Pipette head, pipetting device with pipette head, and pipetting method using the pipette head

Abstract

A pipetting head for a pipetting device, the pipetting head comprising at least one pipette tip, A holder; at least one attachment held in a holder for clamping to a pipette tip; two elastomeric O-rings held in the attachment; The two O-rings, attachment, and pipette tip are designed to tightly clamp the pipette tip to the attachment through deformation of the two O-rings, which occurs only when the pipette tip is pressed against the two O-rings.

Description

[Technical field]

[0001] The present invention relates to a pipette head for extracting pipette tips, a pipetting device comprising the pipette head, and a method for pipetting liquids using the pipette head.

[0002] Pipetting devices equipped with a pipette head for dispensing a single pipette tip or for dispensing several pipette tips simultaneously are used, inter alia, for metering liquids in clinical, biological, biochemical and chemical laboratories.

[0003] The pipette head has at least one attachment at the upper end of the pipette tip that can be inserted into a mounting opening, and liquid is aspirated into the pipette tip and expelled from there through a tip opening at the lower end of the pipette tip.

[0004] After use, the pipette tip can be removed from the attachment and replaced with a new pipette tip. In this way, contamination of subsequent measurements is prevented. Disposable pipette tips made of plastic are economically available.

[0005] When designed as an air-cushion pipetting device, at least one air displacement device is integrated into the pipetting device and is connected via a connection hole of the respective attachment and communicates with the pipette tip fastened thereon. By means of the displacement device, the air cushion is made movable so that liquid is aspirated into the pipette tip and expelled from it. The displacement device is generally a cylinder with a plunger movable therein. However, displacement devices with a displacement chamber and at least one variable wall are also known, the deformation of which displaces the air cushion.

[0006] In this embodiment as a direct displacement pipetting device, a small plunger is disposed on the pipette tip, and when the pipette tip is attached to the attachment, the pipette tip is coupled to the plunger drive of the pipetting device.

[0007] Preferably, the liquid is aspirated in a single step or in several small steps. When pipetting, the liquid is expelled in a single step, and when dispensing, the liquid is expelled in several small steps.

[0008] Pipetting devices can be driven manually or by electric motors and can be designed as actual multichannel pipettes that are held in the user's hands during pipetting ("hand-held pipettes").

[0009] In a metering station ("pipette station") or metering machine ("pipette machine"), the pipette head is movable by a robotic arm or another transport system, which moves the pipette head above a work surface. The metering station or machine can retrieve a new pipette tip from a holder by the pipette head, draw liquid from a container, expel liquid by the pipette tip into a container, and discard the used pipette tip in a waste container. The pipette head can also be a component of a laboratory machine (workstation) that can perform other processes on the liquid than metering. This includes, among others, mixing, temperature control and control of other physical processes, chemical or biochemical conversions, and sample analysis.

[0010] Attachments for holding pipette tips are often designed as conical, cylindrical or partially conical or partially cylindrical protrusions on the housing of the pipetting device or on another holder. The pipette tips can be fastened to the attachments at their upper end close to the attachment opening by means of a sealing seat. For this purpose, at least one attachment is pressed into the attachment opening of at least one pipette tip available in the holder, so that the pipette tip expands somewhat and rests firmly on the attachment under pretension. The clamping force increases with the number of pipette tips.

[0011] To remove the clamped pipette tips from the attachment, the pipetting device has an ejection device with a drive and an ejector. By activating the drive, the ejector moves, which then removes the pipette tips from the attachment. The drive is either manually driven or driven by an electric motor. The ejection force to remove the clamped pipette tips from the attachment increases with the number of pipette tips.

[0012] A strong force must be applied to clamp the pipette tip into the 8, 12, 16, 24, 96, or 384 attachment and to eject the pipette tip from the attachment.

[0013] German Patent No. 102004003433B4 describes a multichannel pipette, in which the force required to clamp the pipette tip to an attachment and to remove the pipette tip from the attachment is reduced because the attachment is spring-loaded and projects axially beyond a stop formed by an ejector. If the clamping force exceeds a certain value when clamping to the pipette tip, the attachment bends until the pipette tip rests on the ejector. This limits the clamping force to a value at which the pipette tip is held sealingly in the attachment. The ejection force is also limited accordingly.

[0014] EP 2735369A1 describes a multichannel pipette in which an ejector acts as a stop element when the pipette tip slides through the attachment. The ejection force is further reduced if the ejector has multiple contact elements which contact in sequence to press the pipette tip out of the attachment.

[0015] International Patent Publication No. WO 01 / 56695 A1 describes a pipette head with 96 channels, in which the attachment has a larger cone angle at the bottom than at the top in order to reduce the force for attaching the pipette tips with the collar, and the pipette tips have a larger wall thickness at the top and a smaller wall thickness below the collar. The pipette head comprises a stop plate for ejecting the pipette tips from the attachment. The stop plate is stepped in order to push the pipette tips out of the attachment in a sequential manner and reduce the ejection force. A post with a pretensioning device protrudes from the stop plate. The pretensioning device is contacted by a plunger plate which, when contracted, moves a plunger in a cylinder connected to the attachment in order to start ejecting the pipette tips from the attachment by the stop plate. The design with a pretensioning device for ejecting the pipette tips is complex.

[0016] International Patent Publication No. WO2005 / 113149A1 and German Utility Model No. 202005006970U1 describe a device for aspirating and dispensing liquids, comprising a pipette head with 96 attachments for pipette tips. 96 plunger / cylinder units are connected to the attachments and can be manually actuated using a drive mechanism. To remove the pipette tips from the pipette tip holder and to aspirate and dispense liquids, the pipette head can be moved along a vertical guide. To apply the force required to pick up the 96 pipette tips, the pipette head can be pressed downwards with greater force using a transmission lever. To remove the pipette tips from the attachments, the attachments are guided through holes in a vertically movable perforated plate.

[0017] German utility model 202008013533U1 describes a pipetting device with a base plate and an elastic seal plate which laterally covers the base plate on the outside, through which a number of pipette channels arranged in a defined pattern extend. A magazine with pipette tips of the same pattern, each with a collar, is located in a magazine holder, which directly connects the base plate to it by a press fit via the collar and the seal plate. The magazine holder is formed by a magazine frame which is raised and lowered by a drive motor via an eccentric gear in order to bring the pipette tips into sealing contact with the seal plate or to remove the pipette tips from the seal plate.

