THE METHOD OF LIQUID DELIVERY TO THE ADSORBENT LAYER

Abstract

(EN) In the chromatographic chamber (3), to which the tip (11) enters from below. The tip (11) serves as the end of separate supply lines (5a, 5b, 5c . . . 5x), and each supply line (5a, 5b, 5c . . . 5x) is intended to deliver a separate eluent component. The first supply line (5a) comprises the first reservoir (6a) connected to the first pump (7a), to which the first flexible tube (8a) is connected terminated with the rigid tube (9a). The tip (11) is the first turning point (21) and then, with the use of the three-dimensional machine (2), it is passed along the line to the second turning point (22) and back again, while the individual components are pumped with variable efficiency controlled by the computer (20). This results in a quantitative and qualitative composition in time. At the same time, the position of the moving front is registered with the digital camera (19), and the signals of the eluent front migration distance are registered by the computer (20), and based on this information, the pumps (7a, 7b . . . 7x) that the individual components of the eluent are controlled accordingly. After reaching the final migration of the eluent front, the delivery of the components is stopped, and then the plate (18) is removed from the chromatographic chamber (3) and dried under the hood. As a result, the developed chromatogram is obtained. (19), and the signals of the eluent front migration distance are registered by the computer (20), and based on this information, the pumps (7a, 7b . . . 7x) that deliver individual components of the eluent are controlled accordingly. After reaching the final migration of the eluent front, the delivery of the components is stopped, and then the plate (18) is removed from the chromatographic chamber (3) and dried under the hood. As a result, the developed chromatogram is obtained. (19), and the signals of the eluent front migration distance are registered by the computer (20), and based on this information, the pumps (7a, 7b . . . 7x) that deliver individual components of the eluent are controlled accordingly. After reaching the final migration of the eluent front, the delivery of the components is stopped, and then the plate (18) is removed from the chromatographic chamber (3) and dried under the hood. As a result, the developed chromatogram is obtained. After reaching the final migration of the eluent front, the delivery of the components is stopped, and then the plate (18) is removed from the chromatographic chamber (3) and dried under the hood. As a result, the developed chromatogram is obtained. After reaching the final migration of the eluent front, the delivery of the components is stopped, and then the plate (18) is removed from the chromatographic chamber (3) and dried under the hood. As a result, the developed chromatogram is obtained.

Claims

1. A method for delivering the liquid to the adsorbent layer, in which the liquid stream is directed to the outer surface of the adsorbent layer, characteristic in that the liquid stream moves on the outer surface of the adsorbent layer along the set path.

2. A method according to the claim 1 characterized in that the path is a straight line (50, 68, 77, 81).

3. A method according to claim 1 characterized in that the path has the shape of a broken line (72, 86).

4. The method according to claim 1 characterized in that the path is in the shape of a closed line (64).

5. A method according to claim 1 characterized in that the path consists multiple separate lines (91a, 91b. . . 91x).

6. The method according to claim 1 characterized in that the path is of any shape.

7. The method according to claim 1 characterized in that the liquid is an eluent and/or its constituents.

8. A method according to claim 1 characterized in that the liquid is a test solution or an investigated solution.

9. The method of claim 1 characterized in that the liquid stream moves along a predetermined path, from the first turning point (21, 51) to the second turning point (22, 52) and back.

10. The method according to claim 9 characterized in that the speed of travel from the first turning point (21, 51) to the second return point (22, 52) differs from the speed of travel from the second turning point (22, 52) to the first turning point (21, 51).

11. The method according to claim 9 characterized in that the speed of travel from the first turning point (21) to the second turning point (22) is lower than the speed of travel from the second turning point (21) to the first turning point (22).

12. The method according to claim 9 characterized in that the first turning point (21) and the second turning point (22) lie below the adsorbent layer.

13. The method according to claim 9 characterized in that the first turning point (51) and the second turning point (52) lie outside the outline of the adsorbent layer.

14. The method according to claim 1 characterized in that the liquid stream moves in one direction, at a constant speed.

15. The method according to claim 1 characterized in that the liquid stream is successively moved over the surface of at least two separate adsorbent layers (55a, 55b, 55c, 55d).

16. The method according to claim 7 characterized in that the yield of the eluent and/or its constituents varies over time.

17. The method according to claim 16 characterized in that the liquid efficiency, and in particular the eluent efficiency, is equal to or lower than the rate of absorption of the eluent by the adsorbent layer.

