US3327857A - Chromatography apparatus - Google Patents

Description

June 27, 1967 R H KOPP CHROMATOGRAPHY APPARATUS Filed Oct. 12, 1966 FIG.3

RM WWW EL United States Patent M:

3,327,857 CHROMATOGRAPHY APPARATUS I Reiner H. Kopp, Huntington, N.Y., assignor to Brinkmann Instruments, Inc, Westbury, N.Y., a corporation of New York Filed Get. 12, 1966, Ser. No. 586,245 9 Claims. (Cl. 210-198) This invention relates to chromatography apparatus. More particularly, it relates to apparatus for positioning chromatography sheets for effecting the migration of materials under analysis from a solvent reservoir into the sheet.

The art of chromatography is a long-established and widely used tool in biological and chemical laboratories for analysis of compounds. Broadly, it is based on the migration of solvents carrying the molecules to be analyzed through a porous medium, such as a diatomaceous earth layer or a fiber sheet, so that the molecules become disposed at relative positions in the sheet which are indicative of their nature or identity. Typically, the examination of the layer is made at the conclusion of a predetermined time interval or continuous flow can be effected. The visual display of the dispersed molecules can be brought about in various ways, among the commonest of which is exposure to ultraviolet radiation. The apparatus includes in its least complex form, a solvent reservoir and some means of supporting the porous medium for the passage or migration of the solvent through it.

Chromatography apparatus tends to be fragile. Frequently the solvent in the reservoir is continuously exposed to the open air so that costly solvents are lost by evaporation. Also, contamination occurs from atmospheric borne moisture and other pollutants. Attempts to seal the reservoir have resulted in relatively costly, cumbersome devices which are difficult to clean.

Accordingly, it is an object of the present invention to provide a new and improved chromatography apparatus which overcomes the various disadvantages of many present-day devices by effectively sealing the solvent reservoir from the atmosphere so that contamination is prevented and evaporation losses are minimized.

Another object of the present invention is to provide a new and improved chromatography apparatus in which optimized solvent-flow through the display medium is effected while at the same time providing effective sealing against atmospheric exposure.

Still another object of the invention is to provide chromatography apparatus which is robust in construction and readily cleaned and decontaminated by conventional laboratory cleaners.

Still another object of the invention is to provide improved chromatography apparatus in which accelerated solvent flow through the display medium can be effected by a supplemental evaporator disposed at the edge remote from the reservoir.

Still another object of the invention is to provide improved chromatography apparatus in which carrier plates of various thicknesses can be readily accommodated.

Still another object of the invention is to provide chromatography apparatus having a solvent and specimen reservoir which is sealed from the atmosphere but to which additional solvents can be added automatically as needed to maintain the reservoir level throughout a complete operating cycle without moving, displacing, or in any way interfering with the continuing operation of the migrating liquid in the medium which constitutes the chromatographic layer or sheet.

In accordance with the present invention, there is provided chromatography apparatus includin as an integrated unit, a reservoir, or trough, for containing solvents 3,327,8 5? Patented June 27, 1967 for transporting and specimen cells to be analyzed and a support for the chromatographic medium for suspending the lower edge thereof in the reservoir. The reservoir includes a partial cover portion overhanging the reservoir, but spaced a precise distance from the back wall to define a slot through which a portion of the chromatographic medium and part of its support are immersed in the solvent. To this end the medium is disposed between a carrier plate and a cover plate spaced apart to define a shallow chamber for the display portion of the medium. The carrier and cover plates are normally offset along their planes so that the bottom edge of the cover plate bears on a sealing lip formed on the cover of the reservoir and the carrier plate, together with the lower edge of the chromatographic medium, extends downwardly into the fluid without touching the bottom of the reservoir.

