US3550453A - Automatic liquid sampler - Google Patents

Description

7 a G. E. LIGHTNEl ETAL 3,55%3

AUTOMAT I C LIQUID SAMPLER Filed March 5, 1969 Sheets-Sheet 1 mvmltrms G 6116 E. I, iqhhwr BY Howard lziMulzlzsifii z' ATTURNETIS Dec. 29, 1970 E. LIGHTNER ET AL 3,550,453

AUTOMATIC LIQUID SAMPLER 2 Sheets-Sheet 2 Filed March 5, 1969 INVENTOBS Gene EL Howard B. W611" WW z/fflgd ATTORNDS United States Patent O 3,550,453 AUTOMATIC LIQUID SAMPLER Gene E. Lightner, Kennett Square, PE!., and Howard B.

Muhlestein, Wilmington, DeL, assignors to Hewlett- Packard Company, Palo Alto, Calif., a corporation of California Filed Mar. 3, 1969, Ser. No. 803,634 Int. Cl. G01n 1/14 US. Cl. 73--422 1 Claim ABSTRACT OF THE DISCLOSURE A syringe is mounted with its needle aligned with the entrance of a sample receiving chamber. The syringe is moved along its axis into and out of the sample receiving chamber. A sample rack is positioned to successively introduce each of a plurality of sample containers to a sampling location in the path of movement of the syringe needle. The syringe and syringe plunger are automatically operated to withdraw a sample from the container, await the removal of the container from the path of movement and then introduce the sample into the receiving chamber. In an alternative embodiment, the sample containers are constructed with a double aperture, each aligned with the path of movement of the syringe needle so that the syringe needle may be introduced first into the container and then passed through the sample container to introduce the sample into the sample chamber.

BACKGROUND OF THE INVENTION This invention relates to an improved automatic fluid sampler and, more particularly, to an automatic fluid sampling system which mechanizes a syringe to transfer sample aliquots from any of a plurality of sample vials to a receiving chamber.

With the increased cost of the utilization of direct manpower for performing analyses using gas chromatographs and other analytical instruments, it is becoming economically desirable to provide both semiand fully automatic systems for performing such analyses. Two of the most time consuming functions for the analyst are sample injection into the gas chromatograph, or other analytical instrument, and data interpretation and quantization. Integrators, multiplexers, A/D converters, and computers allow substantial savings in these latter areas. Unfortunately, however, full automation still awaits the development of a versatile, reliable automatic samplerinjector. This automatic sampler-injector should be capable of extracting a precise sample of a fluid to be analyzed from a sample container and inject the same into the analytical instrument.

In the case of gas chromatography several such systems have been developed. One of these systems utilizes a rotating valve having a number of sample volume ports. The rotating valve is rotated to position these ports successively into a conduit leading to the gas chromatograph injection port. A volume of wash solvent may be used to flush the total sample into the injection port. Unfortunately, such systems have encountered problems. Among these problems have been the solvent peak showing up in the resulting chromatogram, leaks between the adjacent ports resulting in contamination of the sample, and, finally, the apparatus has required careful cleaning by hand after each use.

Other techniques have envisioned vapor rather than fluid sampling. These require that the liquid sample be vaporized and the vapor sampled with a conventional gas sampling valve. This technique is workable but is ac- 3,550,453 Patented Dec. 29, 1970 "ice companied by the problems of temperature and pressure control of the sample. Without relatively precise temperature and pressure control, sample sizes tend to vary resulting in inaccuracies of the analysis. Cleaning has also been a problem.

Still other techniques have envisioned utilizing a low melting point sample tube made of an alloy. The liquid sample is loaded into a tube and the tube ends crimped. The tubes are loaded into an automatic rotating feeder which injects the tubes into a heater where the tube is melted and the sample vaporized. Unfortunately, this technique has resulted in wide variation in sample size and considerable manpower is required to load the sample tubes in the first instance. Furthermore, the different melting rates of the tubes produces variations in the temperature programmed analyses. Other techniques such as the use of preloaded syringes has also been proposed but is accompanied by problems in the successful implementation thereof.