[0018] Pipette machines that receive pipette tips in a magazine in a magazine holder and press the pipette tips against a seal plate are sold by Apricot Designs, Inc., Covina, California, USA, under the product names "i-Pipette" and "i-PipettePro."

[0019] The disadvantage is that such pipetting machines only work with certain pipette tips in certain magazines, and a further disadvantage is that the magazine holders are filled manually.

[0020] EP 0337726 A2 describes an apparatus for simultaneously removing multiple pipette tips using parallel attachments in series, each of which has an elastomeric O-ring in an annular groove of adjustable groove width. The circumferential stretch of the O-ring can be varied by adjusting the groove width to tightly and sealingly lock the pipette tips to the attachment and to remove the pipette tips from the attachment. To adjust the groove width, each groove is bordered by a threaded sleeve that is screwed to the attachment, and the threaded sleeve can be actuated by means of an associated drive mechanism. Each threaded sleeve is rigidly connected to a toothed wheel. The toothed wheel meshes with a single rack that is driven by a rotatable handle. In an alternative embodiment, each separate threaded sleeve is individually driven by an electric motor, which is connected to a common power source for synchronous operation. The design of the drive mechanism for tightly locking the pipette tips to the attachment is complex.

[0021] DE 19917375 C2 describes a pipette unit comprising a pipette tip and an attachment. The attachment comprises a pipette tube with a coupling sleeve at its lower end, an O-ring made of elastically deformable material which slides on the pipette tube and the sleeve which slides on the pipette tube. The sleeve serves to compress the O-ring axially so that it deforms radially and engages sealingly in an annular groove on the inner periphery of the pipette tip. The pipette tip can be removed by releasing the O-ring. To hold the pipette tip in place on the attachment, the attachment and the pipette tip have interacting axial alignment means. The joining axial alignment means are pretensioned as the O-ring engages in an annular groove on the pipette tip. To eject the pipette tip, a movable ejector is provided which is formed as an ejector tube which surrounds the sleeve. The ejector can be actuated hydraulically or by an electric motor or by a preloaded spring that is tensioned during mounting of the pipette tip to the pipetting unit. The actuation means for rigidly locking and releasing the pipette tip to the attachment are complex and require a large amount of space. Manufacturing tolerances or inaccurate alignment of the pipette tip to the attachment make it difficult to fix the pipette tip in a defined coupling position. The annular groove and the axial alignment means limit the use of a wide variety of pipette tips.

[0022] International Patent Publication No. WO 2018 / 002254 A1 and German Patent Publication No. DE 102016111912 A1 describe a metering head for a metering device with a holder in which a number of parallel attachments for receiving pipette tips are arranged adjacent to one another, each attachment having a tube with an at least partial peripheral support projection at its lower end projecting outwardly from its outer periphery, at least one sleeve surrounding the tube and axially movable thereon, and at least one elastomeric O-ring surrounding the tube and arranged near the lower end of the sleeve. A pressure plate is disposed over the sleeves, the pressure plate having a first plurality of holes through which the tubes extend, the pressure plate being movable along the tubes between a release position at a first distance from the support protrusions and a locking position at a second distance from the support protrusions that is less than the first distance, the pressure plate pressing against upper edges of adjacent sleeves of all attachments in the locking position such that the sleeves are pressed against adjacent O-rings at their lower ends, and the O-rings expand to tightly lock the pipette tips sliding on the attachments. A first displacement device is connected to the pressure plate and is designed to move the pressure plate between the release position and the locking position.

[0023] Fastening and unlocking of multiple pipette tips simultaneously is possible by pressing a pressure plate against all sleeves simultaneously and unlocking all sleeves simultaneously. Transferring force from the first adjustment device through the pressure plate to the sleeves facilitates a relatively simple, compact and lightweight construction. Fastening by expanding O-rings facilitates the use of pipette tips of different shapes and sizes.

[0024] DE 102006036764 describes a pipetting system with a pipetting device, which has at least one mounting shaft with a peripheral locking bead on its outer periphery and two peripheral annular grooves spaced apart below, each for receiving a sealing ring. The pipetting system comprises a pipette tip. The pipette tip can be fastened to the locking bead by means of the locking grooves and has a sealing area below against which the sealing ring abuts in a sealing manner. Such locking allows the pipette tip to be placed as desired on the mounting shaft and the sealing ring to seal the pipette tip to the mounting shaft. A relatively large locking force is required to lock the locking bead into the locking grooves.

[0025] Therefore, an object of the present invention is to provide a pipette head comprising at least one attachment and at least one pipette tip, for reliably ejecting and removing a pipette tip from an attachment with less force and with a simpler design.

[0026] This object is achieved by a pipette head comprising at least one pipette tip having the features of claim 1. Advantageous embodiments of the invention are specified in the dependent claims.

[0027] A pipetting head with at least one pipette tip for a pipetting device according to the invention comprises: A holder; at least one attachment held by a holder for clamping to a pipette tip; two elastomeric O-rings held in the attachment; At the point of contact with the O-rings (24, 25), the inner diameter of the sealing seat (68) of the pipette tip (6) is smaller than the outer diameter of the corresponding O-ring (24, 25), so that the O-rings slide and deform, firmly clamping the pipette tip (68) on the attachment (5); · The O-rings (24, 25) are configured to deform while sliding so that the sealing sheet (68) abuts against the attachment (5) without directly contacting the attachment (5) or applying a force to the pipette tip (6) that would deform the pipette tip. .

[0028] A pipette tip is a long tube with a tip opening at the bottom and a sealing seat at the top near the attachment opening. The sealing seat allows the pipette tip to be locked into an attachment. The inner and outer diameters of the pipette tip typically expand from the tip opening to the attachment opening. When a pipette tip is removed by attachment to a pipette head that has no O-ring, only one O-ring, or one locking bead and two O-rings, a large removal force (locking force) is generated because the pipette tip, made of polypropylene, polyethylene, or another hard elastic plastic, comes into direct contact with the attachment as it slides over and is deformed by the attachment. In the pipette head according to the invention, the two O-rings, the attachment and the pipette tip are designed to firmly clamp the pipette tip to the attachment by deformation of the two O-rings only by pressing the pipette tip against the two O-rings, thus avoiding direct contact of the pipette tip with the attachment and thus avoiding expansion of the pipette tip. In this case, the pipette tip does not directly contact the attachment or only abuts against the attachment without being subjected to forces acting between the attachment and the pipette tip that deform the pipette tip. As a result, when the pipette tip is taken out by the pipette head, only the two O-rings are deformed. In this way, the pipette tip is not directly clamped to the attachment by expanding, but is clamped by means of the two O-rings. The two O-rings are held by the attachment and abut against the pipette tip under pretension by deformation of the O-rings. The O-rings are made of elastomer and therefore can be deformed more easily than the pipette tip. As a result, the pick-up force required to eject the pipette tip is reduced. For handheld pipettes, reducing the clamping force can reduce user strain during manual pipetting.In the case of a pipetting station, a pipetting machine or a laboratory machine, this reduces the requirements placed on the transport system, in particular its strength and the performance of the drive.