18. The method according to claim 16 characterized in that the eluent yield is greater than the absorption rate of the eluent by the adsorbent layer.

19. The method according to claim 18 characterized in that the excess of the eluent is gravity gathered and collected in the gutter (54), then if need be contaminations are removed and the missing components refilled, and then re-supplied to the adsorbent layer.

20. The method according to claim 7 characterized in that the quantitative and qualitative composition of the eluent changes over time.

21. The method according to claim 20 characterized in that the individual components of the eluent are pumped separately, then they are combined directly before or on the outer surface (28) of the adsorbent layer (24).

22. The method according to claim 21 characterized in that each of the eluent components is pumped through the separate tube (9a, 9b, 9c. . . 9x).

23. A method according to claim 22 characterized in that each component of the eluent is pumped with a separate flexible tube (42a, 42b, 42c) into the collector (38) in which they are joined and the eluent thus obtained is delivered, through the common rigid tube (37) to the outer surface of the adsorbent layer.

24. The method according to claim 1 characterized in that the eluent stream is stimulated to transverse vibrations.

25. The method according to claim 1 characterized in that the axis (33) of the aggregate liquid stream (32) is perpendicular to the outer surface (28) of the adsorbent layer (24).

26. The method according to claim 1 characterized in that the liquid stream axis intersects the outer surface of the adsorbent layer at a sharp angle.

27. The method according to claim 1 characterized in that the liquid stream is below the adsorbent layer.

28. The method according to claim 1 characterized in that the liquid stream is over the adsorbent layer.

29. The method according to claim 7 characterized in that during the delivery of the eluent to the adsorbent layer, the eluent front advancement on the adsorbent layer is observed and the amount of the eluent and/or its composition is adjusted accordingly.

30. The method according to claim 7 characterized in that the components of the eluent are preferably delivered in the form of separate streams which, depending on the needs, are specific solvents, solutions thereof and/or substance solutions in solvents.

31. The method according to claim 1 characterized in that the aggregate stream (32) is formed from several individual streams (26a . . . . 26x).

32. The method according to claim 24 characterized in that the rigid tube (37) has the form of a hole in the collector wall (38).

Description

[0022] The method of liquid delivery to the adsorbent layer is presented in the example implementations on a schematic drawing in which:

[0023] FIG. 1 shows the schematic diagram of the eluent delivery system;

[0024] FIG. 2 shows the enlarged detail A from FIG. 1;

[0025] FIG. 3 shows the view W.sub.1 from the direction indicated in FIG. 2;

[0026] FIG. 4 shows the enlarged detail A from FIG. 1;

[0027] FIG. 5 shows the view W.sub.2 from the direction indicated in FIG. 4;

[0028] FIG. 6 shows the chromatogram image obtained in Example I;

[0029] FIG. 7 is the schematic diagram of the first, alternative system for the eluent delivery;

[0030] FIG. 8 shows the chromatogram image obtained in Example II;

[0031] FIG. 9 shows the schematic diagram of the second, alternative system for the eluent delivery;

[0032] FIG. 10 shows the plan view of the inside of the chamber of the second alternative system from the direction W.sub.3 indicated in FIG. 9;

[0033] FIG. 11 shows the view of the plate with applied internal standard solutions and test solutions in order to conduct the instrumental analysis according to Example III;

[0034] FIG. 12 shows the two stages of the chromatogram development on the plate shown in FIG. 11;

[0035] FIG. 13 shows the view of the plate shown in FIG. 11 after concentration of the spots;

[0036] FIG. 14 shows the view of the plate prepared for the instrumental analysis according to Example IV;

[0037] FIG. 15 shows the view of the plate shown in FIG. 14 after the chromatogram has been developed;

[0038] FIG. 16 shows the view of the plate shown in FIG. 14 after the initial concentration;

[0039] FIG. 17 shows the view of the plate prior to final concentration;

[0040] FIG. 18 shows the view of the plate prepared for the chromatogram development according to Example V;

[0041] FIG. 19 shows the view of the plate with the developed chromatogram.

[0042] FIG. 1 shows the schematic diagram of a basic system for delivering the eluent to the adsorbent layer. The system consists of a hydraulic unit (1), a three-dimensional machine (2), a chromatographic chamber (3) and a control unit (4).