The rear or carrier plate bears slidably on a support, preferably taking the form of an inclined plane, the surface of which has a low coefficient of friction. The angle of this support is preferably optimized in the range of 40 to 50 degrees so that a substantial component of the weight of the carrier plate assembly bears on the sealing lip. The upper edge of the carrier plate assembly extends beyond the upper edge of the carrier to provide a hanging space for an evaporating sheet which can be brought into contact with the chromatographic medium. In this fashion large amounts of solvent which have completed the migration in the medium can be carried off to atmosphere, suitably vented as conditions might require. In the event it is desired to add liquid to the reservoir during any given analysis, there is provided, in accordance with the present invention, an opening, norm-ally plugged, in the upper edge of the reservoir into which can be inserted a suitable solvent container inverted to form a self-regulating fountain.

The above and other features and objects of the present invention will be readily apparent having reference to the following specification taken in conjunction with the accompanying drawing in which:

FIGURE 1 is a view in perspective showing the front and one side of chromatography apparatus with the carrier plates for the chromatography sheet removed;

FIGURE 2 is a view in vertical section of the apparatus in FIGURE 1 taken on the line 22 looking in the direction of the arrows but showing also the chromatography sheet and its carrier plates; and

FIGURE 3 is a view in transverse section in enlarged scale taken on the line of 33 of FIGURE 2 looking in the direction of the arrows.

Referring to the drawing, the invention iis llustrated as embodied in chromatography apparatus including a reservoir portion 10 and, formed integrally therewith, a plate carrier or support including an inclined surface 11 and a supporting leg 12. The reservoir includes an upper cover portion 13 carrying an inclined sealing lip 14 extending the full length of the reservoir. The rearward edge 14a of the sealing lip 14 is spaced a precisely predetermined distance, such for example as 8 mm., from the proximate portion of the inclined surface 11 (best seen in FIGURE 2) to define a channel. The sealing lip 14 is disposed in a plane generally perpendicular to the plane of the inclined surface 11. The rear wall 15 of the reservoir merges into the inclined surface 11 in a precisely formed bend 16 which is spaced upwardly with respect to the lower edge 14a of the sealing lip 14. End pieces 17 and 18 complete the reservoir.

The cover portion 13 includes an inclined forward wall portion 19 which carries a filler pipe 20, the upper portion of which is squared off horizontally, and the lower portion of which terminates within the reservoir space at the fluid level. The filling pipe 20 is normally closed by a plug 20a (FIGURE 1) but is illustrated in FIGURE 2 as carrying a supplemental liquid source in the form of an inverted, closed container 21 having a discharge spout 21a at its lower end which fits concentrically within the tiller pipe 20. As the liquid level in the reservoir 10 falls, air will be admitted into the container 21 and liquid will gravitate into the reservoir until the level reaches the lower edge of the filler pipe 20 to arrest the flow.

Resting on the inclined surface 11 is a chromatography plate means or mounting assembly means indicated generally by the numeral 22 for carrying a chromatography medium 23 which can take the form of an independent sheet between carrier and cover plates 24 and 25 or, as is most often the case, of a thin layer deposited as a film on the carrier plate 24. The carrier plate 24 can be formed of relatively thin glass such as 1 to mm., and the front or cover plate 25, of relatively thicker glass such as /2 inch glass plate, with the two opposed surfaces 24a and 25a, respectively, being spaced apart to define a shallow chamber within which the chromatographic medium 23 is disposed. The two plates 24 and 25 are held in spaced-apart relationship to define the internal chamber 7 by means of side edge spacers 26 and 27 and, if used, an upper edge spacer. These spacers can take the form, as best seen in FIGURE 3, of T elements formed of suitably stable material, such as plastic, which is held to precise dimensions and which is inert to most solvents and chemicals. A spacer of 2 mm. thickness is useful in the practice of the present invention.