[0029] Furthermore, two O-rings ensure that the pipette tip is precisely aligned with the attachment. This is advantageous for introducing the pipette tip into the vessel opening without colliding with the vessel. As a result, especially in the case of hand-held pipetting, the pipette tip is prevented from tilting when its lower end touches the vessel wall. This is recommended by the pipette manufacturer and ensures that the liquid flows out of the tip opening under uniform conditions.

[0030] An added advantage of the two O-rings on each attachment is that all tips can be slid onto the attachment and then pushed further up on the attachment to the subsequent pipetting position. Alternatively, all tips can be pushed up onto the attachment to an ejector or stop so that the clamped pipette tips are always at the same height.

[0031] According to one embodiment of the present invention, the inner diameter of the sealing seat of the pipette tip at the point of contact with the O-ring is smaller than the outer diameter of the corresponding O-ring, so that this O-ring deforms while sliding and clamps the pipette tip firmly on the attachment. According to another embodiment, the inner dimensions of the sealing seat of the pipette tip are determined in such a way that, when the pipette tip is clamped firmly on the attachment by the deformation of the two O-rings, the sealing seat abuts on the attachment without coming into direct contact with the attachment or without exerting a force on the pipette tip that would deform the pipette tip. A preferred embodiment combines the features of the two above-mentioned embodiments regarding the inner diameter and the inner dimensions of the sealing seat. According to a preferred embodiment, this combination replaces the feature in the last bullet of claim 1.

[0032] According to another embodiment, the sealing seat has a cylindrical or conical shape expanding towards the mounting opening. According to another embodiment, when the pipette tip is rigidly fastened to the attachment by deformation of two O-rings, the inner diameter of the sealing seat is greater than or equal to the outer diameter of the attachment in the same cross section as the sealing seat.

[0033] According to a preferred embodiment, the pipette head can be used to aspirate and dispense liquids with at least one clamped pipette tip, since the pipette tip can be hermetically and tightly clamped to the attachment. For this purpose, the pipette head has at least one displacement device, which is connected to a connection hole at the end of the attachment via at least one line in order to move an air cushion and aspirate liquid through the tip opening into the clamped pipette tip and dispense it from the tip opening. The radial deformation of the two O-rings allows pipette tips of different dimensions to be taken up on the same attachment, allowing pipetting operations with pipette tips of different sizes. As a result, the complexity of performing different pipetting operations can be reduced. For example, it is possible to design the O-rings and the attachment in such a way that pipette tips with a nominal volume of 10 μl and 50 μl, or with a nominal volume of 300 μl and 1,000 μl, can be hermetically clamped on the same attachment. For this purpose, commercially available pipette tips from different manufacturers can be used. 1 because they have dimensions that fit into the enclosed area.

[0034] If the dimensions of the various pipette tips vary greatly, the pipette head can be used to transfer pipette tips of different sizes, for example from one pipette tip holder to another, if necessary, since the pipette tips can be firmly placed on the attachment so that they can be transferred with the pipette head, even if they are not hermetically and firmly fastened to the attachment. This can be used in particular for automatically transferring pipette tips in laboratory machines. For example, it is possible to design the O-rings and the attachments in such a way that commercially available pipette tips with nominal volumes of 10 μl, 50 μl, 300 μl and 1,000 μl can be taken and transferred with the same attachment. The invention comprises a pipette head that can be used to transfer pipette tips but not to aspirate and dispense liquids. Such a pipette head for transferring pipette tips can be designed without a displacement device and is hereinafter also referred to as a transfer head.

[0035] According to another embodiment, the O-ring is made of a soft elastomer. According to another embodiment, the O-ring is made of rubber, silicone rubber, fluororubber (FEPM, e.g. Viton® from DuPont Performance Elastomers), hydrated nitrile rubber (HNBR), ethylene propylene diene monomer rubber (EPDM) or a thermoplastic elastomer. O-rings made of soft elastomers (silicone rubber) are in particular sold under the name VMQ by C. Otto Gerckens GmbH (Seal Technology), Pinneberg, Germany.

[0036] According to another embodiment, the attachment has an axial position fixing device, which is designed to support each of the two O-rings at a specific upper position and a specific lower position and to allow the two O-rings to deform in a radial direction, so that the two O-rings can be held at specific positions and areas of the attachment, which can be adjusted to suit the pipette tips to be fitted to the attachment.

[0037] According to another embodiment, the axial position fixing device is an annular groove. Each annular groove can partially accommodate at least one O-ring, which is guided in the bottom of the annular groove of the attachment and cannot move up or down by the two side surfaces of the annular groove. The annular grooves can be dimensioned to hold each O-ring snugly, or with axial play, or with some axial compression in the respective annular groove. Furthermore, it is possible to hold both O-rings in the same annular groove. In this case, both O-rings support each other in the same annular groove, with the upper O-ring supporting against the top of the side surface and the lower O-ring supporting against the bottom of the side surface of the annular groove.

[0038] According to another embodiment, the axial fixing device is formed by one or several projections arranged on the periphery of the attachment on both sides of the at least one O-ring, the axial movement being prevented or limited by at least one projection on both sides of the at least one O-ring.

[0039] According to a preferred embodiment, each attachment has only two O-rings. According to another embodiment, each attachment has more than two O-rings. For each O-ring there may be a separate annular groove or a separate axial fixing device, or several O-rings may be placed together in the same annular groove or held in the attachment by the same axial fixing device.

[0040] According to another embodiment, the axial fixing device is designed integrally with the attachment. According to another embodiment, the axial fixing device is a sleeve and / or a ring which slides on the attachment and which receives an O-ring between them, the O-ring being guided inside the attachment. The sleeve and / or ring is fixed or loosely guided in the attachment and is prevented from sliding off the attachment by further axial fixing means. These may for example be formed by an upper retainer and a lower fixing ring, which is held in a further annular groove on the periphery of the attachment.