[0043] The hydraulic unit consists of a series of identical supply lines (5a, 5b, 5c. . . 5x). The first supply line (5a) consists of the first reservoir (6a) connected to the first pump (7a), which has the outlet to which the first flexible tube (8a) is connected and then terminated with the first rigid tube (9a). All the flexible tubes (8a, 8b, 8c . . . 8x) along with the rigid tubes (9a, 9b, 9c. . . 9x) are connected into a bundle (10) at a certain part of the length. The tip (11) of the bundle (10) is attached to the support (12) of the three-dimensional machine (2). The reservoirs (6a, 6b, 6c . . . 6x) are intended for the eluent or its separate components, which, depending on the needs, are specific solvents, their solutions and/or solutions of substances in the solvents. The tip (11) adheres to the working segment of the vibrator (13), which, if necessary, stimulates it to vibrate for better mixing of solutions pumped through rigid tubes (9a, 9b, 9c. . . 9x), while the vibration amplitude does not exceed several internal diameters of the rigid tube (9a).

[0044] The three-dimensional machine (2) consists of a base (14) to which the first lead screw (15) is mounted together with the support (12) with a transverse carriage (16) driven by the second lead screw (17). The first lead screw (15) is driven by the first electric motor (15a) and the second lead screw (17) is driven by the second electric motor not shown in the drawing. The three-dimensional machine (2) allows the tip (11) of the bundle (10) to travel along the two mutually perpendicular directions, under almost the entire surface of the chromatographic plate (18), hereinafter referred to as the plate (18).

[0045] Inside the chromatographic chamber (3), there is a plate (18), in a horizontal position, directed with the adsorbent layer downwards, while over the plate (18) there is a camera (19) mounted to observe the progress of the eluent front.

[0046] The camera (19) is connected to a computer (20), which simultaneously controls the operation of the pumps (7a, 7b, 7c . . . 7x) and the three-dimensional machine (2), and the position of the tip (11) relative to the entire surface of the plate (18), starting from the first turning point (21) to the second turning point (22) along the path lying in the plane of the drawing.

[0047] The control unit (4) consists of a computer (20) in combination with a camera (19) and electric executive elements, including circuit switchers incorporated in the electric supply circuits of the pumps (7a, 7b, 7c . . . 7x) and electric motors (15a) driving the lead screws (15, 17).

[0048] FIG. 2 shows the enlarged detail A comprising the tip (11) and the plate (18), and FIG. 3 shows the top view of the tip (11) from the side of the plate (18). The tip (11) consists of four rigid tubes adjacent to each other (9a, 9b, 9c. . . 9x) and connected by a band (23). The plate (18) in turn consists of an adsorbent layer (24) adhering to the carrier plate (25) made of a transparent material. From each of the rigid tubes (9a, 9b, 9c. . . 9x) single streams (26a, 26b, 26c . . . 26x) flow out, which combine and thereby mix between the tip (27) of the tip (11) and the outer surface (28) of the adsorbent layer (24) and then also on it.

[0049] FIG. 4 shows the enlarged detail A showing how the tip (11) could be built. The tip (11) is equipped with a nozzle (30) inside which the single streams (26a, 26b, 26c . . . 26x) join and the combined stream (32) flows out through the exit hole (31), the axis (33) of which is perpendicular to the outer surface (28) of the adsorbent layer (24).

[0050] FIG. 5 shows the nozzle (30) from a top view. The nozzle (30) is in the form of a rotatable solid, and its axis (33) has the exit hole (31).

EXAMPLE I

[0051] The arrangement shown in FIGS. 1, 3 and 4 was used to supply the eluent according to the method of the invention in order to separate the mixture by gradient elution, using only the first two supply lines (5a, 5b). The first supply line (5a) delivers the first solution, which is a solution of 100 mM trifluoroacetic acid in methanol. The second supply line (5b) provides the second solution, which is a solution of 100 mM trifluoroacetic acid in water. As a plate (18), a 1020 cm HPTLC RP-18W chromatographic plate from Merck was used, on which 2 L volume portions of test dye mixture were applied in eighteen places to the start line, parallel to the long edge of the plate (18). The portions of the test mixture were applied using the Camag's Linomat V semi-automatic sample applicator. The space between the cylinder and the piston of the 20 mL syringe was used as the reservoir, and the syringe pump was used as a pump. As a three-dimensional machine (2), the drive mechanism of a three-dimensional printer was used. Flexible tubes (8a, 8b, 8c . . . 8x) were made of Teflon with internal diameter of 0.2 mm and external diameter of 1.6 mm, while rigid tubes (9a, 9b, 9c. . . 9x) were made of stainless steel tubes with an internal diameter 0.2 mm and external 0.8 mm. The distance of the nozzle (30) from the surface of the adsorbent layer was set to 0.1 mm, with the exit hole diameter being 0.5 mm, and the movement speed from the first turning point (21) to the second turning point (22) was 30 mm/s and the return speed was 100 mm/s.