The two plates 24 and are sandwiched together across the spacers and held in relatively fixed positions by means of a clamp 29. The lower, or depending, edge of the plate 24 extends beyond the corresponding edge of the plate 25 so that it projects into the liquid L contained within the reservoir it while the lower edge of the plate 25 rests on the sealing lip 14. The lower edge of the plate 24 is spaced a small distance from the bot-tom of the reservoir so the vertical component of weight of the assembly 22 which is not carried by the inclined surface 11 is carried by the sealing lip 14. The chromatographic medium 23 extends approximately to the lower edge of the plate 24 so that it is immersed in the liquid. In this fashion, the entire normally open channel at the top of the reservoir between the cover portion 13 and the rear wall 15 is effectively sealed by the assembly.

The inclined surface 11 is preferably coated with a stable material having a low coefficient of friction such as Teflonso that a maximum downward weight component of the chromatography plate means or mounting assembly bears on the sealing lip 14, giving rise to an efiicient seal along the entire length of the lower edge of the plate 25 and along the entire lower surface of the lower plate 24 where it engages the inclined surface 11. The only exposure of the reservoir to the atmosphere will therefore occur in the small clearance spaces at the side edges of the mounting assembly means 22 where it enters the reservoir. The liquid L within the reservoir will, in accordance with well-known principles, migrate due to capillary action into the layer 23, passing along its length until the operation is terminated or until it reaches the upper, or remote, edge. The specimen or sample under study is placed on the chromatographic layer or sheet before it is inserted into the chamber and in the spaced or area above the liquid level.

The inclined surface 11 is arranged at a predetermined angle which is optimized to insure maximum developer solvent flow during analysis while at the same time effecting eflicient sealing to close the channel between the rear wall 15 of the reservoir and the lower edge 14a! of the sealing lip. In the illustrated embodiment of the invention, the inclined surface is disposed at an angle of 45 degrees. Effective sealing without signficant loss of liquid movement through the sheet is obtainable over angles in the range of to 50 degrees.

Two different developing techniques may be practiced with the apparatus of the present invention. In one case the solvent is wicked by capillary action through the thin layer and the amount of development is interruped as soon as the solvent reaches a certain height, normally 10 cm. from the application point of the sample. In the other case the separation is not interrupted and after the solvent front reaches the upper edge of the thin layer, it is drawn off in order to accomplish a continuous solvent flow separation. In the latter case, the upper sealing T element can be removed and an evaporating sheet 30, such as filter paper inserted to form a wick to draw off the solvent. The portion 30a of the filter paper which extends into the shallow chamber between the plates 24 and 25 is in engagement with the upper or remote edge of the medium 23 so that solvents which reach that region will be picked up by the filter paper and carried out of the chamber to be evaporated in the atmosphere from the large, depending portion 30b which hangs like a curtain at the rear of the assembly for maximum atmospheric exposure. In cases in which less volatile liquids are used, a collection trough 31 can be placed below the lower edge of the depending sheet to accumulate liquid which drips therefrom.

While the invention has been described above having reference to perfected embodiments thereof, it will be understood that it can take other forms and arrangements within the scope of the invention. Thus, for example, an electrical voltage can be impressed across the horizontal axis of the paper by incorporating electrode in the side spacers 26 and 27. The invention should not, thereof, be regarded as limited except as defined in the following claims.

I claim:

1. Chromatography apparatus comprising a liquid reservoir including front, side and rear walls and an overhanging cover portion carried by and merging with the side and front portions and having a rearwardly, downwardly inclined lip spaced a predetermined distance from the rear wall, and an inclined support including a sealing surface disposed perpendicular to the plane of the lip of the cover portion, said inclined support being adapted to carry chromatography plate means resting sildably on the sealing surface with its lower edge resting on the lip of the cover portion in sealing relationship whereby the chromatography plate means fills the space between the lip of the cover portion and the rear wall of the reservoir, the weight of the chromotography plate means being distributed between the lip of the cover portion and the inclined surface of the support to effect seals against the escape of gases from the reservoir.