[0041] According to another embodiment, the two O-rings are arranged at a distance from each other on the attachment, which is particularly advantageous for a precise alignment of the pipette tip on the attachment, and furthermore, in this way a particularly gentle increase in the clamping force when clamping the pipette tip can be achieved.

[0042] According to another embodiment, the attachment has at least one cone, which is advantageous for clamping the pipette tip to the attachment with a gradually increasing clamping force.

[0043] According to another embodiment, the attachment comprises at least one cylindrical portion, which allows for improved guidance and sealing of the pipette tip into the attachment.

[0044] According to another embodiment, the attachment has an upper cylindrical section at the top, a lower cylindrical section at the bottom, a conical section tapered from the top to the bottom therebetween, an upper axial position fixing device between the upper cylindrical section and the conical section, and a lower axial position fixing device between the conical section and the lower cylindrical section, so that the clamping force when clamping the pipette tip to the attachment can be gradually increased, and the pipette tip can be well guided and aligned to the attachment.

[0045] According to another embodiment, the upper O-ring has a larger inner diameter and / or a larger cross-sectional diameter than the lower O-ring, which is advantageous for gradually increasing the clamping force when clamping the pipette tip to the attachment.

[0046] According to another embodiment, the cross-sectional diameter of the upper O-ring is larger than the depth of the upper annular groove and / or the width of the upper annular groove is equal to or larger than the cross-sectional diameter of the upper O-ring and / or the cross-sectional diameter of the lower O-ring is larger than the height of the lower annular groove and / or the width of the lower annular groove is equal to or larger than the cross-sectional diameter of the lower O-ring. The depth of the respective annular groove allows the respective O-ring to be radially deformed by clamping the pipette tip to the attachment and / or the width of the respective annular groove allows a long deformation path with a small clamping force.

[0047] According to another embodiment, the pipette head has attachments arranged parallel adjacent to one another in one or more rows, so that the pipette head can be used to clamp a large number of pipette tips simultaneously, for which the pipette head is particularly suitable due to its low clamping force.

[0048] According to another embodiment, the attachment is rigidly connected to the holder. Since the two O-rings can keep the clamping forces low, it is not necessary to support the attachment on the holder via a spring, especially for this purpose. According to another embodiment of the pipette head according to the invention, the attachment is supported on the holder via a spring, so as to further limit the resulting mounting forces.

[0049] According to another embodiment, the holder is the housing or part of the housing or the chassis or part of the chassis of the pipette head. For example, the holder is a lower housing wall of the housing of the pipette head or the bottom of the chassis. The attachments can in particular be held by screwing to the lower housing wall or the bottom of the chassis. If the attachments are held at the bottom of the chassis, the housing may have through-holes for the respective attachments in the lower housing wall or may completely dispense with the lower housing wall.

[0050] The invention further relates to a pipetting or transport device comprising a pipette head according to one of claims 1 to 11 or one of the preceding embodiments, which can in particular be designed as a practical pipetting or transport device driven manually or by an electric motor and having one or several channels, which device can be held in the hand of a user during pipetting or during the transport of pipette tips (hand-held pipette).

[0051] The invention further relates to a pipetting station or a pipetting machine or a laboratory machine with a pipetting device and / or a transport device according to claim 12. The pipetting station or the pipetting machine or the laboratory machine can be used for (automatic) pipetting or for transporting pipette tips. The laboratory machine can be used for automatic pipetting and for transporting pipette tips and can also be used for other processes with liquids, such as for example temperature regulation, mixing, carrying out chemical or biochemical reactions and other physical, chemical or biochemical processes.

[0052] In a pipetting station, a pipetting machine or a laboratory machine, the pipette head can be designed so that it can be fastened to the pipetting station, the pipetting machine or the laboratory machine by means of a fastening device and can be separated therefrom to fasten another pipette head (e.g. for a different size of pipette tip), a gripper tool carrying the labware or another tool thereon. This embodiment is also called a pipetting tool.

[0053] The invention further relates to the use of a pipetting head according to one of claims 1 to 11, a pipetting device according to claim 12 or a pipetting station or a pipetting machine or a laboratory machine according to claim 13, The pipette tips are fastened to their respective attachments on the pipette head, the pipette head moves until each clamped pipette tip is in contact with a receptacle located on the work surface at its lower end; The pipette head moves until the bottom of each clamped pipette tip is a specific distance from the bottom of the vessel. Liquid is dispensed from a reservoir into each clamped pipette tip.

[0054] For several applications, it is desirable to inject liquids into the pipette tip very close to the bottom of the vessel. These applications include, for example, efficient washing steps and optimal recovery of liquids below the phase boundary. In pipetting stations, pipetting machines or laboratory machines, in this case several tolerances exist that affect the final vertical positioning of the tip opening. Especially when used with multichannel pipette heads, especially in designs with sudden change devices (multichannel pipetting tools), it becomes impossible to position the individual pipette tips precisely.

[0055] Using a pipette head with two O-rings per attachment allows unknown tolerance chains due to slight differences in the seating of the pipette tips while maintaining equal metering quality. For this purpose, the pipette tips are first taken out with a pipette head with only one or several channels until they are clamped on all attachments. In this case, the pipette tips are not slid completely on the attachment, i.e. not to the ejector or stop, so they are pushed further upwards on the attachment. The pipette head is then moved and positioned with the lower ends of all clamped pipette tips on a container, from which liquid is removed or dispensed into it. By placing the lower ends of the pipette tips on the container, known and unknown tolerances are compensated. In this case, the pipette tips can be pushed further up on the attachment, to a different extent depending on whether the lower ends come into contact with the container early or late. Then, all clamped pipette tips are immersed in the container until they are slightly removed from the bottom of the container. This creates a small gap between the pipette tip's apical opening and the bottom of the vessel through which liquid can be drawn. This process can be performed fully automatically and does not require any further user intervention. It can be performed while the laboratory machine's program is running. The sheets of clamped pipette tips can be fitted into individual vessel receivers (cavities) with single or multiple cavities or other disposables used.

[0056] According to one embodiment, the pipette head is moved until the lower ends of all clamped pipette tips contact the bottom of the container at the same time, and then the pipette head is moved until the lower ends of all clamped pipette tips are a certain distance away from the bottom of the container. As a result, the gap between the lower ends of each clamped pipette tip and the bottom of the container can be particularly small. According to another embodiment, the pipette head is moved until the lower ends of all clamped pipette tips contact a part of the surface of the container that is not the bottom of the container. As a result, at least the pipette tips can be accurately aligned with the container, and only the tolerance between the position of the contact surface and the bottom of the container is not compensated for.

