WO2011110141A1 - Pipetting unit and pipettor comprising such a pipetting unit, and pipette tip for use with such a pipettor - Google Patents

Abstract

The invention relates to a pipette unit with an uptake shaft (3) on which pipette tips (7) of different size can alternatively be arranged via a multitude of uptake surfaces (6.1, 6.2) arranged coaxially about an axis of symmetry (5), with advantageous presence of an equal number of pump chambers (1.1, 1.2) and uptake surfaces (6.1, 6.2) which open into different external orifices (4.1, 4.2) in the uptake shaft (3). Depending on the uptake surfaces (6.1, 6.2) in which they are inserted, the pipette tips (7) can thus be connected to a different number of pump chambers (1.1, 1.2), which allows the pump volume to be optimized to the capacity of the particular inserted pipette tip (7). The invention also relates to a single-channel pipettor and to a multichannel pipettor consisting of at least one inventive pipette unit and to a pipette tip (7) suitable for use with such a single-channel pipettor or such a multichannel pipettor.

Description

 description

 Pipetting unit and pipettor, comprising such a pipette unit, and pipette tip for use with such a pipettor

 The invention relates to a pipetting unit and a pipettor with at least one such pipetting unit. The pipettors are so-called bubble pad pipettes and can be distinguished in single-channel and multi-channel pipettors. They can be operated both manually or as an electric motor. A generic pipetting unit as well as a generic pipettor are known from JP 08117618 A.

 Most known from the prior art pipettors comprise per specified in the name of the pipettor channel each have a pumping chamber and a piston guided therein, wherein the pumping chamber adjacent to a receiving device through which extends a connecting channel, via which the

 Pumping chamber with a mounted on the receiving device pipette tip is in communication. Subsequently, the area enclosed by the connecting channel space, which is bounded by the pipette tip by an outer opening on the receiving device, to be understood as belonging to the pumping chamber.

 The piston can be associated with a pipette belonging to the drive and control device and thus motorized lifted or lowered over a given piston stroke, which, by generating a negative pressure or overpressure within the pumping chamber, taken on the pipette tip liquid or can be delivered. The piston stroke can also be effected manually.

 For aforementioned pipettors, the number of channels indicated in the designation of the pipettor corresponds to both the number of pumping chambers and the number of pipette tips which can be fastened at the same time to the pipettor. As will be shown later, however, there are pipettors in the prior art in which the number of channels does not coincide with the number of pumping chambers, since a plurality of pumping chambers each with a pipette tip or a pumping chamber via a manifold with several pipette tips are in communication ,

 However, the number of channels is always consistent with the number of pipette tips that can be attached at the same time to the pipettor.

In the literature, the distinction of pipettors has prevailed based on a number of channels, although strictly speaking, the pipette tip number is meant. The indication of this number is for information about how many vessels or Wells of a sample plate can be filled simultaneously, which is necessarily determined by the number of pipette tips, but not necessarily by the number of channels.

 In this sense, the following is the use of the terms single-channel and

Multi-channel pipettor be understood.

A single-channel pipettor accordingly comprises a pipetting unit consisting of one

Receiving device, at the same time only a pipette tip can be attached, as well as all connected to the one receiving device pumping chambers with the piston guided therein.

 A multichannel pipettor accordingly consists of a number of pipetting units equal to the stated number of channels.

 Due to the different volumes to be transferred and multiple vessel systems for which pipettors are used today, there are, for example, 1-channel, 4-channel, 8-channel, 96-channel, 384-channel and 1536-channel Pipettors used in conjunction with commercial sample plates or vessel arrangements.

 Commercially available sample plates have this suitable 8x12 (equal to 96), 16x24 (equal to 384) or meanwhile also 32x48 (equal to 1536) wells. Their external dimensions are the same to be compatible with laboratory equipment and handling equipment. As a result, the center distances between the pits become smaller as the number of pits on a sample plate increases. Consequently, the diameter and thus the possible receiving volume of the wells must be reduced.

