BACKGROUND OF THE INVENTION The invention relates to an apparatus and method for improving the-speed and efficiency in performing thin layer chromatography (TLC) tests. Thin layer chromatography, one of the most standard lahoraton, techniques, is a solid-liquid partitioning technique used in chemical analysis. It is a micro-scale technique since only micrograms of material are needed to perform the analysis. A thin layer chromatography plate consists of a thin layer of adsorbent tiiatefial {stationary phase) coated on a backing support. Typically, the support is, but is not limited to, a glass plate and the adsorbent material is, but is not limited to, a silica/silicate material. When the thin layer plate is partially-submerged in a liquid (mobile phase), the liquid ascends the adsorbent by capillary action. By placing a small spot of a solution containing two compounds near the base of the thin layer plate, yet not immersed in the solvent, the ascending liquid carries the sample and partitions the sample between the adsorbent stationary phase and the liquid mobile phase (commonly referred to-as developing), After development, the p ! ate can be visualized and the distance a given compound travels with respect to the distance the solvent travels is referred to as the compounds Rf value and is expressed as a ratio. The Rf value is determined by a number of factors, namely the chemical-structure of the compound and its interactions with me prescribed stationary and mobile phases. Changing the composition of either the stationary phase compound or mobile phase solvent can have dramatic effects on not only how far the sample travels with respect to the solvent front (Rf), but how tightly the compound travels together (the-spot-size and-shape).

Different compounds have different interactions with the prescribed mobile and stationary phases and have a unique Rf of their own. Hence, thin layer chromatography is useful in determining the number of compounds in a given mixture. If the compounds in the mixture have very different chemical structures and the mobile/stationary phases are chosen properly. upon elution (development) the compounds will separate into their own spots with visible Rf differences between the spots. However, if the compounds have very similar chemical structure and/or the mobile/stationary phases are chosen poorly, the compounds may barely separate, if at all.

When ascertaining the chemical purity of a sample by TLC, the spot shape or the Rf difference between spots is not that crucial as long as all of the components of the mixture can be visualized. However, when one wants to physically separate the components of the mixture, me spot shape and the Rf difference between spats are crucial criteria when transferring what has been learned by TLC to the more macro- scale (mg-Kg) separation technique of column chromatography.

Column chromatography consists of a column, usually glass, a mobile phase, and a solid phase just as in thin layer chromatography. The adsorbent is packed into the column and the sample is loaded on top of the adsorbent. The mobile phase is then applied to the top of the column and flows through the column by either gravity or slight positive pressure. As in TLC, the column chromatography sample is partitioned between the mobile and stationary phases and depending upon the chemical structure of thecompound, and theconsistency of themobtle and statton*ry phases, thecompound traverses down the column in a band. When a mixture of compounds is applied to the top of the column, and the proper mobile and stationary phases are chosen, as the solvent flows through the column the compounds separate into bands which can be isolated into pure compounds by collecting the bands as theyelute out of the bottom of the column, commonly referred to as collecting fractions. When the consistency of these fractions is to be ascertained, one puts a spot from each fraction on a TLC plate and elutes (develops) with the same mobile and stationary phases as were run in the column. The factors that contribute to how well the compounds separate, arc the volume of the fractions taken, the how rate of the mobile phase, and most dramatically, the distance between the edges of the bands which is determined by the consistency of

the mobile stationary phases. When the distance (between band edges) is large or when the bands are narrow, good separation can be achieved.

Fractions 1-3 (figure not shown) can be combined and contain only pure compound A, fractions 4-7 (figure not shown) can be combined and contain only pure compound B, fractions 8-9 (figure not shown) can be combined and contain only pure compound C, and fractions 10-11 (figure not shown) can be combined and contain only pure compound D (Once compounds are pure, their structure can he elucidated by other spectroscopic means). However, when the distance (between band edges) is small or when the bandwidths are large, there can be a good amount of overlap in the fractions, such that only a few fractions contain pure compound. The other fractions either have to be thrown out, or resubmitted to another column chromatographic separation, which makes structure elucidation cumbersome if not impossible. This outcome is very undesirable from a synthetic-standpoint, because it results in a loss of chemical yield and purity, and also a large loss of time if the mixtures have to be resubmitted to another column chromatographic separation. In all, poor separation is a very costly outcome.