[0057] According to another embodiment, the pipette head is a multi-channel pipette head and the container is a multi-cavity container, in particular a microtest plate (microtiter plate). The invention is particularly suitable for simultaneously compensating for multiple tolerances between clamped pipette tips and a microtest plate. In this case, the lower end of each pipette tip first comes into contact with the surface of the multi-cavity container or the bottom of a well or other cavity of the multi-cavity container and then moves a short distance away from the bottom of its cavity.

[0058] For example, if the pipette head cannot be moved so that the bottom of each clamped pipette tip touches a container on the work surface because the container contains a liquid that should not touch the pipette tip, the pipette head can be used to push all the clamped pipette tips up to the ejector or to stop them on an attachment, bringing all the clamped pipette tips to the same height. As a result, the tolerance error is reduced, although not to the same extent as if the pipette head was moved so that the bottom of the clamped pipette tip touched the container.

[0059] Furthermore, this object is achieved by a pipette head according to number 1 below or one of the embodiments thereof according to numbers 2 to 15 below.

[0060] A pipette head for a pipetting device, comprising: A holder; at least one attachment held by a holder for clamping to a pipette tip; two elastomeric O-rings held in the attachment; The two O-rings and the attachment are designed such that the pipette tip is tightly secured to the attachment by deformation of the two O-rings only.

[0061] The pipette head according to number 1, wherein the O-ring is manufactured from soft rubber, silicone, or a thermoplastic elastomer.

[0062] A pipette head according to number 1 or 2, wherein the attachment has an axial position fixing device which supports each of the two O-rings at a specific upper position and a specific lower position and is designed to allow deformation of the two O-rings in the radial direction.

[0063] A pipette head according to number 3, wherein the axial position fixing device is a peripheral annular groove on the periphery of the attachment partially accommodating at least one O-ring or one or more protrusions on the periphery of the attachment accommodating at least one O-ring between them.

[0064] A pipette head according to one of numbers 1 to 4, wherein the attachment has at least one conical portion and / or the attachment has at least one cylindrical portion.

[0065] A pipette head according to number 4 or 5, wherein the attachment has an upper cylindrical section at the top, a lower cylindrical section at the bottom, and a conical section therebetween tapering from top to bottom, an upper axial position fixing device between the upper cylindrical section and the conical section, and a lower axial position fixing device between the conical section and the lower cylindrical section.

[0066] A pipette head according to one of numbers 1 to 6, wherein the upper O-ring has a larger inner diameter and / or a larger cross-sectional diameter than the lower O-ring.

[0067] A pipette head according to one of numbers 1 to 7, wherein the cross-sectional diameter of the upper O-ring is larger than the depth of the annular groove and / or the width of the upper annular groove is the same as or larger than the cross-sectional diameter of the upper O-ring and / or the cross-sectional diameter of the lower O-ring is larger than the height of the lower annular groove and / or the width of the lower annular groove is the same as or larger than the cross-sectional diameter of the lower O-ring.

[0068] A pipette head according to one of the numbers 1 to 8, having attachments arranged adjacent to and parallel to one another in one or more rows.

[0069] A pipette head according to one of the numbers 1 to 9, wherein the attachment is firmly connected to the holder.

[0070] A pipetting device or transfer device comprising a pipette head according to one of the numbers 1 to 10.

[0071] A pipetting station or pipetting machine or laboratory machine equipped with a pipetting device and / or a transport device according to number 11.

[0072] Use of a pipette head according to one of the numbers 1 to 10, a pipetting device or transport device according to number 11, or a pipetting station or pipetting machine or laboratory machine according to number 12, The pipette tips are fastened to their respective attachments on the pipette head, the pipette head moves until each clamped pipette tip is in contact with a receptacle located on the work surface at its lower end; The pipette head moves until the bottom of each clamped pipette tip is a specific distance (x) above the bottom of the vessel. Liquid is dispensed from a reservoir into each clamped pipette tip.

[0073] Use according to number 13, wherein the pipette head is moved until the lower ends of all clamped pipette tips simultaneously contact the bottom of the container, and then the pipette head is moved until the lower ends of all clamped pipette tips are a specified distance away from the bottom of the container.

[0074] The use according to number 13 or 14, wherein the pipette head is a multichannel pipette head and the vessel is a microtiter plate.

[0075] The invention will be further described below with reference to the accompanying drawings of exemplary embodiments. [Brief description of the drawings]

[0076] [Figure 1] Front view of the pipette head with clamped pipette tips. [Diagram 2] Rear view of the same pipette head, but without pipette tips. [Diagram 3] Longitudinal section of the same pipette head with clamped pipette tips. [Figure 4]Enlarged longitudinal section of the same pipette head attachment with clamped pipette tips. [Diagram 5] 4 is a diagram showing the mounting force as a function of the path of the pipette head when clamped to a conventional pipette head and when clamped to a pipette head according to the invention. [Figure 6] Schematic diagram showing the tolerance chain and summation of the metrology system. [Figure 7] Schematic showing the attachment of a multichannel pipette head with the ejected pipette tips above the bottom of a microtiter plate. [Figure 8] Schematic diagram showing a pipetting tool in which the pipette tips are individually aligned by contacting the bottom area of ​​a microtiter plate. [Figure 9] Schematic showing a pipetting tool with individually calibrated pipette tips retracted a short distance from the bottom area of ​​a microtiter plate.

[0077] As used herein, the terms "top" and "bottom", "horizontal" and "vertical" refer to the orientation of a pipette head with attachments that are vertically oriented, with the attachments located at the bottom and other parts of the pipette head located at the top.

[0078] In describing different embodiments, the same reference numbers are used for components with the same names.

[0079] According to figures 1 to 2, a pipette head 1 has a housing 2 formed of a front housing case 3 and a rear housing case 4 which join in a vertical plane.

[0080] Eight parallel attachments 5 (pins) for clamping pipette tips 6 protrude vertically downwards from the underside of the pipette head 1 (Figures 3 and 4).

[0081] A band-shaped retaining plate 7 is disposed on the upper surface of the housing 2. A fastening pin 8 protrudes upward from the retaining plate 7.

[0082] According to Figure 3, eight parallel plunger / cylinder units 9 are arranged adjacent to one another in a row in the pipette head 1. Each plunger / cylinder unit 9 has one cylinder 10 in which one plunger 11 is movably arranged.