 As the center distances of the depressions become increasingly smaller, the possible installation space for the pipetting units of a multichannel pipelayer, which must have a center distance equal to the center distances, is reduced in the horizontal direction, so that the axes can be picked up and discharged from the sample plates the pipetting units hit the centers of the wells.

 A pipette tip represents a "usually rotationally symmetrical hollow body, with a discharge opening, via which a liquid can be received and discharged, and a receiving opening, via which the cavity enclosed by the hollow body via the receiving device with the pumping chamber in

 Connection is made.

For pipetting a attached to a pipette pipette tip with the discharge opening is immersed in the liquid to be transferred and by generating a negative pressure in the associated with the pipette tip pumping chamber, a certain volume of liquid is added to the pipette tip (Void volume). The maximum possible intake volume is limited by the maximum piston stroke. In practice, however, only such a volume should be taken up as corresponds to the capacity of the pipette tip in order to avoid contamination of the pipette unit. The pipette tips are usually designed as disposable items, also called disposable items, and are replaced after use.

 For this purpose, the pipette tip is attached via a quick release, non-positive connection to the receiving device.

 The receiving unit of known from the prior art pipetting is often designed so that only pipette tips same Anschlußgeometrie and connection dimensions can be attached to it.

 There are several different principles for attaching a pipette tip to a receptacle.

 According to one principle, a trained around the receiving opening of the pipette tip end face is positively connected to a formed on the receiving device end face. On this mounting option will not be discussed in more detail below, since it is not used in connection with the invention and has been used only for 96er and 384er systems.

 According to another principle, the frictional attachment of the pipette tip can be carried out by sliding onto the receptacle formed as a receiving shaft on which is formed for this purpose a receiving surface in the form of an outer cone or an outer cylinder. With the application of a correspondingly high counterforce by means of an existing Abwerfmechanismus (ejector), the pipette tip can be automatically released from the receiving device.

 The pipette tips are suitable for this purpose in an adjacent to the receiving opening area, hereinafter called pipette collar formed in the form of an equal or slightly smaller dimensioned inner cone or inner cylinder.

 But also the insertion of pipette tips with conical outer diameter in cylindrical holes of holding plates is available in connection with the aforementioned 96 and 384 systems on the market (US 6,622,578).

 Due to the different sizes to be transferred volumes and pipette tips of different sizes, that is used with a different capacity. They differ in their different lengths and inside diameters. Usually, the inner diameter becomes smaller towards the discharge opening. The smaller the inner volume of the pipette tip, the lower the capacity and the more sensitive a liquid volume can be delivered.

By the concrete dimensioning of the receiving surface on the receiving shaft can a pipette unit can be used only with pipette tips, which have a matching pipette collar, with a connection geometry suitable for the receiving surface and matching connection dimensions.

 Although there are pipette tips that have a different capacity for a same sized pipette collar due to different internal volumes, whereby the range of the possible transmission volume (dynamic range) of a pipetting unit can be increased by simple tip change, however, such an increased dynamic range is often not enough to realize all application intentions of the user. In addition, the accuracy of the volume delivery (pipetting accuracy) decreases with smaller dispensing volume, since the size of the pumping chamber for the largest dispensing volume must be sufficiently large and thus oversized for a very small dispensing volume.

 A decision for the very cost-intensive purchase of a particular pipettor makes the user depending on the purpose.

 As a rule, he will not make a decision for a pipettor that is optimized for larger transfer volumes per pipette unit than it intends to pipette per pipetting step, since large-volume pipette tips are provided for this purpose which do not allow accurate dispensing of a smaller volume allow.

 Basically, therefore, he is limited in his decision for a special pipettor on the transmission of volumes within the predetermined volume range, for which the pipetting units are optimized in conjunction with the associated pipette tips.

 If larger or smaller volumes are to be transferred, another pipettor must be used.

 This means that ultimately a user who wants to transfer different volumes for different applications, with only one pipettor alone does not get along.

 Recognizing this problem, two fundamentally different approaches have been taken in the prior art in order to increase the dynamic range of a pipetting unit.

 On the one hand, solutions have been proposed for multichannel pipettors in which a plurality of pipetting units are connected to a pipette tip.

