US3401564A

US3401564A - Apparatus for transferring measured samples

Info

Publication number: US3401564A
Application number: US550828A
Authority: US
Inventors: Hrdina Jiri
Original assignee: Czech Academy of Sciences CAS
Current assignee: Czech Academy of Sciences CAS
Priority date: 1965-05-19
Filing date: 1966-05-17
Publication date: 1968-09-17
Anticipated expiration: 1985-09-17
Also published as: GB1119198A; DE1598267A1; DE1598267B2; SE316635B; AT286684B; DE1598267C3; CH459608A; BE681196A

Description

J. HRDINA 3,401,564

APPARATUS FOR TRANSFERRING MEASURED SAMPLES Sept. 17, 1968 3 SheetsSheet 1 Filed May 17, 1966 I NVE NTOR.

J I RI H RDINA Attorney J. HRDINA 3,401,564

APPARATUS FOR TRANSFERRING MEASURED SAMPLES Sept. 17, 1968 5 Sheets-Sheet 2 Filed May 17, 1966 INVENTOR.

J 1R1 E'P )IWA Sept. 17, 1968 3,401,564

APPARATUS FOR TRANSFERRING MEASURED SAMPLES Filed May 1966 s Sheets-Sheet 5 h YDAPA (ll/CAL CHANGE -0VE/? U COLUMN INVENTOR. mif H NA Attorn United States Patent 0 APPARATUS FOR TRANSFERRING MEASURED SAMPLES Jii'i Hrdina, Prague, Czechoslovakia, assignor to Ceskoslovenska akademie ved, Prague, Czechoslovakia Filed May 17, 1966, Ser. No. 550,828 Claims priority, application Czechoslovakia,

May 19, 1965, 3,245/65 6 Claims. (Cl. 73-421) ABSTRACT OF THE DISCLOSURE An arrangement for transferring dosed samples, particularly for automatic analyzers, which includes at least one sample tube; a distributing valve; a discharge tubing; means for connecting one end of said sample tube with said distributing valve while the other end of said sample tube is adapted to be connected with said discharge tubing; means for sealing the connection between said other end of the sample tube and the discharge tubing and means for imparting a relative movement between the second end of the sample tube and the discharge tubing so as to allow alternately free access to this other end of the sample tube, and to accomplish a tight coupling between the sample tube and the discharge tubing.

This invention relates to an arrangement for transferring dosed samples of liquids, especially mixtures of substances designed for analyses in automatic analyzers.

In automatic analyzers, especially for analyses of mixtures of amino acids and similar substances on ion exchanger columns, an important partial unit is a device which will permit dosed samples designed for anaysis to be individually and subsequently at the beginning of every analysis transferred to columns or in general to places of their processing. In highly effective devices, for example for the analysis of mixtures of amino acids, an important requirement is that the samples be transferred automatically to columns with minimum undesirable debasement of the partition which is provided by the column. It is necessary to suppress as much as possible the blurring of zones caused by the decrease of concentration gradients in consequence of mixing with neighboring liquids on storing of samples in recipients and transferring them to the column.

In order that the contribution of the dosing device to this undesirable blurring of zones may be as low as possible, it is necessary that minimum mixing of the sample with the neighboring liquids should occur, both on filling of sample recipients and on storing of samples in these and transferring samples to the column. This requires that the tubing through which the sample is transferred to the column be a capillary one, smooth and as short as possible. From this follows the requirement that the sample recipient can be placed if possible close to the column or to its closure; it further implies the requirement of a permanent and perfect tightness of the sample recipent, especially for operation under considerable pressures which are present in modern analyzers even in values of up to several tenths of atmospheres. At the same time the sample recipient at the time of dosing must be easily disconnectable from the capillary tubing leading to the column in such way that the filling of the samples into the sample recipients may be carried out comfortably, accurately and with minimum danger of a part of 3,401,564 Patented Sept. 17, 1968 the sample adhering to undesirable places from where they would not at the time of beginning of the analysis get to the column.