2. Chromatography apparatus comprising mean including front, side, bottom and rear walls defining a liquid reservoir, an inclined support merging into the upper edge of the rear wall of the reservoir and having a sealing surface inclining upwardly therefrom at an angle, a cover portion attached to the front wall of the reservoir and having a rearwardly disposed downwardly inclined lip spaced a predetermined distance from the extended plane of the sealing surface of the inclined support and disposed in a plane substantially perpendicular to said plane, and chromatography plate means adapted to rest slidably in an inclined position on the sealing surface and to bear by means of its front lower edge on said lip, whereby the sealing relationship between the plate means and the lip and the plate means and the sealing surface of the support substantially seals the reservoir against exposure to the atmosphere, with the plate filling the gap between the lip and the rear wall of the reservoir and with the weight of the plate means being distributed between the lip and the sealing surface of the inclined support.

3. Apparatus as set forth in claim 2, said chromatography plate means comprising at least a pair of upper and lower plate members carrying a chromatography medium therebetween and means to clamp the upper and lower plates together in offset relationship with the lowermost plate extending, together with the chromatography medium, for a predetermined distance below the lower edge of the upper plate, said predetermined distance being slightly les than the distance from said sealing lip of the cover portion to the bottom wall of the reservoir as measured in the plane of said sealing surface.

4. Apparatus as set forth in claim 3, said sealing surface merging into the rear wall of the reservoir in a horizontal line which is disposed above the edge of the lip of the cover portion.

5. Apparatus as set forth in claim 3, said chromatography plate means comprising a pair of glass plates, and spacer means to hold the plates in spaced-apart relationship to define a shallow chamber to receive the chromatography medium and to seal the edges of the plate means.

6. Apparatus as set forth in claim 3, the upper edge of said plate means extending beyond said inclined support, and an evaporating sheet hung from the upper edge of the plate means in contact with the chromatography medium.

7. Apparatus as set forth in claim 6, including a supporting leg depending from the upper edge of the inclined support, said supporting leg, inclined support and supporting surface, reservoir wall means and cover portion all being formed of a single piece of sheet material bent on horizontal lines.

8. Apparatus as set forth in claim 3, including a supporting means for holding the inclined support at an angle with the horizontal Within the range of approximately 40 to 50.

9. Apparatus as set forth in claim 3, including a filling tube for the reservoir in said cover portion extending downward into the reservoir for a predetermined distance to establish a liquid level therein.

References Cited Davies, B. H.: A simple saturation chamber for thinlayer chromatography, Journal of Chromatography, vol. 10, 1963, pages 518-521.

REUBEN FRIEDMAN, Primary Examiner.

I. DE CESARE, Assistant Examiner.

Claims (1)

1. CHROMATOGRAPHY APPARATUS COMPRISING A LIQUID RESERVOIR INCLUDING FRONT, SIDE AND REAR WALLS AND AN OVERHANGING COVER PORTION CARRIED BY AND MERGING WITH THE SIDE AND FRONT PORTIONS AND HAVING A REARWARDLY, DOWNWARDLY INCLINED LIP SPACED A PREDETERMINED DISTANCE FROM THE REAR WALL, AND AN INCLINED SUPPORT INCLUDING A SEALING SURFACE DISPOSED PERPENDICULAR TO THE PLANE OF THE LIP OF THE COVER PORTION, SAID INCLINED SUPPORT BEING ADAPTED TO CARRY CHROMATOGRAPHY PLATE MEANS RESTING SLIDABLY ON THE SEALING SURFACE WITH ITS LOWER EDGE RESTING ON THE LIP OF THE COVER PORTION IN SEALING RELATIONSHIP WHEREBY THE CHROMATOGRAPHY PLATE MEANS FILLS THE SPACE BETWEEN THE LIP OF THE COVER PORTION AND THE REAR WALL OF THE RESERVOIR, THE WEIGHT OF THE CHROMATOGRAPHY PLATE MEANS BEING DISTRIBUTED BETWEEN THE LIP OF THE COVER PORTION AND THE INCLINED SURFACE OF THE SUPPORT TO EFFECT SEALS AGAINST THE ESCAPE OF GASES FROM THE RESERVOIR.

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