It is an object of this invention to provide an improved automatic fluid sampling system.

Another object of this invention is to provide an improved mechanized syringe capable of transferring samples from a plurality of sample containers to a receiving chamber.

BRIEF DESCRIPTION OF THE INVENTION In a preferred embodiment of the invention an automatic sampling system is adapted to successively transfer a fluid sample from any of a plurality of fluid sample containers to a sample receiving chamber. The sample chamber and each of the sample containers have an inlet aperture which may be closed by an elastomeric material. A positioning means successively shifts each of the sample containers to a sampling location at which the inlet apertures of the container and the sample receiving chamber are in axial alignment. To effect the transfer, a fluid transfer tube, such as a syringe, is shifted by a suitable actuating means along the axis of aperture alignment between a rest position, the sample container at the sampling location, and the sample receiving chamber. In one embodiment of the invention the sample container is withdrawn from the path of fluid transfer tube movement to permit the transfer tube to reach the sample chamber. In another embodiment the sample container is double ended to permit the transfer tube to stop its axial motion long enough to withdraw a sample from the container, then penetrate the remaining wall of the container to transfer the sample into the receiving chamber.

BRIEF DESCRIPTION OF THE DRAWINGS The novel features that are considered characteristic of this invention are set forth with particularity in the appended claim. The invention itself, however, both as to its organization and a method of operation as well as additional objects and advantages thereof, will best be understood from the following description when read in connection with the accompanying drawings in which:

FIG. 1 is a front elevation view of the automatic sampling system of the invention using a syringe positioned to inject a sample into the injection port of an analytical instrument;

FIG. 2 is a side elevation view of the automatic sampling system shown in FIG. 1;

FIG. 3 is a bottom view of the automatic sampling system illustrated in FIG. 1;

FIG. 4 is a schematic illustration denoting a typical sequence of movements of the syringe in the automatic sampling system illustrated in FIG. 1;

FIG. 5 is a schematic drawing of an alternative embodi- 3 ment of the automatic sampling system of this invention in a first position of operation;

FIG. 6 is a schematic drawing illustrating the alternative embodiment illustrated in FIG. in a second position of operation; and

FIG. 7 is a schematic illustration of the alternative embodiment of FIG. 5 in a third position of operation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiment of the invention illustrated in FIGS. 1 to 3, inclusive, mechanizes the operation of a fluid transfer tube 18. The fluid transfer tube is illustrated as a syringe having a barrel 24, a plunger 22 and a needle 16. In the alternative any pump actuated conduit may be used. The mechanization is such that the syringe 18 moves up and down (in the drawing) along the axis of the barrel. This permits the syringe needle 16- to penetrate the cap or septum 144 of a sample vial or container 142 po sitioned on the axis of the syringe movement. The sample containers 142 are held in a sample rack or turntable 140 which will be described hereinafter. The operation of the sample rack 140 is to successively position different sample containers into a sampling location (the axis of the syringe). The assembly which includes the syringe 18 and the sample container 142 is positioned such that the axis of the syringes movement is in alignment with the entrance aperture 11 of a sample receiving chamber (sample inlet) of a gas chromatograph or another analytical instrument 14. In the event that the instrument is a gas chromatograph the injection port or sample inlet is typically closed or sealed by a septum formed of an elastomeric material usually held on by a cap nut. The syringe 18 is operated to withdraw a fluid sample from the sample container 142, the sample container is then removed from the axial path of movement of the syringe, the syringe inserted into the sample inlet 10, and the sample fluid contained therein transferred or injected into the analytical instrument. The syringe is then withdrawn and another sample container 142 is positioned at the sampling location.