Devices known at present, especially from the field of gas chromatography, do not comply with the abovegiven requirements, As far as analyses of liquid samples on ion exchangers are concerned, no devices are known whatsoever which would satisfy the requirement of automation of the introduction of a larger number of samples to columns in a simple way. Known is only a device in which the space for the sample is formed by several coils of a flexible capillary which by way of a system of cocks may be manually connected into the pressure branch of the pump forcing the eluent to the column, the hand operating cocks permitting the pressure circuit to be cut off from the above capillary, which can then be filled via some of the changeover cocks.

The arrangement according to the invention fulfills all the above-given conditions together with advantage of comparative simplicity, reability and especially simple operation.

The arrangement according to the invention is essentially formed by at least one sample tube which can be connected tightly into the circuit of the main pump of the analyzer, which tube is 'by one of its en-ds connected to the tubing leading to a hydraulic switch which permits the tube to be connected both to the source securing the inflow of the liquid which causes the dispensing of the sample from the tube to the place of processing and to a suction tubing for sucking on the sample from a sample reservoir, the free end of the sample tubes being preferably adapted to be released and to be inserted into holders in which the inlet and the outlet tubings terminate, which are connected in a through-flow manner with the free end of the tube. One of the ends of the sample tube, preferably the upper one, is purposefully firmly connected to a flexible hose, and the other one, preferable the lower one, is connected to a tubing so that the connection can be disconnected; this tubing may lead to a column via a further distributor valve and tubing.

Further characteristic features of the invention follow from the following description.

Examples of the arrangement according to the invention are schematically represented in the appended drawings. FIG. 1 is a vertical section of one of the sample recipients together with a device securing a releasable sealmg.

FIG. 2 shows in cross section the connection of the flexible hose to a connecting body, FIG. 3 is a side view upon the carrier of a spring, FIG. 4 is a top view upon the lever, on which the sample tube is suspended. FIG. 5 is a cross section of the lower part of the sample tube and of its connection with the discharge tubing. FIG. 6 represents another version with a zig-zag bent sample recipient. FIG. 7 shows an example of a general arrangement with more sample recipients connected into the pressure branch of a pump forcing the eluents to chromatographic columns.

FIGS. 1 to 5 show the sample recipients used in the device in the shape of thick-walled glass capillary tubes 1 which are narrowed at their bottom end 2. The upper end of the tube 1 is connected to a flexible inlet hose 3 which need not be a capillary one. To the upper end of the tube 1 provided with a groove 4 or with a roughened surface is cemented a connecting body 5 for example of stainless steel; the hose 3 is at its lower end 6 flared and sealed by the thrust of a hollow sealing screw 7 which acts via a ring 8 on a sealing ring 9 of silicon rubber. The connecting body is suspended by means of a pivot 10 to a lever 11 swinging round a pivot 12 mounted in a cutout of a plate 13 fastened to the base plate 14. The lever 11 is at its left end provided with a handle 15, at the right end with a cut-out 16 through which passes a screw 17 provided with a nut 18 for limiting the motion of the right end of the lever 11 on which acts in the direction of the arrow 19 the force of a spring 20 centered by

discs

21 and 22 round the screw 17 mounted by its lower end into an angle 23 fastened by screws 24 to the base plate. The stress of the spring 20 may be adjusted after loosening of the screws 24 by a vertical motion of the angle carrier 23, for which purpose the carrier 23 has vertical adjusting cut-outs 25 for the fastening and adjusting screws 24. The nut 18 on the screw 17 limits the motion of the right end of the lever 11 in the upward direction under pressure of the spring 20 in such way that this limiting is also effective in case the tube 1 does not rest on the lower sealing supports, i.e., for example in case the tube 1 is for the purpose of filling deviated from the vertical position shown by full lines to the position 101 drawn by a dashed line. To this position the tube 1, after releasing of the lower connection, is forced by a small force of a fiat pressure spring 26 mounted to the base plate 14 by a screw 27. In position 1 drawn by a dashed line it is possible to suck into the tube 1 the sample and other liquids including bubble pistons. On filling with a liquid from the reservoir 28 the latter is slipped over the narrowed lower end which is submerged below the level of the liquid 29. By a simple manual manipulation it is thus possible at a simultaneous suction through the hose 3 to fill the tube 1 to a certain mark with the appropriate liquids and possibly with gas bubbles; in order to suck in an air bubble it suffices to lower the reservoir 28 so that the opening 2' of the lower end of the tube 1 may be for a required time above the level of the liquid 29. It is, however, possible even without using calibration marks to bring into the tube 1 a predetermined volume of a liquid by connecting the hose 3 for the period of the filling of the tube 1 to a suction device which automatically precisely determines the appropriate volumes.

