Apparatus For Simultaneous Application Of Samples To Thin Layer Chromatography Plates

Abstract

A thin layer chromatography apparatus with universal V-groove seats to support syringes and a movable arm with a resilient pad lowered and locked against the top of the syringes. An adjustable needle positioning means operates to align the tips of all the needles, and then is rotated to press down on the needles to selectively lower the tips relative to the plate. A variable drive member reciprocates a pusher member for the syringes, said drive member traveling along a rotatable screw which is reversible following contact of limit switches during travel of the drive member. A controlled heating element and air jets may be used to hasten rate of solvent evaporation during application of liquid samples to thereby assist reproductibility of sample application.

Description

This invention relates to an apparatus for delivering small volumes from one or more syringes onto thin layer chromatography (TLC) plates at slow delivery rates so that large volumes or samples can be deposited in small spots.

Both paper chromatography and TLC techniques are characterized by deposit of a sample onto a surface and then identifying the compound or compounds in the spotted sample by its pattern of migration on the surface of a chromatographic development. There is a recognized relationship between physical and chemical properties and rate of migration. Both procedures often use a plurality of syringes to deposit a number of adjoining samples onto the surface. This increases the efficiency in that a greater number of analyses may be conducted and compared on one paper strip or TLC plate. The art has come to recognize that one important problem is the spreading and overlapping of adjoining spots on the surface. This understandably interferes or nullifies the results.

The desired goal is to deposit as large a sample as possible on as small a spot as possible. In this way, a large amount of compound or solute will be deposited on a very small area. The paper chromatography art has developed the approach of depositing the sample in very small volumes and at a very slow rate so that the volatile solvent carrier evaporates as the drop is formed so that more solute and less solvent is deposited as the spot on the surface. Micropipettes have been used to serve this purpose as well as microsyringes in which the plunger is slowly actuated manually at a slow rate.

It is one important object of the present invention to provide a TLC apparatus in which a plurality of syringes are disposed for depositing minute volumes of sample onto TLC plates in an improved manner.

Another important object of the present invention is to provide a TLC apparatus of an improved design in which a gang of syringes are immobilized in a means which can accommodate a variety of syringe barrel diameters without requiring special fittings, adjustments, or the like.

Still another important object of the present invention is to provide a TLC apparatus of improved design wherein aligned needles in a gang of syringes are adjustably repositioned relative to a TLC plate by means which are quickly and reliably actuated to move the gang of needles to any one of a number of positions which may be selected.

Still yet another important object of the present invention is to provide a TLC apparatus of improved design which allows quick and reliable infinite adjustment of a gang of syringe needles so that the tips of all the needles are identically repositioned relative to a TLC plate.

Yet another important object of the present invention is to provide a TLC apparatus of improved design in which a pusher member for a gang of syringes executes forward and reverse travel under control of a drive member which reciprocates along a driving means with control limits to stop and reverse the travel therealong.

Still yet another important object is an improved TLC apparatus having controlled heating means for inducing rapid solvent evaporation while applying the sample, as well as optionally operated air jet means useful for hastening solvent evaporation in the presence of heat labile compounds .

Such objects are now attained, together with still other objects which will become evident from time to time by considering the invention in the following disclosure, which includes drawings wherein:

FIG. 1 is a top plan view of the improved apparatus of the invention;

FIG. 2 is a side elevational view of the apparatus of FIG. 1;

FIG. 3 is a sectional view along line 3--3 of FIG. 1;

FIG. 4 is a side sectional view on an enlarged scale, of the apparatus, with portions removed;

FIG. 5 is a portional section view along line 5--5 of FIG. 4;

FIG. 6 is a portional section view along line 6--6 of FIG. 4;

FIG. 7 is a portional side view partly in section, showing the needle adjustment means in needle positioning attitude; and

FIG. 8 is a portional top plan view, partly in section, and on the same scale as FIGS. 5-7, showing manual means for infinitely adjusting the needle repositioner.

The use of the same numerals in the various views of the drawings will indicate a reference to like parts, structures or elements, as the case may be.

