Apparatus for sample handling for an injection system of a chromatograph

The invention relates to an apparatus for sample preparation and/or sample delivery for an injection system of a chromatograph, having a magazine (1), which can be moved in steps, for juxtaposed sample tubes (2), and having a lifting device (6) which can be moved between two end positions perpendicular to the transport direction of the magazine (1) via a motor (11) and bears a gripper (7) for a sample tube (2), as well as having a transfer device for a sample tube (2), the lifting device comprising at least one telescopic threaded cylinder (8) which bears the gripper (7) and has a plurality of nested threaded cylinders with an inner threaded cylinder (8a) and an outer threaded cylinder (8d) of which one is arranged non-rotatably relative to the magazine (1), while the other can be rotated by the motor (11).

FIELD OF THE INVENTION

The invention relates to an apparatus for handling samples for an injection system of a chromatograph for at least one of handling action of the group of sample preparation and sample delivery. Such a sample delivery apparatus serves the purpose of extracting sample tubes from a magazine and transferring them into an injection system of a chromatograph, for example a liquid or gas chromatograph.

BACKGROUND OF THE INVENTION

It is known that samples contained in the sample tubes can, for example, be subjected there to thermodesorption as described, for example, in German Patent DE 44 19 596 C1. After the extraction of the sample tubes from the magazine, the former have to be lifted out of the plane of the magazine. It is known for this purpose to provide a lifting device which can be adjusted between two end positions and has a holding device for a sample tube. The lifting device is formed in this case by a motor-operated shearing mechanism. However, the latter is sensitive and not very stable and therefore liable to failure.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide a robust and strong apparatus for handling samples for an injection system of a chromatograph.

Thus, the invention concerns an apparatus for handling samples for an injection system of a chromatograph in the form of sample preparation and/or sample delivery, said apparatus having a magazine, which is moveable in steps, for juxtaposed sample tubes, and having a lifting device which is moveable between two end positions perpendicular to the transport direction of the magazine via a motor and bears a gripper for a sample tube, as well as having a transfer device for a sample tube, wherein the lifting device comprises at least one telescopic threaded cylinder which bears the gripper and has a plurality of nested threaded cylinders with an inner threaded cylinder and an outer threaded cylinder of which one is arranged non-rotatably relative to the magazine, while the other is rotateable by the motor.

The fact that use is made of a lifting device which comprises at least one telescopic threaded cylinder which has in each case a plurality of nested threaded cylinders, of which the inner threaded cylinder is arranged non-rotatably, while the outer threaded cylinder can be rotated by motor, results in a stable and robust design which is correspondingly not very liable to failure.

When two mutually spaced telescopic threaded cylinders are used, their outer threaded cylinders can be driven synchronously for a parallel movement, or asynchronously for an angularly displaced movement.

Further embodiments, objects and advantages of the invention are to be gathered from the following description and the claims.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The apparatus illustrated inFIG. 1comprises a magazine1which can be moved horizontally (perpendicular to the plane of the paper inFIG. 1) and in steps, and which accepts sample tubes2by means of clamps3parallel to one another traverse to the direction in which the magazine1can be moved and in a horizontally arranged fashion. Arranged next to the apparatus is a thermodesorption device4of a gas chromatograph into which sample tubes2are inserted successively from the magazine1, and whose samples are subjected to a thermodesorption, after which the sample tubes2are subsequently transported back into the magazine1.

The apparatus comprises a lifting device6, arranged on a plate5, with a gripper7for a sample tube2.

In the exemplary embodiment illustrated, the lifting device6comprises two telescopic threaded cylinders8which are arranged at a spacing from one another and in each case have a plurality of, four in the case illustrated, nested threaded cylinders8a,8b,8c,8dwhich engage with one another via balls in order to be as easy to move as possible. Because the gripper7is fastened on the respectively inner threaded cylinders8a, they are arranged non-rotatably relative to the plate5. The respectively outer threaded cylinders8dare provided on their outer circumference with a toothed rim9such that they can be driven jointly and therefore synchronously via a toothed belt10by an electric motor11with the aid of a downstream transmission.

Instead of the outer threaded cylinder8d, it is also possible for the inner threaded cylinder8ato be driven while the outer threaded cylinder8dis stationary.

If only one telescopic threaded cylinder8is used, the inner threaded cylinder8ais to be held non-rotatably relative to the plate5via, for example, a guide rod guided non-rotatably in the plate.

It is, furthermore, expedient, particularly in the case where not only the two end positions of the gripper7, but also at least one position lying therebetween are to be capable of being driven, to provide on the plate5a rotation angle sensor12for monitoring the extension of the telescopic threaded cylinders8. Fastened by suspension on the gripper7is an extractable transmission belt13of the rotation angle sensor12, whose extracted length constitutes a measure of the extension of the telescopic threaded cylinders8.