[0052] In order to develop the chromatogram, the previously prepared plate (18) is placed in the chromatographic chamber (3), to which the tip (11) enters from below. The first solution is then pumped until the first flexible tube (8a) and the rigid tube (9a) are filled and the second solution is pumped until the second flexible tube (8b) and the second rigid tube (9b) are filled. The total pumping yield of both solutions was set before the experiment and was between 2 and 5 mL/h, that is below the absorption rate of the eluent by the adsorbent, wherein with the first pump (7a) delivers the first solution with a yield of 1.6 to 3.0 mL/h and the second pump (7b) pumps the second solution in a flow rate of 0.2 to 3.0 mL/h.

[0053] The tip (11) terminated with the nozzle (30) is then set at the first turning point (21), and then by means of the three-dimensional machine (2) it is moved to the second turning point (22) and back, while simultaneously both solutions are pumped with variable efficiency controlled by computer (20). The pumping efficiency of both solutions was programmed to obtain the following percentage concentrations of both solutions depending on the distance traveled by the eluent front:

[0054] 1) 40% of the first solution plus the second solution of ad 100, the distance traveled by the front of the eluent from 0 (starting line) to 10 mm, the efficiency of the eluent delivery 5 mL/h,

[0055] 2) 60% of the first solution plus the second solution of ad 100, the distance traveled by the front of the eluent from 10 mm to 20 mm, the efficiency of the eluent delivery 5 mL/h,

[0056] 3) 70% of the first solution plus the second solution of ad 100, the distance traveled by the front of the eluent from 20 mm to 40 mm, the efficiency of the eluent delivery 3 mL/h,

[0057] 4) 80% of the first solution plus the second solution of ad 100, the distance traveled by the front of the eluent from 40 mm to 70 mm, the efficiency of the eluent delivery 2 mL/h,

[0058] 5) 90% of the first solution plus the second solution of ad 100, the distance traveled by the front of the eluent from 70 mm to 80 mm, the efficiency of the eluent delivery 2 mL/h.

[0059] Both solutions are premixed in the nozzle (30) and further on the outer surface (28) of the adsorbent layer (24). This is when the adsorbent layer (24) is wetted with the eluent solution, which leads to the development of the chromatogram. At the same time, the digital camera (19) registers the position of the moving eluent front visible through the carrier plate (25) and the signals on the migration distance of the eluent front are collected via the computer (20) and the pumps (7a) and (7b) respectively are controlled based on this information that deliver the eluent components, with a programmed ratio, to the adsorbent layer.

[0060] After reaching the fmal migration distance of the eluent front 8 cm from the place where the samples were applied to the plate (18), the supply of the eluent components is stopped, then the plate (18) is removed from the chromatographic chamber (3) and dried under the hood. As a result, the chromatogram depicted in FIG. 6 was obtained.

[0061] FIG. 7 shows a schematic diagram of the first alternative system for delivering the eluent. This arrangement is presented with omission of the control unit, which is as shown in FIG. 1. Inside the chromatographic chamber (35), there is a plate (36) in a horizontal position directed with the adsorbent layer upwards. Above it there is a rigid tube (37) connected to the collector (38), with three identical supply lines connected to the collector (38) (39a, 39b, 39c). The first supply line (39a) consists of the first reservoir (40a) connected to the first pump (41a), to the outlet of which the first end of the flexible tube (42a) is connected, which in turn the second end is connected to the collector (38). The collector (38) is attached to the three-dimensional machine (43).

[0062] The three-dimensional machine (43) contains a body (44) to which the first lead screw (45) is mounted together with the support (46) on it and with transversely located carriage (47) driven by the second lead screw (48). The first lead screw (45) is driven by the first electric motor (49), and the second lead screw (48) is driven by the second electric motor not shown in the drawing.

[0063] The three-dimensional machine (43) enables the movement of the collector (38) with the rigid tube (37) along the path of a straight line (50) lying in the plane of the drawing from the first turning point (51) to the second turning point (52) and along the paths of any shapes over the plate (36), in a rectangular coordinate system.