Referring now to the drawings, the apparatus illustrated includes a generally box-like housing 10 having opposed sidewalls 12, opposed end walls 14, a top wall 16, and a bottom wall or floor 17. On the top wall of the housing is positioned a TLC glass plate 18 which inner edge is correctly positioned by a transverse stop element 19. One side of the plate is contacted by a spring urged ram 20 of a pusher member 21 mounted to top wall 16, the spring mechanism not being shown. A pair of opposite position pins 22 fix the position of the plate against the pusher 21. An electrical heater element 23 is shown under the glass so that it is located below the sample spotting site. The heating element spans the spotting sites, and its temperature is adjusted by means such as variable resistance to hasten evaporation of solvent in the sample.

The TLC glass plate is conventionally prepared, and mono-dimensional high voltage thin-layer electrophoresis, that is, for TLC procedures. After the TLC plate is spotted according to the teaching of the present invention, it is conventionally processed to quantify the deposited spots for identifying the compounds deposited at such spots.

A syringe grouping or gang shown generally as 24 extends transversely along the top of the housing. Each syringe is identified by the usual syringe barrel 25, syringe plunger 26 with head 27, and needle 28.

A pusher element or bar 39 also extends transversely along the top of the housing for contacting heads 27 of the syringes.

A hold down means shown generally as 34 also extends transversely along the top of the housing. The hold down means includes a spanning arm 35 which is joined by a pivot 36 to pivot plate 37 which is opposed by locking plate 38. The opposite end of the pivotable spanning arm 35 has an interlock assembly, shown with a translatable pin 39 in an oversized locking aperture 40. A detent 41 has a tapered opening 42 engageable by tapered face 43 of pin 39. The detent is urged outwardly into locking engagement with catch 44 fixed to locking plate 38. Pin 39 may be pressed downwardly to move detent 41 out of locking engagement, said pin 39 thereby being translatable in oversized aperture 40 towards pivot plate 37.

Bottom three point supports for the syringe are positioned on the top wall 16 of the housing. The supports are shown as three transverse walls, lower syringe support 45, upper syringe support 46, and intermediate syringe support 47. The top edge of each support wall is provided with a plurality of universal syringe V-seats 48, the three walls providing three aligned V-seats for each syringe. Such V-seats allow syringe barrels of varying diameters to be seated therein, as will be readily understood.

The hold down means for the syringes is also shown as including an elongated resilient pad 54 mounted to the arm 35. It will be seen that when the pivotable arm is fully lowered so that the interlock assembly is actuated, the resilient pad and arm will accommodate themselves to the particular syringe barrel diameter seated in aligned V-seats in the transverse wall supports. This will assure the immobility of the gang of syringes during operation of the apparatus.

The selective adjustment or needle positioning means, includes an elongated bar 62 with opposite end right angle walls 63. Such bar therefore assumes the profile of an angle element. The end walls 63 are pivoted to opposite upright walls 37, 38 at pivots 64. The bar or element 62 has a flat surface to position the tips of the needles in alignment. An air tube 65 extends to the opposite end walls 63, and such tube is connected to a source of compressed air (not shown) through line 66. The end walls 63 have journal openings for the air tube so that selective positioning means may be rotated around the tube. A plurality of air jets 67 are on the underside of the tube, aligned along the length of the tube and generally coincidental with the ends of the needles. Controls, not shown, actuate passage of air through the tube and out the openings as pressurized jets to hasten evaporation of solvent when the compounds are heat labile.

The opposite end wall 63 is shown pivoted to an infinite adjustment means, shown generally as 68. Such means include a flanged head pin 69 which has a knurled stub 70 which is non-rotatably fitted in wall bore 71. The shank 72 of the pin is rotatable within bearing 73. The infinite adjustment means is actuated by manually rotating knob 74. Such knob has an upper enlarged recess 75 which communicates with narrow passage 76. A pair of opposed belleville springs collectively shown as 77 are disposed within the upper large recess 75. Such springs are fixed to shank 72 of the pin so that the combination of the belleville springs urges one spring against the upright wall and the outer spring against the bottom of upper recess 75. A reduced diameter portion 78 is provided in the shank of the pin, and said portion is aligned with threaded set screw passageway 79 in the knob. A set screw 80 fixes the pin 69 upon moving into a part of narrow passage 76 provided by reduced diameter portion 78.