 On the other hand, solutions are known in which pipette tips with a different pipette collar can alternatively be attached to a pipetting unit.

 The former solutions include a multichannel pipettor as disclosed in US Pat. No. 6,841,130 B2.

The free ends of each other in a fixed grid channels are grouped together via an adapter plate so that they are in each case via a pipette tip with the liquid to be absorbed in combination. So can z. For example, a 384 channel multichannel pipettor with an adapter plate connecting 4 channels each with a pipette tip can be adapted for use on a 96-well sample plate. At the same time can be increased by the quadrupling of the effective capacity and the use of a pipette tip with a larger inner diameter and thus increased recording volume, the maximum transfer volume and thus the possible range of the transfer volume, which is also referred to as dynamic range, be significantly increased.

 The above advantages are contrary to the fact that per pipetting, that is, the simultaneous, one-time dispensing a liquid volume, instead of a sample plate with 384 wells only a sample plate with 96 wells can be filled. A multi-channel pipettor, which is actually for a high temporal

 Throughput of 384 fillings per pipetting step is designed, is reduced in its efficiency to a quarter. Another disadvantage is that with the attachment of the adapter plate all channels are summarized in corresponding groups. That is, the Mehrkanalpipettor can either only without adapter plate for filling z. B. 384 wells with smaller volumes or with adapter plate for filling z. B. 96 wells with larger volumes can be used.

 For the purposes of the invention, for example, four combined channels and the related part of the adapter plate, to which a pipette tip can be attached, form a pipetting unit.

 The last-mentioned disadvantage is to be solved with a pipetting attachment according to the European patent application EP 2 006 021 AI.

 The pipetting attachment described here represents an adapter between 4 channels of a multichannel pipettor and a tip (pipette tip). It has on one end face four mutually fixed Aufsteckhülsen (pipette collar), with which the adapter is placed on the free ends of the channels , and at the other end a connection piece for attaching a tip. The axis of the tip passes through the center of the arrangement formed by the four channels.

This solution has the same advantages as the previously appreciated prior art according to US 6,841,130 B2. In addition, the pipetting attachments can theoretically be used as needed, that is, a part of the channels can be grouped together via a pipetting attachment used for pipetting larger transfer volumes, while another part of the channels, as conventionally common, each provided with a pipette tip, used for pipetting smaller volumes. Whether this flexibility is practically used is to be doubted, since the pipette tips then have different center distances to each other, whereby commercially available sample plates, the same Center distance of the wells have each other, are not usable.

 Also in this solution, the four channels combined in the adapter form a pipetting unit according to the invention.

 The second-mentioned solutions include a liquid handling apparatus disclosed in Japanese Patent Laid-Open No. 08117618A.

 This liquid handling device (pipettor) can be used like generic type pipetting units singly or in a plurality in a single-channel or multi-channel pipettor.

 It also works on the principle of air displacing Kolbenhubpipettoren, also called Luftpolsterpipettoren, like all other solutions mentioned in the description of the prior art.

 The peculiarity of the liquid handling device disclosed here is that it has a receiving adapter, in the context of the invention, a receiving shaft having two receiving surfaces for the attachment of pipette tips. The receiving surfaces are designed as outer cones. As can be seen from the summary and the drawings, two cylindrical pumping chambers are formed within the liquid handling device with a different diameter, in each of which a piston is guided. The two outer cones are each coaxially arranged around one of the two pumping chambers, connected to this. The pumping chambers are for a different size. Volume intake designed and optimized for pipette tips of different sizes, in order to be able to pipette alternatively via both pipette tips with high accuracy. The pistons are connected to a common drive and control device so that always both pistons are moved simultaneously.

 [0045] The advantage of a pipettor comprising the liquid handling devices described herein as compared to the previously described prior art solutions is seen in addition to a higher pipetting accuracy in that, whether the liquid handling device for a smaller volume intake with a smaller pipette tip or working with a larger pipette tip for a larger volume intake, can be pipetted into the same sample plates, since the pipette tips are arranged with an equal center distance to each other.

 A disadvantage is seen that the necessary space in the horizontal

Direction in the area of the receiving surfaces for placing the pipette tips comparatively doubled. Even the attachment of pipette tips turns out to be difficult, since each unused Außenkonen can be a hindrance.

