elongated transversely extending well therein for holding a supply of developing liquid and for receiving an end of such chromatographic sheet, and a cover adapted to fit on said rim in spaced relation to said surface for receiving the chromatographic sheet therebetween, at least one of said cover and said tray having a plurality of spaced protuberances arranged to engage the chomatographic sheet and to space it from contact therewith, said protuberances being of a height which is less than the distance between said surface and said cover when said cover is in position on said tray so as to provide space therebetween for the chromatographic sheet.

2. A chromatographic developing chamber in accordance with claim 1 wherein said rim lies in a single plane and said cover has a peripheral surface which also lies in a single plane.

3. A chromatographic developing chamber in accordance with claim 1 wherein said protuberances comprise a series of continuous transversely extending spaced ridges which are parallel to said well.

4. A chromatographic developing chamber in accordance with claim 1 wherein said protuberances are on said tray.

-5. A chromatographic developing chamber in accordance with claim 3 wherein said continuous spaced ridges are on said tray.

6. A chromatographic developing chamber in accordance with claim 1 wherein said tray includes a long narrow slot in the bottom of said well for receiving the end of the chromatographic sheet to hold it in position.

7. A chromatographic developing chamber in accordance with claim 6 wherein the ends of said slot are spaced a short distance from the corresponding ends of said well.

8. A chromatographic developing chamber in accordance with claim 1 wherein said tray includes a lip projecting partly across said well for retaining liquid in said well when said chamber is positioned vertically.

References Cited UNITED STATES PATENTS 3,189,541 6/1965 Brenner et al. 73--61.l XR 3,318,451 5/ 1967 Przybylowicz et al.

OTHER REFERENCES Davies: A Simple Saturation Chamber for Thin Layer Chromatography, J. Chrom. 10 (1963), pp. 518-521.

S. CLEMENT SWISHER, Acting Primary Examiner.

JOSEPH W. ROSKOS, Assistant Examiner.

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