The structure by which this embodiment is implemented will not be described. The entire structure illustrated is positioned over the sample inlet or injection port of the analytical instrument 14 such that the axis of the barrel intersects the sample inlet 10. Although the mounting is illustrated to be vertical, it is to be understood that the syringe may be positioned to operate in a horizontal manner if desired to operate in conjunction with a horizontally disposed sample inlet. Further the mounting of the sampling structure to the instrument may be accomplished by any suitable means such as bracket 15.

The syringe 18 is mounted in an assembly for moving the syringe barrel up and down and also operating the plunger using a mechanism of the type described in an earlier application Ser. No. 760,538 filed Sept. 18, 1968, by Lightner et al. As is described in the said Lightner et al. application, the barrel of the syringe 18 may be held in a two piece, adjustable width, U-shaped bracket 24. The U-shaped bracket is made adjustable by the use of a sliding member secured by an adjusting screw which engages a slot formed in the sliding member. The adjustable width permits the accommodation of different size syringes. Appropriate concave indentations are formed on the inner surface of the upright portions of the U-bracket 24 to securely position either end of the barrel. The plunger 22 is inserted through a slot in one of the uprights.

The U-bracket 24, which supports the syringe 18 is secured to the end of the piston of an actuating means designated the barrel prime mover 82. The barrel prime mover 82, as all of the prime movers described herein, may be of any suitable type such as a servo motor. A particularly preferred prime mover, however, is one capable of providing a linear or displacement motion un der the actuation of a digital signal. One prime mover of this type which has been utilized successfully is a pneumatic cylinder which includes the piston, a cylinder 86, and an input air nipple 84 through which a compressed gas is passed to provide the motive power for the piston. The lower end of the cylinder 86 is secured, as by a support clamp 90 attached as by screws 92, to a support frame 94. The support frame 94 is in the form of an L- shaped bracket (extending rearwardly in FIG. 1) which also supports a shifting means or sample rack prime mover 96. The sample rack prime mover 96 includes a piston 98 and a cylinder 100 which operates the piston. The piston is operated by gas pressure applied to the cylinder 100 through a suitable nipple 102 as seen only in FIG. 3.

The sample rack 140 is generally disc shaped and is generally journaled onto a rod 104 secured to a sliding bed 106 which is adopted to slide within adjustable V- guides 108 thereby to position the sample rack 140 into and out of alignment with the syringe barrel 18. The adjustable V-guides 108 are secured to the L-bracket 94 as by screws (not shown). An adjustment screw 110 permits the degree of sliding freedom of the bed 106 to be controlled. A forward stop 112 in the adjustable V-guides 106 limits the forward motion of the sliding bed 106. The piston 98 is connected by a suitable hitch 114 to operate the sliding bed in the manner described.

The turntable is illustrated as being generally discshaped and has a circular row of apertures 141 formed in the peripheral surface thereof. The fluid vials or sample containers 142 are shaped to fit within the apertures 141 as perhaps most clearly seen in FIG. 3. The cap portion 144 of the containers 142 extends outwardly from the sample container to thereby form a flanged portion which prevents the sample containers from falling through the slots which form the apertures 141. As described in said Lightner et al. application, a retaining arm (not shown) may be mounted to the turntable mounting rod 104 to a position partially covering the top edges of the septums 144 at the sampling location of the syringe. This prevents the sample containers from being dis lodged during the syringe operation. The upper portion of the sample rack 140 is flanged as at 146 to provide a limit stop for the downward motion of the syringe 18. As may be noted in the phantom illustration 148 of FIG. 2, the flanged portion 146 extends sufliciently to engage the U-shaped mounting bracket 24.