 In addition, in automatic processes, an offset from the coordinate system must always be expected for the second channel.

The invention is based on the object, a pipetting with a high Dynamic range for use with different pipette tips to create, which requires only a small horizontal space in the receiving surfaces for attaching the pipette tips, especially to form of a plurality of such pipetting a Mehrkanalpipettor, in which the center distances of infected pipette tips are low to each other.

 Advantageously, by increasing the dynamic range, the pipetting accuracy should not be affected.

 The object of the invention is also to provide a pipettor, namely a Einkanalpipettor or a Mehrkanalpipettor with at least one pipetting unit with a high dynamic range for use with different pipette tips, which in the receiving surfaces of the pipette for attaching the pipette tips only a small horizontal space needed.

 In addition, a pipette tip is to be created, which can be used with a pipettor formed from at least one such pipette and can be dropped by an ejector.

 The first object of the invention is achieved by a pipetting unit for use with various pipette tips having at least one pumping chamber in which a piston is guided, and a receiving shaft having at least one outer opening into which opens the at least one pumping chamber, wherein the receiving shaft at least has two rotationally symmetrical receiving surfaces for sealingly attaching different pipette tips, solved by the receiving surfaces are arranged coaxially to each other and having an outwardly increasing vertical distance to an axis of symmetry.

 Advantageously, a first receiving surface is formed by an inner cylinder formed on the receiving shaft and at least one second receiving surface by an outer cylinder or outer cone formed on the receiving shaft.

 Alternatively, all the receiving surfaces may advantageously be formed by formed on the receiving shaft outer cylinder or outer cones, which are arranged one above the other in the direction of the axis of symmetry, whereby only one type of pipette tips must be used.

 The receiving surfaces, designed as outer cylinder and outer cones have in their arrangement outwardly increasingly larger diameter, which pipette tips larger attachment dimensions can be plugged, which then usually have a larger capacity.

Particularly advantageous for a constant Pipettiergenauigkeit, with increasing dynamic range, the pipetting unit has an equal number of pumping chambers, as receiving surfaces are formed on the receiving shaft and each open into a different opening. Here is a central outer opening present, which lies on the axis of symmetry and between two receiving surfaces is provided in each case an off-center outer opening.

 A pipette tip, which is placed on the innermost, first receiving surface, is therefore associated with only one pumping chamber. A pipette tip placed on the second receiving surface, which is closest to the outside, stands with two

 Pumping chambers in conjunction and so on. In other words, a pipette tip sitting on the xth receiving surface counting from inside to outside is also connected to x pumping chambers. The sum of the pumping chamber volumes of the pumping chambers, which are connected to a pipette tip, can thus be optimized for the capacity of this tip, if the pipette tips are dimensioned so that they have a larger receiving opening and thus larger connection dimensions, which means that they are located further out Recording surfaces are plugged, also have a larger capacity.

 As has already been explained with reference to the prior art, pipette tips of different capacities can be produced with the same connection dimensions. This means that instead of x different pipette tips, which differ in their capacity and their connection dimensions so that each recording surface on the receiving shaft can be assigned by the correlating connection dimensions only pipette tips of a given capacity, all pipette tips could be provided regardless of the capacity with connection dimensions, as they are z. B. to the x-th receiving surface fit. The receiving shaft would then not have to be provided with several different receiving surfaces.

 To then connect the pipette tips depending on their capacity only with selected Pumpkammem, a selection mechanism for selectively operating the individual pistons and individually controllable valves must be provided to the openings through which the pipette tip is in each case a pumping chamber in communication to release or close. It can be connected in this way each with a plugged tip different Pumpenkammem or a different number of Pumpkammem. However, the need for the valves and the control of this and the selection mechanism make the pipetting unit more expensive and prone to failure.

In a erfiridungsgemäßen solution, however, in which the pipette tips of different capacity are put on different receiving surfaces, neither valves nor a selection mechanism are required. Advantageously, all pistons are connected to one another here and are raised and lowered via a mechanism, regardless of whether the respective associated pump chambers are in contact with a pipette tip and thus come into effect or not. whereby her stroke has no effect.