Located on the plate5is a printed circuit board14with electric components for controlling the movement of the lifting device6and of the gripper7. This also includes trimmers15corresponding in number to the number of the positions which the lifting device6is to approach and which can be set via the trimmers15.

The gripper7comprises an elongated rail16which is fastened on the inner threaded cylinders8aand bears on the underside an electric motor17via a holder17a. Two gripper clamps18projecting over the rail16are suspended opposite to one another on the rail16and are biased in the opening direction via a plurality of U-shaped spring sheets19, that is to say the spring action of the limbs of the spring sheets19is directed outwards. Arranged on the rail16is a microswitch20which is actuated by a sample tube2picked up by the gripper7. In such a case, the microswitch20triggers the electric motor17, whose shaft21bears a locking device in the form of a plate22with pins23. The pins23engage with limbs24which are connected to the gripper clamps18and project into the region of the pins23, one limb24being shorter than the other such that in the open position of the gripper clamps18the limbs abut one another, whereas the pins23can engage separately with the two limbs24, compare, for example,FIG. 6a. The gripper clamps18are brought into engagement with a sample tube2located therein by rotation by 90°, and held, compare, for example,FIG. 4or6d.

The spreading device can also comprise a cam disc.

A transfer device for transferring a sample tube2gripped by the gripper7comprises a locking cone25which can be moved in stages in the longitudinal direction, for example by means of a guided carriage, a spindle or the like, and has seals, compareFIGS. 5a,5b. The locking cone25accepts an end of the sample tube2held by the gripper7, whereupon the gripper7opens and releases the sample tube2for further transport into the thermodesorption device4, whose valve head receptacle26is shown inFIGS. 5a,5b. In this case, the lifting device6moves back into the initial position so that the locking cone25can pass.

The cycle of motion of the lifting device6and of the gripper7is illustrated in steps inFIGS. 6ato6g. In accordance withFIG. 6a, the lifting device5is in its lower retracted position. The gripper7is open. The magazine1is moved one step further and thus over the gripper7such that a sample tube2is located above the latter,FIG. 6b. The lifting device6is raised into an intermediate position in which the sample tube2is picked up by the gripper7and actuates the microswitch20,FIG. 6c. The latter initiates a 90° rotation of the electric motor17and thus a closure of the gripper7, which is held in this position,FIG. 6d. Thereafter, the lifting device6is raised into its upper end position,FIG. 6e. The sample tube2is gripped by the locking cone25at one end and the gripper7is opened by the electric motor17,FIG. 6f. The lifting device6moves into its lower end position, so that the locking cone25can pass.

After the thermodesorption has been undertaken, the sample tube2is recovered in the opposite direction and deposited in the magazine1, after which the entire operation is repeated.

Instead of a thermodesorption device4, it is also possible to use any other desired injection device for a chromatograph or a sample preparation apparatus into which and from which sample tubes2can be introduced and removed.

In accordance withFIGS. 7,8, the sample tube2is bonded in a metal positioning tube27which simultaneously accepts a carrier gas tube28, coaxial therewith, via a sealing cone29and a spacing sleeve29aat one end, and a receptacle30, connected to the carrier gas tube28by bonding, for example, for the locking cone25at the other end. The receptacle30projects from the positioning tube27in order to be able to be brought into engagement with the locking cone25in a sealed fashion. The sealing cone29is seated in the sample tube2. Moreover, the sample tube2has a pressure plate31, provided with a small through-opening, on its side averted from the locking cone25. Upon being inserted, for example into a heatable tube32of the thermodesorption device4, the said pressure plate presses against a spring34held by a connecting piece33, as a result of which the seal between the sample tube2and carrier gas tube28is ensured during the thermodesorption. A receptacle26of the thermodesorption device4is provided with a bore35for supplying the carrier gas which communicates with a bore36in the locking cone25from which supplied carrier gas passes into the carrier gas tube28in order to lead off desorbed substances through the connecting piece33.

In accordance withFIGS. 9,10, the carrier gas tube28fills up the positioning tube27and is provided with a circumferential groove37where the positioning tube27is flanged in. The locking cone25thereby directly holds the carrier gas tube28.

In the embodiment illustrated inFIGS. 11,12, the seal29embraces the sample tube2conically, on the outside. For this purpose, the carrier gas tube28has a projection28aonto which is pushed the seal29, which embraces the end of the sample tube2with its sealing cone.

The seal29effects a gas-tight connection between the sample tube2and carrier gas tube28such that no ambient flow takes place on the outer circumference, as a result of which contaminants, such as fingerprints, located on the outer surface cannot impair the sample analysis.

Consequently, it is possible for different sample tubes2to be handled with the aid of the same apparatus by using a positioning tube27.