Abstract:
The invention relates to a sample handling device for an analytical device, comprising a sampler provided with a holder, a movable holding arm for the holder and a support for the holder, said support being arranged in a stationary manner with respect to the holding arm, said holder being transferable between a suspended position on the support and a position located on the holding arm and being releasable from the holding arm by a pulling force exerted by the holding arm substantially perpendicular to the longitudinal direction of the latter.

Description:
FIELD OF THE INVENTION 
   The invention relates to a sample handling device for an analytical instrument, in particular a chromatograph. Such a device is used to take, prepare and handle samples to be anally by a chemical analysis unit which may be provided with a separation device for sample components like a chromatograph, especially a gas chromatography. 
   BACKGROUND OF THE INVENTION 
   Sample preparation and injection devices, called autosamplers, are known for chromatographs, in particular gas chromatographs. These autosamplers comprise a holding arm which can be moved in three mutually perpendicular directions for a holder of a sampler. Autosamplers of this type are designed for a predetermined, simple sequence, for example sampling by means of a syringe from a vial and discharging the sample into a sample discharge system of an analytical instrument, and a type of samplers provided for this sequence, for example syringes of a specific size. They can neither be used flexibly nor used for other types of samplers without manual conversion. In order to permit a more complicated sequence, it is known to arrange two autosamplers one above the other, each of which is then used for a predetermined programme sequence. However, this is firstly complicated and secondly substantially more complex in terms of the programme sequence. Arrangements of this type are also restricted to two autosamplers and therefore also to two types of samplers, because of the necessary lifting heights. 
   SUMMARY OF THE INVENTION 
   It is therefore an object of the invention to provide a sample handling device which permits substantially more flexible automatic handling of different samplers. 
   A further object of the invention is to provide a sample handling device with little expenditure on equipment. 
   A still further object of the invention is to provide a sample handling device of a simplified construction. 
   The invention thus relates to a sample handling device for an analytical device, comprising a sampler provided with a holder, a movable holding arm for the holder and a support for the holder, said support being arranged in a stationary manner with respect to the holding arm, said holder being transferable between a suspended position on the support and a position located on the holding arm and being releasable from the holding arm by a pulling force exerted by the holding arm substantially perpendicular to the longitudinal direction of the latter. 
   Because a plurality of holders arranged to be stationary in relation to a holding arm are provided, it being possible for the latter for example to be moved in three mutually perpendicular directions, as a result of the fact that the holder in each case for a sampler can be transferred between a suspended position on one of the supports and a position located on the holding arm, it being possible for the respective holder to be released from the holding arm by a pulling force exerted by the holding arm substantially at right angles to the longitudinal direction of the latter, automatic handling of different samplers, which are each held by a holder, can be carried out. By means of suitable software, a programme sequence with regard to sample preparation, sampling, sample discharge, transferring samples or samplers between various stations and/or for preparing samplers can proceed automatically, including the holder change, in a task-specific manner by using different samplers, which can be exchanged with their associated holder. 
   The sample handling device can also serve as a robot for the automation of thermodesorption sequences, in which samples are picked up by a carrier and these are then introduced into a thermodesorption device, where the samples are thermodesorbed and subsequently analysed, for example by gas chromatography. 
   Further objects, embodiments and advantages of the invention can be gathered from the following description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be explained in more detail below with reference to exemplary embodiments illustrated in the appended drawings. 
       FIG. 1  shows, schematically in plan view, a sample handling device of the invention usuable for a gas chromatograph. 
       FIG. 2  shows, as a detail, a front view of a holding arm of the sample handling device of  FIG. 1 . 
       FIG. 3  shows a needle guide holder of the holding arm in section. 
       FIG. 4  shows a needle guide in plan view. 
       FIGS. 5 and 6  show, in side view and as details, the holding arm and a holder for a holder of a sampler. 
       FIGS. 7 and 8  show the holder according to  FIGS. 5 ,  6  additionally in plan view and front view. 
       FIG. 9  shows, in side view, one embodiment for handling a sample tube. 
       FIG. 10  shows, in section, a further embodiment of a needle guide device. 
       FIG. 11  shows a plan view of the needle guide device from  FIG. 10 . 