 A further object of the invention is achieved with a single-channel pipettor comprising a pipetting unit according to the invention or with a multichannel pipettor comprising a multiplicity of pipetting units, of which at least one pipetting unit is a pipetting unit according to the invention.

 So z. For example, a multichannel pipettor may comprise eight pipetting units to which only one associated pipette tip may be attached in accordance with the prior art and which accordingly have a relatively small dynamic range while an additional pipetting unit of the present invention will have an increased dynamic range by alternative use with different pipette tips. has high pipetting accuracy.

 Advantageously, a single-channel pipettor according to the invention or a multichannel pipettor according to the invention has an ejector with which a pipette tip which is connected to a receiving shaft can be stripped off from it.

 For a pipette tip with a receiving opening and a discharge opening, for

Use with a single-channel or multi-channel pipettor according to the invention, which is equipped with an ejector, the object of the invention is achieved by an outer cylinder is formed around the receiving opening, which can be inserted into an inner cylinder formed on the receiving shaft, and a projection adjacent to the outer cylinder is provided with a facing the receiving opening plan face on which the ejector can be applied.

 The projection can advantageously be a plate-shaped or cup-shaped

 Cantilever.

 The pipetting unit will be explained in more detail below by way of example with reference to the drawing.

In the drawings:

 [0067] FIG. 1a is a schematic diagram of a pipetting unit provided for an optional

 Inclusion of two different types of pipette tips and a pumping chamber

 1 b, a pipette unit according to FIG. 1 a, to which a pipette tip of the first type is attached in a first embodiment

 1c, a pipette unit according to FIG. 1a, to which a pipette tip of the second type is fastened

 2a shows a schematic diagram of a pipetting unit with two pumping chambers, at the one

Pipette tip of the second type is attached

2a shows an embodiment of a receiving shaft for a pipetting unit intended for the optional accommodation of three pipette tips, to which a pipette tip of the second type is fastened. [0071] FIG Fig. 3b shows another embodiment of a receiving shaft for the optional

 Recording of three pipette tips

4a shows a receiving shaft to which a pipette tip of the second type is attached and a ejector arranged thereon

4b shows a receiving shaft, on which a pipette tip of the first type in a second

Execution is fixed and a thereto arranged ejector

FIG. 4c shows a receiving shaft on which a first type of pipette tip in a third

Execution is fixed and a thereto arranged ejector

5a shows a schematic diagram for a single-channel pipettor

FIG. 5b shows a schematic diagram for a multichannel pipettor. FIG

 1a-1c show a first exemplary embodiment of a pipetting unit according to the invention and different pipette tips 7 attached to it.

 Different pipette tips 7 are to be understood here as having a different connection geometry and / or different connection dimensions for attaching the pipette tip 7 to a receiving shaft 3.

 The pipette tips 7 that can be used with a pipetting unit according to the invention are subsequently distinguished on the basis of their different connection geometry in pipette tips of the first type 7.1 and pipette tips of the second type 7.2.

 The pipette tips of the first type 7.1 and the second type 7.2 may have different connection dimensions and other different dimensions, such as different inner diameter and different lengths, depending on which areas of delivery volumes they are optimized. The ratio of the adding volumes of the pumping chamber 1 and the pipette tip 7 used to the piston stroke determines the smallest deliverable volume of liquid and its accuracy. The highest pipetting accuracy is theoretically achieved when the volume of the pumping chamber 1 (at the maximum extended piston 2) is equal to the capacity of the pipette tip 7.

 On a pipette tip of the first type 7.1 is around the receiving opening 11, that is, at the end to which the pipette tip 7.1 is attached to the receiving shaft 3, designed as a joining surface outer surface, in particular a cylindrical / conical outer surface, with the pipette tip 7.1 can be inserted into a formed on the receiving shaft 3 inner cylinder / inner cone.

 In the case of a pipette tip of the second type 7.2, an inner surface configured as a joining surface is present around the receiving opening 11, in particular a conical or cylindrical inner surface with which the pipette tip 7.2 can be slipped onto an outer cone or outer cylinder formed on the receiving shaft 3.