The secret to separating mixtures of compounds using column ehromatography rests in the ability to maximize the distance between bands and also minimize the width of the bands. The two greatest factors that influence this separation are the consistency of the mobile and stationary phases. Since the typical number of stationary phases is limited to typically three or four substances, the chemist has at his disposa many pure mobile phases and an unlimited number of solvent combinations. However, one skilled in the art learns to get a feel of how to limit this number through trial and error and also prior experience. By testing a small number of solvents or combinations on TLC plates, using trial and error and experience, one can invest a tremendous amount of time trying to find an adequate mobile phase, since this is usually done in a linear step-wise non- scientific manner. This method often works, but this limited exploration and personal bias often lead to a solvent system that gives non-optimal separation between spots or largespot diameters, which when transferred to a column chromatographic reparation often results in band overlap which reduces chemical purity and yield. This old method as previously stated, is extremely undesirable especially if the compound being purified is extremely expensive and any loss of yield or purity is a loss of money.

OBJECTS OF THE INVENTION It is therefore an object of the present invention to provide an apparatus and method for performing thin-layer chromatography testing that allows multiple tests to be conducted simultaneously, using a grid of varying solvents and varying concentrations.

It is another object of the present invention to allow chromatography testing of an unknown material using less of the material. Preliminary identification of the material using thin-layer chromatography will save time and money before proceeding to column chromatography testing.

SUMMARY OF THE INVENTION Accordingly, the invention consists of an apparatus and method for using same, that, e. optimises mobile phase conditions for a given stationary phase TLC plate (smallest spot sizes, greatest Rf differences between spots, and greatest solubility).

When the optimized conditions arc translate to column chromatography, all other variables being considered equal (flow rate, amount of stationary phase. and fraction size), this will lead to the narrowest bands and/or greatest distance between bands that can be achieved with the prescribed stationary phase, hence the best separation that can be achieved. The apparatus consists of an n x n array of TLC developing chambers, typically test tubes, and a method of running multiple simultaneous TLC plates with multiple mobile phases. The chambers are arranged in a grid of rows and columns to supply the greatest organization. The preferred embodiment for the apparatus is a 10 column x 10 row grid of developing chambers. This is preferred because of the ability to vary the concentrations in increments of 10 percent.

Thus, the invention provides apparatus for conducting multiple simultaneous thin layer chromatographic processes, including an array of multiple thin layer chromatography chambers, the array being held by one or more supports and each chromatography chamber comprising a thin layer chromatography plate. The array can optionally include n x n chromatography chambers, wherein n is an integer ranging from 5 to 10. Although in the following description the term"chamber"will be used, it should be understood by those skilled in the art that this term encompasses any means

defining a space or cavity capable of receiving a solvent, such as a container, a vessel or a receptacle.

Each thin layer chromatography chamber is held in a fixed array by a top and bottom support. For example, each thin layer chromatography chamber is positioned in a receiving indentation in a supporting base and is held in place by an upper plate.

Accordingly, a broad embodiment of the invention includes an array of receptacles, each receptacle being receivable of chromatographic fluid, support means for supporting the receptacles to enable the chromatographic analysis, and retaining means coupled to the support means for retaining a plurality of thin layer chromatographic plates. The retaining means enable each plate to be inserted into and removed from a respective receptacle while the receptacles are supporte by the support means. The array may comprises n x n receptacles, whereby n is an integer ranging from 5 to 10. The support means can comprise a top plate and a supporting base whereby the receptacles are at least partially situated between the top plate and the supporting base. The top plate can comprise a plurality of apertures whereby each receptacle is insertable into a respective aperture. The supporting base can include a plurality of receiving indentations or cups whereby each receptacle rests in a respective indentation. In use, to place the receptacles in the apparatus, the receptacles are inserted through the apertures in the top plate until the bottoms of the receptacles rest in the indentations in the supporting base.

The retaining means may comprise a plurality of plungers, each coupled to a respective chromatographic plate, and plunger blocks whereby each plunger is coupled to one of the plunger blocks. The plunger blocks rest on the top plate, when present, to thereby support the plungers on the top plate. The retaining means may further comprise mounting plates arranged on the plunger blocks. Each plunger is movable within the coupled plunger block to allow the plate to be raised or lowered relative to the level of chromatographic fluid in the receptacle The retaining means may further comprise a plate holding frame coupling each plunger and a respective plate. The plate holding frame holds the plate by a compression fit or with a spring loaded clamp.

The invention also provides methods for conducting multiple liquid chromatographic assays using the provided apparatus. The chromatographic assays can

be performed substantially simultaneously if so desired. Broadly, the method includes the steps of (a) spotting one or more samples of interest onto multiple thin layer chromatography plates, (b) filling chromatography chambers with a suitable amount of a chromatography solvent, (c) inserting the plates into respective chambers and allowing the processes to continue for a sufficient time period for sample separation to occur, (d) visualizing or detecting the separated samples.