The apertures 141 are open at the outer peripheral surface of the turntable to facilitate indexing the successive sample containers 144 to the sampling location of the syringe 18. While the indexing of the turntable may be achieved by any suitable means, such as an electric servo motor or other drive mechanism, the digital actuator described by said Lightner et al. is preferred. This digital actuator permits the entire sampler to be operated under the control of digital impulses. The details of this actuator are most clearly seen in FIGS. 2 and 3. It includes an indexing prime mover 150 which may be a pneumatic cylinder of the type described having a barrel 152, a nipple 154 for the admission of gas pressure and a piston 156. The piston drives an indexing arm which engages each of the exposed peripheral slots of the apertures 141. Thus each time the indexing prime mover 150 is energized, the indexing arm 160 extends outwardly causing the turntable to rotate incrementally in a clockwise sense.

To aid in properly locating the sample containers 142 at the sampling location of the syringe 18, an indexing roller 172 is attached to a clamp 151 which is secured to the V-guide 108 which clamp holds the indexing prime mover 150.

Although not shown for the sake of clarity of illustration, the several prime movers are each actuated by separate gas pressure lines connected to the respective nipples 84, 52, 102, and 154. These nipples are connected through lines which are separately energized by valves under the control of a digital actuator or programmer. For example, the valves are each actuated by an electrical signal derived from an output of a punched tape reader on which the desired operating program of the sampler is stored.

The plunger 22 of the syringe 18 is actuated by a plunger prime mover 44 which is secured to a side projection 40 on the U-bracket 24. This side projection 40 has a portion which is bent forwardly as may be seen most clearly in FIG. 2 to form a side arm 42 to which the lower end of the barrel portion of the plunger prime mover 44 is secured as by a nut 47. The barrel cylinder has an air nipple 52 by which the piston 48 is energized to move upwardly in the drawing and thereby withdraw the plunger 22 from the syringe barrel. This is accomplished by the use of an L-shaped bracket 60 secured to the end of the piston 48 as by a pair of nuts 62. The L-shaped bracket 60 extends along the side of the barrel and mounts a clip 64 which engages the plunger thumb disc or the clip may be secured to the plunger itself as by a set screw or other suitable mechanism. The side arm 42 of the U-bracket 24 has a screw 70 inserted therethrough which extends through a slot 72 in the L-bracket 60 to act as a guide for the axial motion of the L-bracket when the plunger prime mover is actuated. A knurled nut 74 on the screw 70 may be turned to adjust the length of the plunger stroke by limiting the return stroke permitted of the piston 48. The back portion of the L-bracket 60 has a projection 61 adapted to engage a vertically disposed guide slot 63 in the bracket side arm 40 to prevent rotation of the L-bracket 60 as it is moved by the plunger prime mover 44.

In a typical sequence of operation as may be seen in the sequence of FIG. 4 the indexing prime mover 150 is actuated to position a new sample container 142 into the sampling location (the axis of alignment between the downward motion of the syringe barrel and needle into the sample inlet chamber Thus in position, the barrel prime mover 82 is energized such that the syringe 18 is moved downwardly in the drawing (sequences 2-3), as denoted by the phantom illustration 148 (FIG. 2), to introduce the syringe needle 16 through the cap 144 of the sample container 142. The flange 146 limits the downward movement of the syringe. Next the plunger prime mover is energized to withdraw the plunger and hence some of the fluid sample in the container 142 into the syringe. Actually the plunger 22 may be moved up and down several times by the operation of the plunger prime mover 44 to insure that air bubbles are removed as described in said Lightner et al. invention. The barrel prime mover 82 is deenergized permitting its spring return to withdraw the needle 16 from the sample 142 and return to the up position (sequence 4). Next the sample rack prime mover 96 is energized to withdraw the sliding bed and hence the turntable 140 from its position of alignment with the sampling location (sequence 5). The barrel prime mover 82 is again actuated and the syringe needle 16 allowed to extend all the way down into the sample inlet 10 (sequences 6 and 7). The flange 146 on the sample rack no longer prevents this downward movement since it is withdrawn. With the needle penetrating the sample inlet 10, the plunger prime mover 44 is operated to discharge the sample. To complete the cycle the barrel prime mover 82 is deenergized such that the syringe is withdrawn from the sample inlet 10. The index prime mover 150 then advances a new sample container to the sampling location and the sample rack prime mover 96 returns the turntable to the sampling location which is the home position illustrated in FIG. 4. In this home position, as will be noted, the sample container lies on the axis of alignment between the syringe needle and the sample inlet.