The area of the joining surfaces at the pipette tips 7 will be referred to below as pipette collars. So it's exactly this pipette collar that's one of the ordered receiving surface 6 matching connection geometry and matching connection dimensions.

 From purely geometrical considerations it follows that pipette tips of the first type 7.1 can accommodate significantly smaller volumes than those of the second type 7.2.

 A pipetting unit, as shown in FIG. 1 a, comprises as essential to the invention

 Features a pumping chamber 1, a piston 2 and a receiving shaft. 3

 The pumping chamber 1 is formed by a cylindrical chamber in which the piston 2 can be raised and lowered in a sealed manner towards the chamber wall, and a connecting channel between the chamber and a central outer opening 4.1 formed on the receiving shaft 3.

 Comparable with receiving shops, as they are known from generic same pipetting units from the prior art, the receiving shaft 3 has an outer receiving surface 6.2 for it aufsteckbare pipette tips second type 7.2, which is designed as an outer cone. This outer receiving surface 6.2 includes a small cone angle a with the axis of symmetry 5 of the receiving shaft 3, which can be up to zero in the extreme case, whereby the outer cone merges into an outer cylinder.

 On such an outer receiving surface 6.2 pipette tips of the second type 7.2, as shown in Fig. Lc and as they are commercially available, by

 Force in the direction of the axis of symmetry 5 are postponed. For this purpose, the pipetting unit is usually placed on a pipette tip of the second type 7.2, which hangs vertically in a storage box, wherein the receiving shaft 3 is inserted into the receiving opening 11 of the pipette tip of the second type 7.2.

 In this case, the pipette tip of the second type is slightly stretched 7.2 in the radial direction and stored a restoring force in the material of the pipette tip of the second type 7.2, which ensures a seal against the outer receiving surface 6.2. In addition, a sealing rubber (O-ring on the shaft) can be provided for sealing. The pipette tip axis and the symmetry axis 5 of the receiving shaft 3 coincide after the pipette tip has been mounted.

 What is new in comparison with the prior art is that the receiving shaft 3 has further coaxial receiving surfaces 6, which are numbered consecutively beginning from the achsnesten receiving surface 6.1 for further explanations. The outer receiving surface 6.2 just described, as is customary in the prior art, is therefore referred to as a second receiving surface 6.2.

According to the first embodiment, the receiving shaft 3 has two receiving surfaces 6. The first and thus achsnste receiving surface 6.1 is formed by an end portion of the connecting channel, which extends through the receiving shaft 3 and ends in the central outer opening 4.1. The tail represents a cylinder with a sufficiently large diameter to plug a pipette tip first type 7.1 can. An insertion takes place as already described plugging with the difference that a pipette tip of the first type 7.1 is radially compressed slightly when inserted.

 A pipetting unit according to the first embodiment enables an alternative operation of the pipetting unit with pipette tips 7, which are provided for two different ranges of delivery volumes.

 Particularly advantageous from such pipetting, by arranging several of these pipetting with a center distance equal to or a multiple of the center distance of wells commercial sample plates, multi-channel pipettors form.

 Since the receiving surfaces 6 are mutually coaxial about the axis of symmetry 5 of the receiving shaft 3, the relative arrangement of a single-channel pipettor or a MehrkanalpipettOTS to a sample plate, in which pipetting is maintained even after changing the size of the pipette tips 7.

 This means, in particular, that in connection with automated pipettors

 used handling systems such as transport devices, lifter or gripper can be used unchanged and with the same control, regardless of which of the pipette tips 7 is used.

 According to the first exemplary embodiment, the two attachable pipette tips 7.1, 7.2 are alternatively in each case connected to the same pumping chamber 1. Alternatively, both pipette tips 7.1, 7.2, which have a different capacity to be able to fill a maximum for efficient operation, the possible displacement volume of the pumping chamber 1 must be designed for the receiving volume of the larger pipette tip, whereby the accuracy of the liquid delivery via the smaller pipette tip 7.1 affected becomes.