EXAMPLE II

[0064] The method according to the invention has been used to develop the isocratic chromatogram according to the arrangement shown in FIG. 7. A HPTLC plate (36) from Merck with dimensions of 510 cm has an adsorbent in the form of silica gel. Flexible tubes (42a, 42b, 42c) of 1.6 mm external diameter and 0.2 mm internal diameter are made of Teflon, whose end parts are connected to a collector (38) of negligible capacity. The rigid tube (37) is made of a 50 mm long stainless steel tube of 1.6 mm outer diameter and 0.2 mm internal diameter. The outlet of the rigid tube (37) moves over the adsorbent layer of the plate (36). A specific composition of the solution supplied to the adsorbent layer is obtained through the appropriate speed of delivery of the individual eluent components from the supply lines (39a, 39b, 39c), toluene, ethyl acetate and methanol, respectively. In a particular case, the function of the rigid tube (37) may be filled by the outlet hole in the collector wall (38).

[0065] On the start line, 1 cm from the edge of the plate (36) and parallel to it, the solutions in the count of 9 were applied, mixtures of three dyes (3 places of application on the starting line) and solutions of individual dyes (6 places-2 places for each dye: orange, yellow and blue) using the Linomat 5 aerosol applicator from Camag. Next, an eluent was supplied to the adsorbent layer, which was pure toluene from the first supply line (39a). The distance of the end of the rigid tube (37) from the adsorbent layer was 0.2 mm and the length of the moving path was greater than the width of the plate (36) and was between the first turning point (51) and the second turning point (52). This line ran between the starting line and the closer to it parallel edge of the plate (36). The travel speed of the tip of the rigid tube (37) above the plate (36) was constant in both directions and was 30 mm/s, the speed of toluene delivery to the adsorbent layer during the chromatogram development process was also constant and was 5 mL/h. Through the other two supply lines (39b, 39c), in this experiment, the pumps did not pump solvents. Once the eluent front has traveled the distance of 4.0 cm from the starting line the solvent supply was stopped. The duration of this process was 10 minutes. The chromatographic plate was then dried and photographed. The image of the chromatogram obtained is shown in FIG. 8.

[0066] FIG. 9 is a schematic diagram of the second alternative system for delivering the eluent. In the chamber (53) there is a gutter (54) above which the plates (55a, 55b) are placed at an angle a relative to the level and directed with the adsorbent layer upwards, with the first plate (55a) being above the first side (54a) of the gutter (54), and the second plate (55b) being above the other side (54b). However, over the second plate (55b) there is a rigid tube (56) connected via a flexible tube (57) and a pump (58) to the reservoir (59). The rigid tube (56) can also move over the first plate (55a) thanks to the three-dimensional machine, not shown in the drawing, to which it is attached, constructed like the three-dimensional machine (43) shown in FIG. 7. The stream axis flowing out of the rigid tube (59) intersects the second plate (55b) at a sharp angle . The reservoir (59), on the other hand, is connected to the gutter (54) via the drain line (60) on which the filter (61) is mounted. Two dispensers (62, 63) are also connected to the reservoir (59).

[0067] In order to supply the eluent to the adsorbent layer, the eluent is pumped through the pump (58) to the rigid tube (56) in the amount exceeding its absorption capability by the adsorbent layer, and the excess flows by gravity into the gutter (54), and then further through the filter (61) to the reservoir (59), where from the dispensers (62, 63) the quantity and composition of the eluent is replenished to the initial parameters, and then the regained eluent is further supplied to the adsorbent layer.

[0068] FIG. 10 shows the top view of the interior of the chamber of the second, alternative arrangement from the direction W3 indicated in FIG. 9. Plates are arranged along the gutter (54). The first series of plates (55a, 55c) is arranged above the first side (54a), and the second series of plates (55b, 55d) is arranged above the second side (54b). Over the second plate there is a rigid tube (56) which, by the not shown three-dimensional machine, is moved over both rows of plates, along the path in the shape of a closed line (64) at a speed of 200 mm/s.

EXAMPLE III

[0069] The method of the invention has been used to prepare samples for instrumental analysis. In the first stage, nine standard solutions of paracetamol and acetanilide with the volume of 20 L are applied with a microsyringe onto a chromatographic plate (65), 1020 cm HPTLC from Merck with a layer of silica gel that is directed upwards along the starting line (66), spaced 1 cm from the long edge (67) of the plate (65). The concentration of acetanilide in these solutions was constant, whereas the concentration of paracetamol was varying. In addition, 20 L of the test solution containing an unknown amount of paracetamol and the known acetanilide is applied in each of the further three locations on the start line. FIG. 11 shows the plate (65) with the nine standard solutions and the three test samples applied this way, which were marked 1-9 and X1-X3, respectively.