When the sample tubes 1 are not being filled, they are in position 1, drawn by a full line, where they rest under the pressure of the spring 20, transmitted by the lever 11, on a culfpacking 30 of an elastic and chemically inert material, for example silicon rubber. The cuff 30 is tightly mounted into a packing body 31 into which engages a hollow needle 32 on whose lower end is tightly slid an outlet capillary 33. The packing body 31 is clamped and centered by a bore 34 in the body 35 mounted by connecting screws 351 to the base plate 14. The needle 32 may pass through the central hole of the cuffpacking 30 and possibly even overhang as far as to the narrowed lower opening of the lower end 2 of the tube 1. Thus even when higher pressures are used, a perfectly tight connection between the tube 1 and the hollow needle 32 or the outlet capillary 33 is accomplished. The hollow needle 32 prevents the deformation of the cuifpacking 30 due to greater pressures, which deformation could cause clamping of this cuff 30 and closing of its central hole.

The hollow needle 32 may reach as far as to the capillary cavity of the lower end 2 of the tube 1. In order that on moving the end 2 to the functional position the transmitted force of the spring 20 should not cause crushing or some other damage of the lower narrowed end 2 of the tube 1 or even on the upper end of the hollow needle 32, it is necessary to secure with a relatively great accuracy a sufficiently centric mounting of the lower end 2 of the tube 1 on the cuffpacking 30 and the upper end of the hollow needle 32. This is secured by the cylindrical portion 36 of the cavity of the packing body 31 being precisely centric with the hollow needle which is pressed into the hole in the lower portion of the packing body 31. In order that the lower end 2 of the tube 1 may be safely introduced into the above centering cavity 36, the cavity 36 enlarges conically in the upper portion of the packing body 31. In order to secure a reliable introduction even into the funnel-shaped portion of the packing body 31, the tube 1 is centered roughly in addition by being, after completion of a filling and with the handle 15 of the lever 11 lifted manually against the force of the spring 20, introduced into the cut-out 38 of the angle 39 fastened by a screw 40 to the base plate 14. This preliminary centering takes place automatically simply by the pressure of a finger in the direction of the arrow against the force of the spring 26, bringing the tube 1, which will enter the centering cut-out 38 of the angle 39, to a position where further precise guidance is provided by the

surfaces

37 and 36 of the packing body 31, as the tube 1 is lowered under the transmitted pressure of the spring 20, in case the manual action on the handle 15 of the lever is released. The position of the stop nut 18 is so selected that upon full bearing of the lower end 2 of the tube 1 on the elastic cuff 30 the pressure of the spring 20 may not be eliminated by the hearing of the right end of the lever 11 on the limiting nut 18. The danger of the outlet capillary 33 slipping from the lower end of the hollow needle 32 on possible involuntary actions on this capillary 33 during operation is eliminated by the capillary 33 being in its upper portion, where it is slipped on the lower end of the hollow needle 32, gripped by the lateral pressure of the securing screw 41 on the hollow sleeve 42 which is so cut through along its entire length or at least in its upper portion that it transmits the pressure of the screw 41 on the capillary 33 which is thus clamped by the required pressure against involuntary slipping 0E.

In addition to the represented example, there are many possible alternatives providing similar functions. Thus for example the tube 1 as shown in FIG. 1 can remain permanently stable on the other hand the parts mounted to the plate 14, especially the packing body 31 and the elements connected with it can be moved. Thus the same functional relative positions of the tube 1 and the packing body 31 towards each other can be accomplished.