 According to a second embodiment according to FIGS. 2 a and 2 b, a pipetting unit has two pumping chambers 1.

 The first pumping chamber 1.1 opens like the first embodiment in the central outer opening 4.1 of the receiving shaft 3 and is thus in communication with each pipette tip 7, which is attached to the receiving shaft 3.

 The displacement volume of the first pumping chamber 1.1 is optimized to the capacity of the innermost first pipette tip 7.

A second pumping chamber 1.2 opens into an off-center outer opening 4.2, which is present between the first and the second receiving surface 6.1, 6.2 in the receiving shaft 3, and is thus not in connection with an infected at the first receiving surface 6.1 pipette tip first type 7.1 but only with a pipette tip of the second type 7.2, which is attached to the second receiving surface 6.2. These Pipette tip of the second type 7.2 is thus in communication with both pumping chambers 1.1, 1.2. Advantageously, the displacement volume of the first and second pumping chambers 1.1, 1.2 is optimized to the capacity of the pipette tip of the second type 7.2.

 The principle of operation of a pipetting unit according to the invention makes it possible to realize further outer receiving surfaces 6 on the receiving shaft 3, over which further, even larger pipette tips of the second type 7.2 can be placed.

 Fig. 3a shows a Aufhahmeschaft 3 provided for three pipette tips 7 of different sizes.

 In each case, a first pipette tip 7 is a pipette tip of the first type 7.1 and is inserted into the receiving shaft 3, while each additional pipette tip 7 is a pipette tip of the second type 7.2. The illustrated here, on the third receiving surface 6.3 plugged pipette tip 7.2 communicates with three pumping chambers 1, which by the symbols PI, P2 and P3, standing for the pressure in each one

 Pumping chamber 1, is shown.

 The pipetting unit can be used as part of a pipettor.

 5a shows a schematic diagram of a manually operable single-channel pipettor with the pipetting unit, comprising a pumping chamber 1 and a receiving shaft 3 and an ejector 9, which can be lowered counter to a spring force F in the direction of the axis of symmetry 5 'to one on the receiving shaft. 3 stripped pipette tip 7 (not shown here) strip.

 Fig. 5b shows a schematic diagram of a multi-channel pipettor.

 The pumping chambers 1 are fixedly connected to one another to form a rigid arrangement of the pipetting units. The guided in the pumping chambers 1, not shown piston 2, are moved, for example via a common actuator. The ejector 9 is formed in the area around the pumping chambers 1 as a plane plate, which strips all lowering seated on the receiving shafts 3 pipette tips 7 (not shown here) when lowering.

 In the case of motorized pipettors are also drive and

Control units and a power supply or interfaces for connecting a power supply available.

 FIG. 3b shows a receiving shaft 3 provided for three pipette tips 7 of different sizes, all of which are pipette tips of the second type 7.2. The receiving surfaces 6 are offset in the direction of the axis of symmetry 5 to each other, so that the receiving shaft 3 receives a stepped outer contour.

Commercially available pipette tips are used as pipette tips of the second type 7.2. They have at their receiving opening 11 on an outer collar with a flat end face 8 extending radially to the tip axis. As shown in Fig. 4a, an ejector 9, the z. B. by a lowerable, the receiving shaft 3 enclosing plan plate is formed, are applied to the front side of the outer collar, so that in a further lowering of the ejector 9, the pipette tip 7.2 is stripped from the receiving surface 6.2. Such ejectors 9 are known from the prior art. So that the ejector 9 z. B. in one embodiment of a receiving shaft 3 of FIG. 3b for all pipette tips 7.2 is effective, regardless of which of the three receiving surfaces 6, the pipette tip sits 7.2, the outer collars of the smaller pipette tips must be 7.2 only made thick accordingly, so they have the largest outer diameter 'of the intake 3.

 Such an ejector 9 does not function in connection with pipette tips of the first type 7.1, if they are formed as shown in Fig. 2b.