The chambers may be arranged in an n x n array and the apparatus described may be used to perfonn the method Furthermore, at least one parameter may be varied systematically between developing chambers, e. g., the solvent composition of the mobile phase, the composition of the solid phase, and the concentration of the analyte.

Also disclosed herein is a thin layer chromatography assembly comprising means defining a chamber having an open upper end and receivable of a chromatographic fluid, a plunger block for closing the upper end of the chamber, a movable plunger coupled to the plunger block and having a first accessible end exterior of the chamber and a second end positionable in the chamber, a plate holding frame coupled to the second end of the plunger, and a thin layer chromatography plate retained by the plate holding frame. This assembly may be used in the apparatus and method described above.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated into and form a part of the specification, illustrate several embodiments of the present invention and, together with the following description, serve to explain the principles of the invention. The drawings are for the purpose of illustrating preferred embodiments of the invention only and are not to be construed as limiting the inventions.

Figure I is a perspective of a five-by-five grid of the invention.

Figure 2 is a drawing of a TLC developing chamber.

Figures 3A, 3B, 3C and 3D are a series of exploded views of the invention.

Figure 4 is a side view of a five-wide grid of the invention.

Figure 5 is a top view of a five-by-five grid of the invention.

Figure 6 is a side view of a single test tube with cap and plunger.

Figure 7 is a perspective view of the invention with a five-by-five grid of TLC tubes.

REFERENCE NUMERALS IN THE DRAWINGS 1. Plunger 2. Top plate 3. Test tube 4. Thin layer chromatography plate 5. Base plate 6. Mounting plate 7. Plunger block 8. Plate holding clip 9. Plate holding frame 10. Support DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The apparatus is constructed of a base 5 with cups (also referred to a receiving indentations herein) for holding the developing chambers 3. As shown in Figure 5. the base 5 is connected to supports 10 for holding a top plate 2 which has holes for inserting and holding the developing chambers 3. A plunger 1 includes a manually accessible knob at an upper end and a shaft which extends through a plunger block 7 to enable a lower end of the plunger 1 to engage with the TLC plate 4 (see FIG. 3A-3D).

Plunger block 7 rests on the top plate 2 and is coupled to the plunger I so that by lifting and lower the plunger 1, e. g., via the knob, the plunger block 7 (and the TLC plate 4) is

also lifted and lowered. However, the plunger 1 can also be moved relative to the level of fluid in the chambers 3, i. e., slidable or movable within the plunger block 7, possibly be holding the plunger block 7 against the top plate 2 while raising or lowering the plunger 1. A mounting plate 6 holds the plunger block 7 and the plunger 1. The end of the plunger 1 is connected to a plate holding clip 8. The plate holding clip can be a compression fit, or a spring loaded clamp. An electrical alligator clip works adequately.

The plate holding clip 8 is also attached to a plate holding frame 9 which fits over the edges of a TLC plate 4. The TLC plate 4 is suspended in the mobile phase at the bottom of the developing chamber 3. The plunger 1 may also allow the plate 4 to be raised or lowered relative to the solvent level.

More particularly, it can be seen in FIG. 1 that there are five rows of plunger blocks 7 in the illustrated embodiment, each row being separate and uncoupled from the others. In use, each plunger block 7 has an associated plunger 1 and mounting plate 6 and is coupled to a plate holding clip 8, a plate holder frame 9 and a TLC plate 4. By providing multiple, separate rows of plunger blocks as in the illustrated embodiment, it is possible to raise and lower each of the rows of plunger blocks without interference from the other rows of plunger blocks. The demarcation between the rows of plunger blocks is shown most clearly in FIG. 4, a side view of the invention. Further as shown in FIGS 1,4 and 7, the top plate 2 and base plate 5 have substantially the same dimensions.

Using the apparatus of the invention allows the user to perform multiple tests simultaneously in a scientific manner. A 10 x 10 grid of developing chambers would allow rapid testing of 100 different tests of varying samples, adsorbents (stationary phases), and solvent combinations (mobile phases). The array of results will indicate the best way to proceed towards the purification of the sample, whether that be continued TLC testing to find proper conditions or the finding of proper conditions which can be transferred to column chromatography. Comparison of the number of spots, the Rf differences between spots, the shape of the spots, and the solubility of the sample in the prescribed mobile phase will aid in the evaluation.

Many changes, modifications, variations and other uses and applications of the subject invention will become apparent to those skilled in the art after considering this specification and the accompanying drawings which disclose the preferred embodiments thereof. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the following claims.