'An alternative embodiment of the invention is illustrated schematically in FIGS. 5, 6 and 7. In this embodiment all of the structure is substantially the same as that previously described. The essential difference lies in the fact that the sample containers 200 are modified to be in the form of a hollow tube with either end forming an aperture which is covered by an elastomeric material such as rubber or other suitable septum material 202. Further more, the lower end of the peripheral apertures 141 is opened at 204. This permits the syringe needle 16 to penetrate the upper cover 202, sample some of the fluid stored in the container 200 and then pass on through the lower cover 202 through the orifice 204 into the sample inlet 10, at which point the sample is discharged. The only other modification to the system of FIGS. 13 to achieve this result is to remove the blocking flange 146 from the top of the sample turntable and to allow the sample turntable to rotate only, i.e., the sample rack prime mover 96 is not used to shift the turntable. Instead, the sample rack prime mover 96 may be used to operate a blocking member 246 which impedes the downward movement of the syringe 44 to a point that stops the needle 18 within the sample container 200. Alternatively, this may be achieved by the use of two serially connected prime movers and actuating only one of the two prime movers to create the half-way downward movement.

In the sequence of operation beginning with the rest position illustrated in FIG. 7 the syringe barrel prime mover 82 moves the syringe needle 16 downwardly until it is impeded by the shifted blocking member 246 to prevent further downward movement of the syringe. The plunger 22 of the syringe 18 is now operated to withdraw a sample from the sample container 200 as seen in FIG. 5. Next the blocking member 246 is withdrawn by deenergizing the prime mover 96. The downward movement of the syringe may continue, penetrating the lower portion of the vial and entering the sample inlet 10. The plunger 22 is again operated to discharge the sample in the sample inlet and the syringe allowed to return to the rest position illustrated in FIG. 7.

It is obvious that many embodiments may be made of this inventive concept and that many modifications may be made in the embodiments hereinbefore described. Therefore, it is to be understood that all descriptive matter herein is to be interpreted merely as illustrative, exemplary and not in a limited sense. It is intended that various modifications which might readily suggest themselves to those skilled in the art be covered by the following claim as far as the prior art permits.

What is claimed is:

I An automatic sampling system for successively transferring a fluid sample from selected ones of a plurality of fluid sample containers to a sample receiving chamber, said chamber and each of said containers having an inlet aperture, said system comprising, in combination:

positioning means for successively positioning each of said sample containers to a sampling location at which the inlet apertures of said container at said sampling location and said chamber are on the same axis,

a syringe having a needle and a plunger, said syringe having a longitudinal axis aligned with the axis of said inlet apertures, said needle being disposed for passage through said apertures,

first actuating means for shifting said syringe along said aperture axis between a rest position contiguous to sa1d sampling location, a sample container at said sampling location, and said sample receiving chamber, thereby to permit the transfer of a fluid sample from said container to said receiving chamber, and

second actuating means for shifting each said sample container at said sampling location into and out of said aperture axis, thereby to facilitate unobstructed movement of said syringe to and from said sample receiving chamber,

said first actuating means including:

stop means for limiting the axial movement of said syringe needle to engage said container at said sampling location, and

means for operating said plunger to withdraw a fluid sample from the container then at said sampling location and discharge said sample into said chamber after said container is shifted out of alignment with said aperture axis.

References Cited 2/1967 Leslie 7364.1

12/1968 Rochte et a1. 73423(A)X 5/1969 Cruz 73-423 (A) FOREIGN PATENTS 12/1967 France 73422(GC) US. Cl. X.R.

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