[0083] Each cylinder 10 has an external thread 12 which allows the cylinder 10 to be screwed into a corresponding internal thread 13 in a through hole 14 in a horizontal lower housing wall 15. Screwing of the cylinders 10 into the lower housing wall 15 is limited by a step 16 on the outer periphery of the cylinders 10, which allows the cylinders 10 to abut against the upper surface of the lower housing wall 15.

[0084] The lower part of the cylinder 10 projects outwardly from the underside of the lower housing wall 15 and forms thereon the attachment 5. The housing 2 thus provides a holder for the attachment 5.

[0085] According to Fig. 4, each attachment 5 has at its upper part an upper cylindrical section 17, at its lower part a lower cylindrical section 18 and between them a conical section 19 tapering from top to bottom. In each attachment 5 an upper axial fixing device 20 in the form of an upper annular groove 21 is located between the upper cylindrical section 17 and the conical section 19 and a lower axial fixing device 22 in the form of a lower annular groove 23 is located between the conical section 19 and the lower cylindrical section 18.

[0086] O-rings 24, 25 made from an elastomer, preferably a soft elastomer, in particular a soft silicone rubber, are inserted into the respective annular grooves 21, 23. Each O-ring 24, 25 is guided on the bottom of the annular groove 21, 23 and has a cross-sectional diameter that is greater than the depth of the annular groove 21, 23 and less than the width of the annular groove 21, 23 in which each O-ring 24, 25 is placed.

[0087] The internal space 26 of each cylinder 10 into which the plunger 11 is inserted from above extends downward to a connection hole 27 on the bottom surface of the attachment 5.

[0088] At the top of each cylinder 10 a liner 28 is arranged, through which the plunger 11 is guided sealingly within each cylinder 10 .

[0089] Each plunger 11 is designed as a cylindrical rod which is inserted at its upper part into and fastened (e.g. glued or pressed) into a central hole 29 of a cylindrical plunger head 30. Each plunger head 30 has a peripheral plunger head annular groove 31 on its outer periphery.

[0090] Below the horizontal upper housing wall 32, a strip-shaped plunger plate 33 is arranged parallel to it. The plunger plate 33 has eight channels 34 on its bottom surface, which are open at the bottom and aligned parallel to one another. Each channel is bordered by two strip-shaped channel walls 35 and two channel shoulders 36 projecting inwardly from the lower ends of the channel walls. Each of the channel walls 35 at the two outer edges of the plunger plate 33 borders an adjacent channel 34 on only one side. Each of the other channel walls 35 borders two adjacent channels 34 on one side. Between the channel shoulders 36, each channel has a grooved opening 37 on the underside of the plunger plate 33.

[0091] The channel 34 has a face opening 38 at the edge of the plunger plate 33, which is aligned parallel to the front and rear faces of the housing 2. The top of the plunger head 30 is inserted into the channel 34 through the face opening 38, so that the channel shoulder 36 snugly engages the plunger head annular groove 31. Thus, by moving the plunger plate 33 vertically, the plunger 11 can move with it in the cylinder.

[0092] An axially movable threaded nut 39 is arranged in the center of the fastening pin 8 and its lower end is rigidly connected to the plunger plate 33 for moving the plunger plate 33 axially in the cylinder 10.

[0093] The fastening pin 8 has at its upper part a cylindrical upper pin part 40. On its outer periphery, the upper pin part 40 supports two partly peripheral connecting elements 41 which are offset by 180 degrees from one another and project radially outwards, by means of which a bayonet connection can be formed. The connecting elements 41 have a slight thread pitch on their bottom side and are fastened with mating connecting elements in the pin holders of the bayonet connection.

[0094] Adjacent to the upper pin portion 40 , the fastening portion 8 comprises a cylindrical central pin portion 42 having an outer diameter larger than that of the upper pin portion 40 .

[0095] Below that, the fastening pin 8 has a conically downwardly expanding lower pin section 43. The lower pin section 43 is firmly connected at its bottom to the retaining plate 7.

[0096] A central bore 44 extends longitudinally of the fastening pin 8. This bore has two diametrically opposed longitudinal grooves 45.

[0097] A sleeve-like threaded nut 39 is inserted into the central bore 44 and is guided at its upper end in the longitudinal groove 45 by two radially projecting wings 46 .

[0098] Furthermore, the spindle 47 is screwed into the threaded nut 39. On its threads 48, the spindle has a protruding bearing pin 49 by means of which it is mounted in a ball bearing 50. The ball bearing 50 is held in a bearing bush 51 of a bearing retainer 52. The bearing retainer 52 has two tabs which protrude diametrically from both sides and which are located on the upper edge of the upper pin part 40 and are fixed there by means of screws.

[0099] A drive 54 is non-rotatably fixed to the part of the bearing pin 49 that protrudes beyond the ball bearing 50 by means of a radially threaded pin 53, and the drive 54 has a radially and axially extending slot 55 on its upper surface for the introduction of a claw-like drive.

[0100] The spindle 47 is supported on the bottom surface of the ball bearing 50. The drive unit 54 is supported on the top surface of the ball bearing 50. Thereby, the spindle 47 is held on the fastening pin 8 so as not to be able to move in the axial direction.

[0101] In one blade 46 of the threaded nut 39, a cylinder pin 56 is fixed which is guided through a groove in a bearing retainer 52. The bearing retainer 52 is oriented parallel to the central axis of the threaded nut 39 and protrudes upward from the fastening pin 8.

[0102] By rotating the drive 54, the spindle 47, which is axially fixed to the fastening pin 8, moves the threaded nut 39, which is axially guided non-rotatably in the fastening pin 8. This causes the plunger plate 33 to move and the plunger 11 to move in the cylinder 10. By rotating the drive 54 in different directions, the plunger 11 can be moved in different directions in the cylinder 10. By scanning the position of the cylinder pin 56, the respective position of the plunger 11 in the cylinder 10 can be measured.

[0103] The fastening pin 8 and the drive arrangement with its integrated threaded nut 39 and spindle 47 correspond to the embodiment of figures 1 to 4 and 6 according to EP 1 407 861 B1. In this respect, reference is made to document EP 1 407 861 B1, the content of which is hereby incorporated by reference into the present application.

[0104] The laboratory machine comprises a bayonet-connected complementary pin holder, which can be coupled to the fastening pin. Preferably, the complementary connection of the laboratory machine corresponds to the tool holder according to figures 7 to 10 of EP 1 407 861 B1. In this respect, reference is made to document EP 1 407 861 B1, the content of which is hereby incorporated by reference into the present application.