Both the above and a number of further possible alternatives permit a perfectly tight connection of the sample tube 1 with the tubings, the lower joint being from the point of view of manipulation easily disconnectable for the purpose of filling. The tube 1 may even at greater lengths be dimensioned so as to have a sufficient strut strength. The narrowing of the tube 1 at the lower end is such that on the one hand it does not decrease the strut strength and on the other hand it helps accomplish a great specific pressure on the cuff 30 as it is necessary for a. perfect sealing. In addition to that the narrowed lower end 2 provides a substantially smaller outer surface which is wetted by the sample or by other liquids on filling. On wiping the outer surface, for example with a filter paper, a great accuracy is obtained in limiting the liquid by the lower menisc in the lower opening of the tube 1, this menisc being in so small a diameter of the capillary that even a possible uncertainty in its position (in tenths of mm.) will have a very negligible effect upon the amount sucked in.

As it is evident, optimum conditions are accomplished here for a perfect transfer of a certain amount of sample into the sample tube 1 and at the same time for as perfect as possible a rapid transferring of the sample from the sample tube 1 to the place of processing, for example to the upper end of a chromatographic column. The tendency of liquids to adhere to the inner and outer Walls of the tube 1 which come into contact with the sample and the other liquids may substantially be decreased by a hydrophobization surface treatment, for example by siliconing.

A sample tube 1 of greater length can hold more than one sample with the possibility of each sample being separated from the other ones by means of bubble pistons. The adverse effect of the bubble pistons on the function of a column is practically obviated by the bubble remaining above the upper filling of the column and dissolving in a short time by the action of a deaerated eluent, especially in that case when the bubble is scattered into many small bubbles on passage through a porous body, which effect is used in modern closures of chromat-ographic columns.

The device according to the invention fulfills optimally the conditions of automatic introduction of samples to columns even under difficult conditions given especially by high pressures which occur in especially effective modern methods of chromatographic and similar analyses. But it can also be used even for other purposes, for example for automatic introduction of samples to columns via a pump designed for pumping of eluents. In this case the device is placed in the suction branch of the pump. The conditions of operation are here substantially simpler, especially because the pressure action here is unnecessary.

FIG. 6 exemplifies schematically a version using a long sample tube 102, once or several times bent.

It for whatever reason, for example for a larger volume designed for holding a larger amount of samples or more samples the sample tube must be long, it may be bent several times and clamped not by its upper end but near its lower end 2 by means of grips. A design is represented where the sample tube 102 is bent twice and held near its lower end by two

grips

43 and 44 fixed to the base plate 14. In order to secure that the tube 102 will not slip through the grips, it may have one or more lugs 45 fixed thereto. The design according to FIG. 6 is an example of the above-given second possible version where the tube 1 is stable and movable are on the contrary the parts that secure a tight connection of the lower end of the tube with the outlet capillary 33. The members marked with the same reference marks have the same function and significance as in FIGS. 1 to 5. However the lever 11 according to FIG. 6 can swing round the joint 12 fastened in a holder 46 fixed by means of screws 47 to the base plate 14. A swinging lever 48 for transmitting the force of the spring 20 acting in the direction of the arrow 49 transmits the force by means of a joint 50 to a pull rod 51 on which is mounted a holder 35 which carries the packing body 31 forming in principle the releasable connection with the outlet capillary 33, the sealing proper and the linking of the tubing being identical with the case according to FIGS. 1 to 5. By pressing the left end of the lever 48 against the force of the spring 20 it is possible to release the above joint. The pull rod 51 swings after release with the parts mounted on it by the effect of a weak spring 26 to position 510 represented by a dashed line. Thus the lower end 2 of the stable sample tube 1 is released and individual liquids can be sucked on into the tube as according to FIG. 1. The swing of the pull bar 51 is limited by a stop formed conveniently by an adjustable screw 52. After the sample has been sucked into the sample tube 1 it is necessary that a tight connection be renewed between the lower end 2 of the tube and the capillary 33. In order that this may particularly conveniently be realized merely by the pressure of one finger, the lever 48 is connected by means of a point 53 to a further lever 54 of the shape represented which passes as well as thelever 48 through a hole in the base plate 14. If the pressure of the finger, while the connection of the tube 1 with the capillary 33 is being closed again, acts instead of on the end of the lever 48 on theen-d of the lever 54, then this pressure reduced in the ratio of the lengths of the respective arms will eliminate the force of the compression spring 26. Thus the pull rod 51 will be made to turn against the force of the spring 20, with all the parts mounted on it, round the joint 50 back to the fully drawn position in which acts an approximate centering by fitting of the tube 1 into the cut-out 38 of the guidance 39 and a precise centering takes place by the effect of the funnel-shaped guidance for the end 2 of the tube 1 in a manner identical with FIG. 5.