 According to the invention, a projection 10 may be formed on a pipette tip of the first type 7.1, which is designed so that an ejector 9, as shown in Fig. 4a, a pipette tip of the second type 7.2 can strip off when lowering with this projection 10 comes in contact and in a further lowering this entrains and thus strikes. The projection 10 adjoins the outer periphery of the pipette tip 7 at a distance greater than the length of the joining surface to the receiving opening 11.

 As shown in FIG. 4b, it may be plate-shaped or cup-shaped as shown in FIG. 4c. The pot-shaped projection 10.2 has the advantage that the ejector 9 for stripping a pipette tip of the first type 7.1 thus formed only has to be lowered by the same distance as for dropping a pipette tip of the second type 7.2.

 0117] Used reference numerals

 0118] 1 pumping chamber

 0119] 1.1 first pumping chamber

 0120] 1.2 second pumping chamber

 0121] 2 pistons

 0122] 3 pick-up shaft

 0123] 4 outer opening of the receiving shaft

 0124] 4.1 central outer opening

 0125] 4.2 eccentric outer opening

 0126] 5 symmetry axis of the receiving shaft

 0127] 6 pickup area

 0128] 6.1 first receiving surface

 0129] 6.2 second recording area

 0130] 6.3 third recording surface

0131] 7 pipette tip 7.1 pipette tip of the first kind

 7.2 pipette tip of the second kind

 [0134] 8 face

 [0135] 9 ejector

 [0136] 10 cantilever

 [0137] 10.1 plate-shaped projection

 [0138] 10.2 cup-shaped protrusion

 [0139] 11 receiving opening of a pipette tip

[0140] 12 Delivery opening of a pipette tip

[0141] α cone angle

 [0142] F force

 [0143] P pressure

Claims

claims  1. pipetting unit for use with different pipette tips (7) with at least one pumping chamber (1) in which a piston (2) is guided, and a receiving shaft (3) with at least one outer opening into which the at least one pumping chamber (1) wherein the receiving shaft (3) has at least two rotationally symmetrical receiving surfaces (6) for the sealing attachment of different pipette tips (7), characterized the receiving surfaces (6) are arranged coaxially with one another and have an outwardly increasing vertical distance to an axis of symmetry (5).  2. pipetting unit according to claim 1, characterized in that a first receiving surface (6.1) formed by a on the receiving shaft (3) inner cylinder and at least a second Receiving surface (6.2) by a on the receiving shaft (3) formed outer cylinder or outer cone is formed.  3. Pipette unit according to claim 1, characterized in that all receiving surfaces (6) formed by the receiving shaft (3) outer cylinder or outer cones are formed, which are arranged one above the other in the direction of the axis of symmetry (5).  4. pipetting unit according to one of claims 1 to 3, characterized in that the pipetting unit has an equal number of pumping chambers (1), like receiving surfaces (6) are formed on the receiving shaft (3), and these in each case open into another opening (4), wherein a central outer opening (4.1) is present and between two Receiving surfaces (6) each have an eccentric outer opening (4.2) is provided.  5. A single-channel pipettor comprising a pipetting unit according to one of claims 1 to 4.  6. Einkanalpipettor according to claim 5, characterized in that it comprises an ejector (9), with which a to the Receiving shank (3) of the pipette unit infected pipette tip (7) can be stripped from this. 7. multichannel pipettor comprising a plurality of pipetting units, of which at least one pipetting unit is designed according to one of claims 1 to 5. 8. Mehrkanalpipettor according to claim 7, characterized in that it comprises an ejector (9), with which the to the Receiving shops (3) of the pipetting units infected Pipette tips (7) can be stripped from these.  9. pipette tip with a receiving opening (11) and a A dispensing port (12) for use with a single channel pipettor or multi-channel pipettor as claimed in claim 6 or 8, with an outer cylinder formed around the receiving opening (11) for inserting the pipette tip (7) into the inner cylinder formed on the receiving shaft (3) and a projection (10) adjoining the outer cylinder with a planar end face (8) facing the receiving opening (11) at which the ejector (9) can be applied.  10. pipette tip according to claim 8 or 9, characterized in that the projection (10) is a plate-shaped projection (10.1). 11. pipette tip according to claim 8 or 9, characterized in that the projection (10) is a cup-shaped projection (10.2).