[0105] Under the lower housing wall 15, a removal plate 57 is arranged, which further has a through hole 58 through which the pin 5 projects downwards. The removal plate 57 is connected on its long side to a rod assembly 59 guided upwards in a projection 60 of the rear housing case 4. The rear housing case 4 has an opening on its upper surface through which the rod assembly 59 projects from the housing 2. A drive device 61 projects laterally from the upper end of the rod assembly 59. By means of a spring device (not shown), the rod assembly 59 is pressed upwards in the resting state until the removal plate 57 abuts against the underside of the lower housing wall 15. The laboratory machine has a drive device with a drive element, by means of which the drive device 61 can be pressed downwards, so that the removal plate 57 moves downwards and the pipette tip 6 is removed from the attachment 5.

[0106] According to figures 3 and 4, a pipette tip 6 is fastened to the attachment 5. The pipette tip 6 is a tube with a tip opening 62 at its lower end 63 and a mounting opening 64 at its upper end 65. The inner and outer diameters of the pipette tip 6 generally expand from the tip opening 62 to the mounting opening 64. In this embodiment, the pipette tip 6 has several conical regions 64, 65, 66 as well as a cylindrical extension 67 near the upper end 65. In the region of the cylindrical extension 67 and below, the pipette tip has a sealing seat 68 inside.

[0107] According to figures 3 and 4, the attachment 5 of the pipette head 1 is introduced into the pipette tip 6 through the attachment opening 64. The O-rings 24, 25 are arranged at the level of the sealing seat 68. This causes the O-rings 24, 25 to be pressed somewhat radially, so that the pipette tip 6 is firmly clamped and sealed in the attachment 5. Since the O-rings 24, 25 are made of a soft elastic material and the pipette tip 6 would not otherwise come into contact with the attachment 5, the attachment force for attaching the pipette tip 6 to the attachment 5 is relatively small.

[0108] In FIG. 5 the measured fastening forces when fastening a pipette tip as a function of the path of the pipette head are shown next to each other for a pipetting head 1 according to the invention with eight channels and two O-rings 24, 25 in each attachment 5 and for a conventional pipette head with eight channels without O-rings 24, 25 in the attachment. According to the three curves on the left in the figure, when using a conventional pipette head, the fastening force increases sharply until the pipette tip is sufficiently firmly fixed and sealed in the attachment. This occurs when the pipette head is displaced by 2.2 mm with a fastening force of 120 Newtons. According to the curve on the right in the figure, a sufficiently fixed and sealed connection is achieved with a fastening force of about 30 Newtons and a pipette head displacement of 2 mm. In this case only the O-rings 24, 25 are elastically deformed. Beyond this value the fastening force increases sharply, since a deformation of the pipette tip 6 is also required for this.

[0109] Because the attachment force is reduced, the force expelling the pipette tip 6 from the attachment 5 is also reduced.

[0110] The use according to the invention will be described below with reference to Figs. 6 to 9. According to Fig. 6, the laboratory machine 70 has several tolerances that affect the vertical positioning of the tip opening 64 of the pipette tip 6. These tolerances include the positioning tolerances of the multi-axis transport device 71 (robot arm or other transport system). In addition to this, there are tolerances in fixing the pipette head 1 (pipetting tool) to the tool holder 72 held by the multi-axis transport device 71. Furthermore, the manufacturing tolerances of the pipette head 1 must be taken into account. Also, the attachment 5 for removing the pipette tip 6 and the pipette tip 6 itself have tolerances. The microtiter plate 73 and the adapter 74 for positioning the microtiter plate 73 on the working surface 75 (deck) of the laboratory machine 70 have further tolerances. Finally, the working surface 75 itself also has tolerances.

[0111] Especially when using a multi-channel pipette head 1, it is not possible to position the individual pipette tips 6 accurately, since they must all be at the same height.

[0112] For example, in many targeted applications such as next generation sequencing (NGS), this can result in reduced quality due to less efficient wash steps and / or reduced yield from the test material. In the worst case, contaminants can be carried over, e.g., a sample is aspirated under another phase (oil-covered sample) and parts of the overlay are carried over.

[0113] A reduction in the tolerance range reduces the reliability of the process and therefore increases the risk of sample loss. Moreover, the problem is only partially solved, since certain tolerance ranges must not be reached. In most cases, it also increases the direct need to calibrate the equipment very precisely in order to minimize the individual tolerances.

[0114] "Surface teaching" addresses certain tolerances on the system (such as positioning offsets and tool tolerances), but it is very work-intensive and requires a lot of effort from the user. Furthermore, several tolerances are not covered by surface teaching (such as well geometry, microtiter plate seat on adapter, pipette tip geometry, pipette tip seat, tool holder, etc.) because they are done before use and not during the metering process.

[0115] By using two O-rings 24, 25 on each attachment 5, it is possible to tolerate unknown tolerance chains due to slight differences in the seating of the pipette tips while maintaining equal metering quality. The method consists of three sub-steps.

[0116] According to Fig. 7 several pipette tips 6 are picked up on a single-channel or multichannel pipette head 1. When the pipette tips 6 are picked up on the attachment 5 of the pipette head 1, all pipette tips 6 are positioned at the same height and can slide further on the attachment 5 under the action of a small force.

[0117] By moving exclusively vertically under the bottom tolerance range of a surface (such as the bottom of a microtiter plate 73), the pipette tips 6 are pressed to different degrees against each attachment 5. If the attachments 5 are equally aligned vertically, after this step each pipette tip 6 will have an individual height, which is determined by the unknown bottom geometry and the tolerance chain. This is shown in FIG.

[0118] The pipette head 1 is then moved slightly upwards, which creates a gap x between the lower ends 63 of the pipette tips 6 and the surface of the vessel (such as a microtiter plate 73). This gap x is necessary to aspirate liquid into the pipette tips 6 and to avoid the pipette tips 6 becoming blocked. In this way, due to the individual positions of the pipette tips 6, the lower ends of all pipette tips 6 are at the same distance from the vessel surface. This is shown in FIG. 9.