An example of connection of the tubes 1 into the pressure circuit is schematically shown in FIG. 7. The sample tubes 1 in a larger number, for example six, are arranged parallel so as to form a battery of tubes 1 represented in FIG. 1 by two tubes. After filling, the individual sample tubes 1 are connected by their lower ends subsequently via a multiway distributing valve 55 to the capillary tubing 56 leading to the column 57. The eluent is forced simultaneously into all the sample tubes 1, except the one which is possibly just being filled by means of the pump 58 whose discharge side is connected by means of a tubing 59 to the upper distributing valve 60. This valve 60 is so arranged that normally the tubing 59 communicates by means of a circumferential groove 61 with all individual sample tubes 1 by means of a connecting hose 3. However, flow occurs only through that tube 1 whose outlet tubing 33 is interconnected to tubing 56 by a channel 62 in the spindle of the distributing valve 55. The circumferential groove 61 of the upper valve 60 is interrupted by a bridge 63 in which opens a channel 64. If the spindle of the valve 60 is so turned that the channel 64 communicates with a certain one of the branches 65 to which are connected individual hoses 3, then this branch and the hose and also the respective sample tube 1 are disconnected from communication with the tubing 59 and the pump 58. On the other hand one of the sample tubes I communicating with the channel 64, which at the same time permanently communicates With the tubing '66, can be filled in such way that, using the above-given manipulations, the connection of the sample tube 1 with the respective outlet capillary 33 is released, whereby filling is accomplished with the lower end of the tube disconnected by suction by means of a suction tubing 66 which through the channel 64 communicates with the respective connecting hose 3 leading to the particular sample tube 1 which is just being filled.

After subsequent filling of all individual sample tubes 1 all the tubes are connected to the delivery tubing 59 of the pump 58 by the spindle of the upper distributing valve 60 being so turned that the bridge 63 is between any two circumferential branches 65.

What I claim is:

1. An arrangement for transferring dosed samples, particularly for automatic analyzers comprising at least one sample tube, a distributing valve, a discharge tubing, means for connecting one end of said sample tube with said distributing valve, the other end of said sample tube adapted to be connected with said discharge tubing, means for sealing the connection between said other end of the sample tube and the discharge tubing and means for imparting a relative movement between the second end of the sample tube and the discharge tubing so as to allow alternately free access to this other end of the sample tube, and to accomplish a tight coupling between the sample tube and the discharge tubing.

2. An arrangement as in claim 1 comprising a spring loaded lever system supporting the sample tube and urging the same into tight connection with said discharge tubing.

3. An arrangement as in claim 1 comprising a spring loaded lever system supporting the discharge tubing and urging the same into a tight connection with said sample tube.

4. An arrangement as in claim 1 comprising a tight connection-made of a yieldable material between the end of the sample tube and the discharge tubing; and a hollow needle passing through said yieldable material, said needle extending into the sample tube and being connected to the discharge tubing.

7 8 5. An arrangement as in claim 1 comprising guiding v ,7 References Cited means securing the correct relative position of the sample UNITED STATES PATENTS tube and the discharge tubing.

'6. An arrangement as in calim 1 comprising a distri- 2,757,541 8/1956 Watson et 73-422 buting valve connecting said sample tube and said pump 5 2,448,206 3/1948 Bailey 23 254 to cause sucking of the sample into the sample tube. S CLEMENT SWISHER, Acting Primary Examiner.