       FIG. 12  shows, in section, an additional embodiment of a needle guide device. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   The sample handling device shown in  FIG. 1  for a sample analytical instrument such as a gas chromatograph (or a liquid chromatograph, a mass spectrometer or the like) is used for handling samples to be analysed, that it to say for sample preparation, for example by extraction, derivative formation, dilution, stirring, temperature control, admixing reagents or the like, further for sampling from vials  1 , from cells in titration plates or other sample keeping devices, by means of throughflow cuvettes, sample loops, etc., further for sample discharge such as for introducing the respectively taken sample into a sample discharge device of the analytical instrument, further for transferring samples or samplers between various stations and/or for preparing samplers, for example by rinsing. Shown by way of example is the sample handling device for sampling and for introducing the sample taken, for example, above the gas chromatograph, on which there are mounted a large number of vials  1  containing samples in predetermined positions in two groups on corresponding trays. Further stations, for example a rinsing station for samplers, a station for stirring and controlling the temperature of samples, or a station for holding and admixing reagents or the like, can additionally be provided. 
   The sample handling device comprises a horizontal slide guide  2  for a cross slide  3  which can be moved along the slide guide  2  and which, in addition, can be moved in the plane of the slide guide  2  at right angles to the slide guide  2 , so that it is possible to move to all stations. At one end of the cross slide  3  there is a holding arm  4  which can be moved vertically. In this embodiment, a bracket  5  is fixed to the ends of the slide guide  2 , on which bracket, on the side facing the slide guide  2 , supports  6  for samplers  7  are arranged. However, the supports  6  can also be fixed in another way, for example on the gas chromatograph itself. The holding arm  4  may also be a pivot arm, which is accordingly arranged such that it can move. 
   For example, for the purpose of sampling with a sample holder (syringe) change, the cross slide  3  moves the holding arm  4  into a position adjacent to a specific support  6 , removes the sampler  7  there, moves from there over a vial  1  containing the desired sample, lowers the sampler  7  into the vial in order to take the sample, in order then to move the sampler  7  until it is above a (not illustrated) sample discharge device belonging to the gas chromatograph, to introduce the sampler  7  into the sample discharge device and, depending on the type of sampler  7 , either to carry out the sample discharge itself or to place the sampler  7  in the sample discharge device. 
   As can be seen from  FIG. 2 , the holding arm  4  comprises a plate  8  which, for reasons of space, can be provided with a depression  9  opening at the free end of the arm. Arranged above the depression  9  is a vertical guide groove  10  for an actuator  11 , also serving as a piston holder in this exemplary embodiment. The actuator  11  engages in a spindle  12 , which can be rotated by a drive, not shown, in order to move the actuator  11  in the longitudinal direction of the holding arm  4 , that is to say in the vertical direction. The actuator  11  has a holding piece  13  open at the front for the insertion of an actuating head  14  of a sampler formed in this exemplary embodiment as a syringe  16  above a piston rod  15  of a piston of a sampler. 
   A holder  17  of the respective sampler, in this exemplary embodiment of the syringe  16 , can be placed within the depression  9 . The holder  17  comprises a plate  18  which, on the rear, has two sheet metal strips  19  and a plurality of positoning pins  20 . Permanent magnets  21  are let into the plate  8  of the holding arm  4  opposite the sheet metal strips  19 , so that the holder  17  is held by the permanent magnets  21  and is positioned by the positioning pins  20  above the corresponding holes located in the plate  8 . 
   In order to be able to accommodate syringes  16  with different diameters, the plate  18  can carry on the front side a ring  22 , which has crossing passages  23  for this purpose and can be rotated into corresponding latching positions (for example via a spring-loaded ball which interacts with a matching recess in the plate  18 ), in which positions the necessary passage is aligned with the longitudinal direction of the holding arm  4 . Screwed onto the ring  22  is a ring  24 , in order to hold the syringe  16 . In addition, on the front side of the plate  18  there is arranged a mount for the syringe flange  25  which, in the exemplary embodiment illustrated, is formed by four pins  26 . 
   In addition, the plate  18  has on each side, at the top and bottom, in each case a pin  27 , whose function will be explained later. 