The elongated angle is rotated substantially 180.degree. from the position generally shown in FIG. 4 to the position generally shown in FIG. 7. This rotation is effected by manually rotating knob 74 which can be stopped at any one of an infinite number of positions in theory. The opposed belleville springs provide sufficient frictional contact between the knob and the housing part to stop the element in any rotated position. In this way, an edge of the elongated element as shown in FIG. 7, contacts the top of the needles and moves them downward until the tip of the needles are selectively positioned relative to the TLC plate 18.

The apparatus is provided with a control board 84 provided with an on-off master switch S, and a test start switch T to start the motor. An adjustable heat control H has graduations to control the temperature of element 23, such temperature being read on pyrometer P. A calibrated control C adjusts the rotational speed of screw 89 through fixed gradations of from 1 to 10. Such conventional controls are used to operate electric motor 85 which is joined to a gear train box 86 having a desired gear reduction to rotate stub shaft shown threadably engaged in threaded bore 88 of transmission coupling 87. An end of a rotatable screw shaft 89 is also shown threadably engaged in the bore of the coupling transmission.

A drive means shown generally as 90 is reciprocally driven along the rotatable screw shaft 89 which is turned at desired rotational speeds. The drive means includes a body member 91 having a cutout 92 which opens at the back wall 93 and the top wall 94 of the body member. A driving arm 95 is pivoted within the cutout at 95a, and such arm extends out of track or groove 96 in the top wall 16 of the housing. A belleville type spring 97 normally urges the driving arm 95 into normal relationship with the plane of the top wall 16. Spring 98 within the cutout 92 also urges the driving arm into normal relationship with the plane of the top wall 16.

A pin 99 is fixed to a lower part of the driving arm 95, and the spring 98 also urges this pin out of contact with microswitch 100. The end of the pin 99 is shown with a flange 101 to prevent such pin from slipping into cutout 92 under urgings of the spring 98. When the driving arm 95 reaches a limit of travel as defined either by closed end 102 of track slot 96, or the fully inserted positions of the plungers 27 in the syringes, such driving arm will rotate or pivot counterclockwise relative to the view of FIG. 4. Such pivotable movement will urge pin 99 out of the body member 91, and into contact with microswitch 100. This microswitch will then reverse the rotation of screw 89 and thereby reverse the travel of the drive means along said screw towards the back of the housing. Travel of the drive means along the screw towards the rear of the housing will be stopped when back wall 93 of the body member engages contact 106 of a microswitch mounted to backwall 14 of the housing. The actuated microswitch will turn off motor 85, and terminate rotation of screw 89. It will be evident that driving arm 95 may be also manually pivoted to reverse the path of travel of the drive means, thereby affording the user of the apparatus added versatility in the operation thereof.

The bottom wall 108 of the drive member 91 has a threaded semicircular groove 109 which is engaged by the threads of screw 89. The body member is held to the screw by U-shaped clip 110 which is fixed to the opposite sidewalls 111 of the drive member by fasteners 112. The clip has fore and aft bearing pads 114 which slidingly engage the bottom of the screw 89. The clip allows the half nut groove 109 to retain effective engagement with the screw 89 during reciprocal travel of the drive member and during pivotable movement of the driving arm 95.

The claims of the invention are now presented.

Claims

We claim:

1. An apparatus for delivering small volumes from a syringe onto a thin layer chromatography plate, including

a housing,

a thin layer chromatography plate on said housing,

a syringe support on said housing,

means to immovably hold said syringe on said support,

a pusher element translatable along said housing to push a plunger of said syringe,

means in said housing to move said pusher element at selected velocities, and

adjustable means to releasably engage the top of said needle and urge same downwardly so that the needle tip is desirably repositioned relative to said thin layer chromatography plate, said needle returning to its original position upon disengagement of said adjustable means.

2. An apparatus which includes the features of claim 1 above, wherein said adjustable means further includes a needle positioning means to intercept the tip of said needle to desirably position the end of said needle along the length of said thin layer chromtography plate.

3. An apparatus which includes the features of claim 2 above, wherein said adjustable means is an elongated, rotatable element which spans the housing and is pivoted at its opposite ends to housing parts, and wherein an edge of said elongated element contacts the top of the needle when said element is rotated about 180.degree., continued rotation urging said needle downwardly to selectively position the needle tip relative to the thin layer chromatography plate.

4. An apparatus which includes the features of claim 3 above, which further includes manually rotatable means connected to said elongated element, and resilient means intermediate said knob and elongated element which hold said rotatable element to the position to which it is rotated by said manual means.