[0070] FIG. 12 shows the next two stages of the chromatogram development. Once the spots containing solutions of the substances applied to the start line (66) have dried, an isocratic chromatogram will be developed utilizing the apparatus shown in FIG. 7 with the use of the third supply line (39c) filled with methanol. In the first stage, methanol is supplied to the adsorbent layer with a capacity of 5 mL/h, at a moving speed of the rigid tube (37) equal to 50 mm/s at a distance of 0.1 mm above the adsorbent layer between the starting line (66) and the closer to its longer edge (67) of the plate (65) over the distance of 196 mm. This movement is repeatedly carried over along the straight line path (68) from the first turning point (69) to the second turning point (70) and back. Methanol is delivered until the eluent front reaches a distance of 30 mm from the starting line (66), after which the plate (65) is dried. During the delivery of the eluent, the target substance (paracetamol) and the internal standard (acetanilide) migrated practically with its front in the form of spots (71a).

[0071] In the second step, the plate (65) is again subjected to methanol delivery to the adsorbent layer to obtain concentrated and narrowed substance zones (paracetamol and acetanilide). The methanol is supplied along a broken line path (72), from the first turning point (73) to the second turning point (74) and surrounding each of the spots (71a) on three sides. The broken line (72) consists of many straight sections and arcs. The methanol is supplied to the adsorbent layer with a efficiency of 2.5 mL/h at a rate of moving of the rigid tube (37) equal to 20 mm/s. Periodic movement of the rigid tube (37) over the adsorbent layer is interrupted when the adsorbent layer is completely wetted in the area of this road. FIG. 13 shows the concentration effect. The spots (71a) were significantly reduced and concentrated to the points (71b).

[0072] After evaporation of the solvent (methanol), the adsorbent layer at the location of the respective paracetamol and acetanilide zones is scraped and transferred to separate vessels to which known amounts of methanol are added. The obtained suspensions are filtered, and the obtained solutions are subjected to the determination of paracetamol by the well-known method of the internal standard, using a high performance liquid chromatograph with a UV detector.

EXAMPLE IV

[0073] The preparation of a sample for instrumental analysis is shown in the steps in FIGS. 14-17. In a preliminary step, nine standard solutions containing known concentrations of three substances (acetylsalicylic acid, caffeine and paracetamol) of 20 L are applied with a microsyringe onto a 1020 cm HPTLC RP-18W plate from Merck with a silanized silica gel layer that is along the start line (75), spaced 10 mm from the long edge (76) of the plate (74). The concentration of caffeine in these solutions was constant, while the concentration of acetylsalicylic acid and paracetamol had different values. Then, in three places on the start line (75), 20 L of the test serum solution containing an unknown amount of acetylsalicylic acid and paracetamol and a known amount of caffeine are applied. FIG. 14 shows the application sites of the nine standard solutions and the three solutions of tested serum, which were marked 10-18 and X4-X6, respectively. The prepared plate (74) is dried.

[0074] Simultaneously, the arrangement shown in FIG. 7 is prepared for developing the isocratic chromatogram, in which the first line (39a) is filled with acetonitrile, the second line is filled with a buffer containing: a solution of 0.2 M sodium monophosphate(V) and 0.1 M solution of citric acid, pH 3.2, and the third line (39c) is filled with methanol. The plate (74) is placed in the chamber (35).

[0075] Then, in the second step, from the first line (39a) and the second line (39b), the eluent components are delivered to the adsorbent layer. Both lines (39a, 39b) supply solutions with different yields so that the eluent has a composition of 25% acetonitrile and 75% buffer. The total efficiency of the mobile phase delivery to the adsorbent layer was 5 mL/h. The third line (39c) was not used at this stage of the experiment.

[0076] FIG. 15 shows the first and the second stage of chromatogram development. The end of the rigid tube (37) moves repeatedly over the adsorbent layer between the starting line (75) and the longer edge (76) along the first path (77) in a straight line from the first turning point (78) to the second turning point (79) and back again. The migration speed of the rigid tube (37) was 20 mm/s, and the distance of its tip from the outer surface of the adsorbent was 0.1 mm.