   The syringe  16  has a needle  29 , which can possibly be exchanged via a nut  28 . At the lower free end of the holding arm  4 , a needle guide holder  30  of smaller diameter is provided at the end of a rod  31  which can be pressed upwards counter to spring prestress and, at a distance below this, a needle guide holder  32  of larger diameter on a yoke  33 , which is arranged at the end of two rods  34  that can be pressed upwards against spring prestress. The needle guide holder  32  can accommodate the needle guide holder  30  within itself. 
   The needle guide holders  30 ,  32  are sleeves which are open at the top and closed at the bottom and slotted from the front side beyond the centre and have permanent magnets  35  inserted at the bottom. The needle guide holders  30 ,  32  are used to accommodate a needle guide  36  in each case, which comprises a round sheet metal disc  37  with a central opening  38  for the needle  29  with a pin  39  fixed thereto. 
   The supports  6  in each case comprise a plate  40 , to which in its central region there is fixed a U-shaped bracket  41 , whose lateral limbs each have two vertical holding slots  42  for the pins  27  of the holder  17 , the spacing of the lateral limbs corresponding substantially to the width of the plate  18 . 
   Also arranged on the plate  40  are two holding bushes  43  for the pins  39  of the needle guides  36 , arranged one above the other on the side facing the holding arm  4 . The holding bushes  43  are notched horizontally on the entry side, in order to accommodate a transverse pin  44  on the pin  39 . The transverse pin  44  extends in the plane of the sheet metal disc  37 , so that the latter is aligned horizontally as a result. 
   Furthermore, at the upper end of plate  40  there is provided a projection  45  which has a depression  46  and to which in each case an angled holding plate  47  is fixed at the side. The angled holding plates  47  serve to be pushed into vertical slots  48  in a removable head  49  of the actuator  11 . The piston holder  11  bears an angled piece  50  which closes the vertical slots  48  at the top and opposite which the head  49  can be positioned via a positioning pin  51 . In addition, the head  49  is held on the angled piece  50  by one or more permanent magnets  50   a.    
   In order to transfer a syringe  16 , the holding arm  4  moves, for example, from the position illustrated in  FIG. 5  up to the holder  6 , until the vertical slots  48  are located over the angled portions of the holding plates  47 . In this position, the pins  27  are also located above the holding slots  42 , and the pins  39  of the needle guides  36  are accommodated at the ends by the holding bushes  43 . The holding arm  4  is then lowered, so that the plates  47  come into engagement with the vertical slots  48  and the pins  27  with the holding slots  42 . This also achieves the situation where the needle guides  36  are separated from the needle guide holders  30 ,  32 , counter to the force of the permanent magnets  35 . The holding arm  4  is then moved horizontally away from the support  6 . In this case, the support  6  holds the holder  17  back counter to the force of the permanent magnets  21  via the engagement of the pins  27  with the holding slots  42 , so that the holding arm  4  is separated from the holder  17 . 
   Transferring a holder  17  from the support  6  is carried out in a correspondingly converse way. 
   During sampling or during sample discharge, the holding arm  4  with the holder  17  moves into the appropriate position and is lowered until the needle guide holder  32  is located above the appropriate insertion opening for the needle  29 . It is then lowered further, while guiding the needle  29 , the needle guide holder  30  being accommodated by the needle guide holder  32  and, finally, the entire needle being inserted approximately as far as the nut  28 . A sample is then taken by means of an appropriate suction stroke or a sample taken is injected by means of a pressure stroke, in each case effected by the spindle  12 . During these actions, in which the piston is moved within the syringe  16 , the positioning pins  20  are used to hold the holder  17  and therefore the syringe  16  against vertical displacement. 
   If use is made of a fibre coated for the adsorption of substances to be examined, then this fibre is arranged in the syringe  16 , fixed to its piston, and pushed out appropriately through the needle  29  for the purpose of sampling or sample discharge. 
   Instead of the permanent magnets  21 , a detent which can be released by a pulling force can also be provided for the positioning pins  20  in the plate  8 . This also applies to holding the head  49  by means of the actuator  11 . In addition, the respective holding can also be carried out electromagnetically or by means of a mechanical interlock. 