5. An apparatus which includes the features of claim 4 above, wherein said resilient means are oppositely urged against said manual means and against a housing part, and wherein said oppositely urged resilient means allow infinite adjustment in rotating said elongated element.

6. An apparatus which includes the features of claim 5 above, wherein a group of syringes are aligned on said syringe support, and wherein said holding means span said housing and simultaneously hold all of said aligned syringes on said support.

7. An apparatus which includes the features of claim 6 above, wherein said elongated element has a flat surface element which intercepts the needles of all the syringes to align same along the length of the thin layer chromatography plate, and wherein an edge of said flat surface element engages the tops of the aligned needles upon rotation.

8. An apparatus which includes the features of claim 1 above, wherein said syringe support extends transversely on said housing, said support including a plurality of substantially parallel walls, and aligned V-groove seats at the top edges of each wall to accommodate a syring barrel of varying diameter, and wherein the means to immovably hold the syringe includes an elongated hold down member movable to engage a plurality of syringe barrels, each of which is seated in said aligned V-grooved seats, and means to interlock said elongated member in lowered position against such syringe barrels.

9. An apparatus which includes the features of claim 8 above, wherein said hold down member is pivoted at one of its ends to a housing part, the opposite end having means to form an interlock with another housing part when said hold down member is lowered to engaging position, and an elongated resilient element mounted on said hold down member for contacting the syringe barrels.

10. An apparatus which includes the features of claim 1 above, wherein said pusher element moves along a track extending along the top of the housing, and wherein said pusher element is connected to a drive member within the housing, said drive member adapted to be driven along a rotatable screw, and said screw being rotated by electric motor means joined to control means which may be operated to attain desired rotational speeds for advancing said drive member at desired velocities.

11. An apparatus which includes the features of claim 10 above wherein said drive member carries a pivotable drive arm, one end whereof extends out of said track against said pusher element, said drive arm being pivoted upon encountering predetermined resistance of the pusher element which occurs upon discharge of said syringes, and said pivoted arm actuating reversing means for said screw to induce travel of the drive means in a direction away from the syringes.

12. An apparatus which includes the features of claim 11 above, which further includes an opposed stop means to intercept said drive member in its rearward travel along said rotatable screw to stop the rotation of the screw and the rearward direction of said drive means.

13. An apparatus which includes the features of claim 11 above, wherein said reversing and stop means are microswitches, the reversing microswitch being carried by said drive means, and the stop microswitch being mounted on a rear wall of the housing in the path of travel of said drive means.

14. An apparatus which includes the features of claim 1 above, wherein said pusher element extends transversely along said housing, a plurality of syringes ganged together in aligned position so that each of the plunger heads contact said pusher element in fully closed position, said needle positioning means having a transverse element with a flat surface, and the needles of said ganged syringes aligned in abutting relationship with said transverse element.

15. An apparatus which includes the features of claim 14 above, wherein a track extends along the top of said housing, and a drive arm contacts said pusher element, said drive arm being pivotally linked to a drive member within said housing which is reciprocally driven along a rotatable screw at selected speeds, said drive member carrying reversing means actuated by said drive arm when pivoted by resistance from said pusher member.

16. An apparatus which includes the features of claim 5 above, wherein said syringe support includes parallel walls extending transversely along said housing, the top edges of each of said walls having aligned V-groove seats to accommodate syringe barrels of varying diameters, and wherein said hold down member has a pivotally movable arm having an elongated, resilient pad mounted to the underside, said pad contacting the top of the syringe barrels when lowered, and the non-pivoted end of said arm having means to form an interlock with the housing part when fully lowered to immobilize said ganged syringes.

17. An apparatus which includes the features of claim 16 above, wherein the transverse element of the needle positioning means releasably engages the top of said needles, said transverse element being manually rotatable about 180.degree. to engage the top of said needles, and said transverse element being locked in a selected position following engagement with the top of said needles to desirably lower the tips of the needles relative to said thin layer chromatography plate.

18. An apparatus which includes the features of claim 14 above, which further includes a transverse heating element extending below the aligned tips of said needles to hasten solvent evaporation.

19. An apparatus which includes the features of claim 14 above, which further includes a transverse air tube carried by said transverse element, a plurality of air jets in said tube for directing air jets into the deposited samples to hasten solvent evaporation.