[0077] The development of the chromatogram was stopped when the eluent front reached the distance of 60 mm from the starting line (75). Under these conditions, the substances of interest: salicylic acid and paracetamol, and the internal standard: caffeine, showed values of the retardation coefficient, R.sub.F, 0.35, 0.48, 0.30, respectively. In this state, the plate (74) is dried, and then the second step is administered.

[0078] The first line (39a) and the second line (39b) are turned off, while from the third line (39c) methanol is delivered into the adsorbent layer with the efficiency of 5 mL/h and the travel speed of the tip of the rigid tube (37) equal to 20mm/s at a distance of 0, 1 mm from the adsorbent layer along the second path (81) in a straight line from the first turning point (82) to the second turning point (83) and back. The second path (81) is 20 mm away from the long edge (76). After reaching a 25 mm front migration distance (84) of methanol, measured from the second path (81), the methanol supply is stopped and the plate (74) is dried. FIG. 16 shows the effect of the second stage of the chromatogram development.

[0079] In the third step, shown in FIG. 7, a rigid tube (37) is led along the third path in the shape of a broken line (86) from the first turning point (87) to the second turning point (88) via intermediate points (89a, 89b, 89c, 89d . . . 89x) and back to the first turning point (87) skipping the intermediate points (89a, 89b, 89c, 89d . . . 89x). The third path (86) surrounds the subsequent spots interchangeably from three sides (90a, 90b . . . 90x). Methanol, on the other hand, only runs on the vertical sections (91a, 91b . . . ) of the third path (86), breaking its pumping during the passage of the rigid tube (37) over the horizontal sections (92a, 92b . . . ) parallel to the long edge (76) and in time of return. The methanol supply is stopped when the adsorbent layer between the vertical sections (91a, 91b, . . . ) is completely wetted.

[0080] The third step can also be carried out according to a variant in which methanol is delivered along the vertical segment (91a) back and forth until the solvent front reaches the center of the spot (90a), and then the rigid tube (37) moves to the second vertical section (91b) and methanol is delivered until the first emerging front reaches the center of the first spot (90a) and the second front reaches the center of the second spot (90b) and so on until the adsorbent is wetted between the vertical sections (91a, 91b, . . . ) of all spots (90a, 90b . . . 90x).

[0081] As a result of the implementation of the third stage the substance zones (acetylsalicylic acid, caffeine and paracetamol) were significantly reduced and concentrated.

[0082] The substances found in the concentrated zones were extracted with methanol in the usual manner using the Camag's TLC-MS Interface device connected to a liquid chromatography pump. This resulted in 12 solutions, corresponding to nine standard solutions and three tested, which were previously applied to the start line. The obtained solutions were subjected to the determination of acetylsalicylic acid and paracetamol by a known method in which caffeine was an internal standard, using a high performance liquid chromatograph with a UV detector and mass spectrometer.

EXAMPLE V

[0083] The method of the invention has also been used for preparative separation of substances mixture with the use of the system shown in FIG. 7. For this purpose, the first supply line (39a) is filled with a toluene solution of three dyes: 1-aminoanthraquinone, 2-nitroaniline and the fat green. The second supply line (39b) is filled with toluene, which acts as the eluent here, and the third supply line (39c) is not used. Then a plate (94) with dimensions of 200200 mm with a layer of 0.5 mm thick silica gel is placed in the chromatographic chamber. Further, from the first supply line (39a), a dye solution is pumped along the start line (95) constituting the plate axis (94), until a band (96) of dyes to be separated with a width of 10 mm is obtained. At this point, the supply of the dye solution is stopped and the delivery of the eluent is started via the second supply line (39b) along the path that coincides with the starting line (95). This condition is shown in FIG. 18.

[0084] During this process, the eluent wetted the adsorbent layer simultaneously in two opposite directionsfrom the start line (95) to the opposite edges of the plate (94). When the eluent front reached both opposite edges of the chromatographic plate, the toluene supply was stopped, and the adsorbent layer was dried from the solvent. FIG. 19 shows the preparative chromatogram obtained in this example with bands of separated dyes. Next, the zones of the adsorbent layer in which the bands of separated substances were located were mechanically transferred to appropriate filters placed in three glass funnels and extracted with methanol. The extracts were collected in separate three vessels. In this way, separate methanol solutions of each dye were obtained. The evaporation of methanol yielded pure dyes.