   Instead of or in addition to the positioning pin  51 , the actuator  11  can have a horizontal guide groove for a corresponding extension on the angular piece  50 . 
   In the embodiment illustrated in  FIG. 9 , the sample handling device is used for handling a sample tube  53  which is located on a gripper  52 , which, for example, accommodates a pin with a coating that adsorbs substances to be examined and which can be inserted into a discharge opening in a gas chromatograph sealed off by seals  54 , the substances to be examined then being desorbed thermally, for example. 
   The gripper  52  has a holding head  55  for one end of the sample tube  53 , with the holding head  55  having in its interior a plurality of balls arranged equidistantly in the circumferential direction, for example three balls which are spring-loaded inwards and which engage in a groove  56  on the valve head of the sample tube  53 , in order to hold the latter. The gripper  52  further has an actuating rod  57  with a piston arranged under spring stress in the holding head  55 , and an actuating head  58 . The actuating rod  57  can be pressed into the holding head  55  against the spring bias, so that the balls in the interior of the holding head  55  come out of engagement with the groove  56 , and the sample tube  53  is released. This can be done in that, if the sample tube  53  is held in a specific position, for example in a sample device of a gas chromatograph or a transfer station or the like, by means of the spindle  12 , the actuator  11  acting on the actuating head  58  is moved appropriately. Instead of the balls, expandable claws or springs can also be provided. 
   The actuating rod  57  is held by a mounting  59  at the upper end of the plate  18  such that it can be displaced longitudinally and therefore pressed into the holding head  55 , and the holding head is held by a mounting  60  at the lower end of the plate  18 . As in the preceding example, the plate  18  can be suspended in a holder  6  and can be removed from the holding arm  4 . 
   In the embodiment illustrated in  FIGS. 10 ,  11 , as compared with the embodiment of  FIG. 3 , the needle guides  37  are not held in the needle guide holders  30 ,  32  by magnets but by stirrup-shaped wire springs  30   a ,  32   a , whose limbs project on two opposite sides through corresponding slots in the needle guide holders  30 ,  32  into the interior of the latter above the respective needle guide  37  and, as a result, hold these firmly. When the holding arm  4  is moved downwards, the limbs of the wire springs  30   a ,  32   a  are expanded and therefore the needle guides  37  are released. 
   In the embodiment illustrated in  FIG. 12 , needle guides  61  and  62  are formed in a pot shape with a passage opening at the bottom for the needle  29  of the syringe  16 , it being possible for the lower needle guide  62  to accommodate the upper needle guide  61 . The needle guide  61  is provided with an extension  63  which, on the underside, bears a permanent magnet  64 , and on its free end, bears a further permanent magnet  65 . The first serves to hold the needle guide  61  on a holding plate  66  which is fixed to the plate  40  and has a corresponding holding recess  67  for the needle guide  61 . Centring is carried out via a pin  68 , which engages in a slot in the holding plate  66 . 
   Under the holding plate  66  there is a further holding plate  69  with a holding recess  70  for the needle guide  62 . The latter has a fork-like extension  71  with a yoke  72 , which bears a permanent magnet  73  at the centre. 
   The rod  31  bears two pins  74  which, for this purpose, extend at right angles in the direction of the needle guide  61  to engage in corresponding holes in the front of the extension  63 , and also a mating piece  75  for the permanent magnet  65 . The yoke  33  likewise bears two pins  76  which, for this purpose, extend at right angles in the direction of the needle guide  62  to engage in corresponding holes in the front of the yoke  72 , and also a mating piece  77  for the permanent magnet  73 . 
   If the pins  74  and  76  are brought into engagement with the extension  63  and the yoke  72 , then by moving the holding arm  4  and therefore the rods  31 ,  34  up, the needle guides  61 ,  62  with the needle  29  can be taken off the holding plates  66 ,  69 , and therefore the syringe  16  can be accepted from the support  6  by the holding arm  4  or transferred to the holder  6  by moving the holding arm  4  down and away. 
   The mating pieces  75 , can also be interchanged with the permanent magnets  65 ,  73 . 
   While the invention has been shown and described with reference to the preferred embodiments, it should be apparent to one ordinary skilled in the art that many changes and modifications may be made without departing from the spirit and scope of the invention.