[0119] The advantage of this method is that all (known and unknown) tolerances can be fully compensated for at each weighing step. Moreover, this process is performed automatically, since it can be performed by the laboratory machine 70 without any further effort from the user. The method is performed during operation of the laboratory machine 70, combining the pipette tips 6 with the corresponding individual cavities of the single-cavity and multi-cavity vessels used, such as microtiter plates 73, respectively. [Explanation of symbols]

[0120] 1 Pipette Head 2 Housing (retainer) 3,4 Housing Case 5 Attachment (pin) 6 Pipette Tips 7 Fastening plate (retaining plate) 8 Fastening pin 9 Plunger / Cylinder Unit 10 Cylinders 11 Plunger 12 Male thread 13 Female thread 14 Through hole 15 Housing wall 16 steps 17 Upper cylindrical section 18 Lower cylindrical section 19 Cone section 20 Upper shaft position fixing device 21 Upper annular groove 22 Lower shaft position fixing device 23 Lower annular groove 24,25 O-ring 26 Interior Space 27 Connection hole 28 Liner 29 holes 30 Cylindrical Plunger Head 31 Plunger head annular groove 32 Housing wall 33 Plunger Plate 34 Channels 35 Channel Wall 36 Channel Shoulder 37 Grooved opening 38 Front opening 39 Threaded Nut 40 Upper pin part 41 Connection elements 42 Center pin 43 Lower pin part 44 holes 45 Vertical groove 46 Feather 47 Spindle 48 Screw 49 Bearing pin 50 ball bearings 51 Bearing bush 52 Bearing holder 53 Screw pin 54 Drive unit 55 Slots 56 Cylinder Pin 57 Removal Plate 58 Through hole 59 Rod Assembly 60 Protrusion 61 Drive unit 62 Tip opening 63 Lower end 64 Mounting opening 65 Upper end 64,65,66 Cone Area 67 Cylinder Extension 68 Sticker Sheet 70 Experimental Machine 71 Multi-axis transfer device (robot arm) 72 Tool holder 73 Microtiter Plates 74 Adapter 75 Work Surface

Claims

1. A pipetting head for a pipetting device, comprising at least one pipette tip, A holder (2), at least one attachment (5) held by said holder (2) for clamping to a pipette tip (6); two elastomeric O-rings (24, 25) held in said attachment (5); At the points of contact with the O-rings (24, 25), the inner diameter of the sealing seat (68) of the pipette tip (6) is smaller than the outer diameter of the corresponding O-ring (24, 25), so that the O-rings deform while sliding, and firmly clamp the pipette tip (6) on the attachment (5); A pipette head with at least one pipette tip, characterized in that the O-rings (24, 25) are configured to deform while sliding so that the sealing seat (68) abuts against the attachment (5) without directly contacting the attachment (5) or without applying a force to the pipette tip (6) that would deform the pipette tip.

2. 2. A pipette head with at least one pipette tip according to claim 1, wherein the inner diameter of the sealing seat (68) of the pipette tip (6) at the point of contact with an O-ring (24, 25) is smaller than the outer diameter of the corresponding O-ring (24, 25), and the inner dimensions of the sealing seat (68) of the pipette tip (6) are determined so that when the pipette tip (6) is firmly fixed to the attachment (5) by deformation of the two O-rings (24, 25), the sealing seat (68) abuts against the attachment (5) without directly contacting the attachment (5) or without applying a force on the pipette tip (6) that deforms the pipette tip (6).

3. 3. A pipette head with at least one pipette tip according to claim 1 or 2, wherein said O-rings (24, 25) are made from soft rubber, silicone or a thermoplastic elastomer.

4. 4. A pipette head with at least one pipette tip according to claim 1, wherein the attachment (5) has an axial position fixing device (20, 22) which supports each of the two O-rings (24, 25) at a specific upper position and a specific lower position and is designed to allow the two O-rings (24, 25) to deform in a radial direction.

5. 5. A pipette head with at least one pipette tip according to claim 4, wherein the axial position fixing device (20, 22) is a peripheral annular groove (21, 23) on the periphery of the attachment which partially accommodates at least one O-ring (24, 25) or is one or more protrusions on the periphery of the attachment which accommodate at least one O-ring (24, 25) between them.

6. 6. A pipette head comprising at least one pipette tip according to claim 1, wherein the attachment (5) has at least one conical portion (19) and / or the attachment (5) has at least one cylindrical portion (17, 18).

7. 7. A pipette head with at least one pipette tip according to claim 5 or 6, wherein the attachment (5) has an upper cylindrical section (17) at an upper part, a lower cylindrical section (18) at a lower part, a conical section (19) tapering from top to bottom therebetween, an upper axial position fixing device (20) between the upper cylindrical section (17) and the conical section (19), and a lower axial position fixing device (22) between the conical section (19) and the lower cylindrical section (18).

8. 8. A pipette head comprising at least one pipette tip according to claim 1, wherein the upper O-ring (24) has a larger inner diameter and / or a larger cross-sectional diameter than the lower O-ring (25).

9. 6. A pipette head comprising at least one pipette tip according to claim 1, wherein the cross-sectional diameter of the upper O-ring (24) is greater than the depth of the upper annular groove (21) and / or the width of the upper annular groove (21) is the same as or greater than the cross-sectional diameter of the upper O-ring (24) and / or the cross-sectional diameter of the lower O-ring (25) is greater than the height of the lower annular groove (23) and / or the width of the lower annular groove (23) is the same as or greater than the cross-sectional diameter of the lower O-ring (25).

10. 10. A pipette head comprising at least one pipette tip according to claim 1, having attachments (5) arranged parallel and adjacent to one another in one or more rows.

11. Pipette head with at least one pipette tip according to one of claims 1 to 10, wherein the attachment (5) is rigidly connected to the holder (2).

12. A pipetting device comprising a pipette head (1) having at least one pipette tip according to one of the claims 1 to 11.

13. A pipetting station or pipetting machine or laboratory machine (70) equipped with a pipetting device according to claim 12.

14. Use of a pipetting head (1) with at least one pipette tip (6) according to one of claims 1 to 11, or of a pipetting device according to claim 12, or of a pipetting station or a pipetting machine or a laboratory machine (70) according to claim 13, Pipette tips (6) are fastened to respective attachments (5) of the pipette head (1), said pipette head (1) is moved until the lower end (63) of each clamped pipette tip (6) comes into contact with a receptacle (73) provided on a working surface (75); the pipette head (1) is moved until the lower end (63) of each clamped pipette tip (6) is a specific distance (x) from the bottom of the container (73); Use, characterized in that liquid is injected from said container (73) into each clamped pipette tip (6).

15. 15. The use according to claim 14, wherein the pipette head (1) is moved until the lower ends (63) of all the clamped pipette tips (6) simultaneously contact the bottom of the container (73), and thereafter the pipette head (1) is moved until the lower ends (63) of all the pipette tips (6) are a certain distance away from the bottom of the container (73).

16. Use according to claim 14 or 15, wherein the pipette head (1) is a multichannel pipette head and the vessel (73) is a microtiter plate.

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