EP0264704B1 - Pipetting device provided with a conical adapter for a pipette tip, and pipette tip for such a device - Google Patents

Abstract

A pipette has a male cone on which a pointed nozzle can be pushed on with its female cone. This point includes a filter which rests with its lower face on three internal bosses. This filter can be made partly of inorganic material, topped by a layer of Kieselguhr or by a layer of polyester or acetate fibres. This filter is pref. coated with bacterial, fungicidal, or viricidal agents.

Description

The invention relates to a pipetting device with a push-on cone for a pipette tip according to the preamble of claim 1.

Filters for use with plastic tips of micropipettes are known from US Pat. No. 4,059,020. The filters are made of porous plastic or metal and can be brought into contact with the tip when the liquid sample is taken up, so that it is filtered at the same time. This is a pure liquid filter, which is after the sample intake and before the discharge of the filtered liquid is removed. It is included that tips of different sizes and shapes are used. The filter device consists of a holder for a filter which can be plugged onto a pipette tip, the passage at the pluggable end being cylindrical or conical and thus being able to be used on various pipette tip shapes. The porous liquid filter is aligned with the passage in a filter space that is widened relative to the passage.

From FR-A-2 220 135 a pipetting device of the type mentioned at the outset is known, which has a disk-shaped filter. The filter should allow a fine passage of air and prevent the passage of microorganisms or viruses. For this purpose it can consist of a polymeric material such as nylon, polypropylene or polytetrafluoroethylene, of a fiber material such as glass wool or light-absorbing cotton or synthetic fiber or of a synthetic polymeric material with channels therein. However, the effect of such homogeneous filters is not equally satisfactory for all impurities and can be inadequate, at least for parts of them, particularly in the presence of very different microorganisms or viruses.

The invention has for its object to improve a pipetting device of the type mentioned in such a way that an improved cleaning of continuous air from aerosols, bacteria, fungi and fungal spores takes place, the filter being easy to use at a particularly effective location.

This object is achieved by claim 1. Refinements are specified in the subclaims.

The filter can be effective in two directions, so that both contamination of the interior of the pipette located above the filter level and back contamination from the upper interior of the pipette to the absorbed liquid is prevented.

Such a filter has considerable advantages in use because the passages of liquid and air are opposed to various influences, also depending on the pressure change.

From this point of view, disks of different densities or different heights are stacked on top of one another. The filter effect can be determined by the length of the passages to be influenced.

The progressive filter effect is useful because a filter element is created with regard to substances to be filtered, which enables a smooth passage with certain substances. In the case of substances with differing properties, their gradual filtering out is provided, depending on the content being possible by means of the progressive filtering action to match specific content. A filter element with a progressive filter effect over the filter length is advantageous, in which individual filter parts or disks can be exchanged. In this way, a filter element can also be matched to different substances. The range between 0.2 and 0.45 µm is included as the effective pore size.

In a preferred embodiment, the filter arrangement or design basically has a coating of the filter material with special bactericidal, fungicidal or virucidal active substances as well as with generally disinfectant substances.

A hydrophobic coating, for example in the form of a silanized one, can be useful for special fields of application Surface of the filter material may be provided. This represents an inexpensive version of an aerosol filter because moisture that is carried along is rejected.

In this context, it is included that the filter material can be provided with an adhesive coating made of a reactive material which binds special portions of the continuous medium and then also exits.

In a preferred embodiment, using a filter with micropores in the direction of passage, this filter is designed as a section of inorganic material in connection with a filter disk made of sintered diatomaceous earth. This composition also opens up possibilities for adaptation.

Another advantageous embodiment of the filter has a mushroom-like design with a stem that can be inserted into the passage of the plug-on cone. Such a filter is also easy to handle because the mushroom head of the filter can be handled as a handle part. The stem itself represents a special filter element which, according to the above statements, in particular consists of several layer-like sections with a progressive filter effect can be.

For all versions it is advantageously included that the filter with an indicator additive for liquid contact, e.g. in the form of cobalt compounds. This feature is particularly advantageous in connection with a filter consisting of several layers and a progressive filter effect, in order to bring about a change in color in the event of a one-time liquid contamination or with multiple dosing, in particular with gradual entry of aerosols, i.e. if the dose is applied several times, introduce a slow color change in order to make the level of aerosol contamination recognizable. This results from the discoloration caused by the addition of indicators depending on layers, if a multi-layer version is provided.

Such coated filter materials require absolute dry storage. Dry packaging is therefore also included in connection with the other coatings mentioned, optionally in the form of a blister pack with entries for keeping the contents dry.

Fig. 1

in schematischer Seitenansicht eine Pipettiervorrichtung mit einer Aufsteckspitze, zum Teil im Schnitt;

Fig. 2

eine Seitenansicht einer Aufsteckspitze im Schnitt unter Einbeziehung einer ganz besonderen Ausgestaltung einer solchen Pipettenspitze, jedoch mit einem eingebrachten Filterelement;

Fig. 3

eine Draufsicht auf Fig. 2 im Schnitt längs der Linie III-III;

Fig. 4

eine der Fig. 2 entsprechende Seitenansicht einer Aufsteckspitze anderer Ausführung;

Fig. 5 bis 7

Seitenansichten schematischer Art, teilweise im Schnitt für verschiedene Ausgestaltungen eines Filterelementes;

Fig. 8

das untere Ende einer Pipettiervorrichtung mit einem Aufsteckbonus in besonderer Ausgestaltung in schematischer Darstellung;

Fig. 9

das untere Ende einer Pipettiervorrichtung mit einem einteiligen Aufsteckkonus üblicher Ausführung in Verbindung mit einer Pipettenspitze unter Zwischenschaltung einer Filteranordnung in Seitenansicht und im Schnitt;

Fig. 10

das schematisch dargestellte untere Ende einer üblichen Ausführung einer Pipettiervorrichtung mit einer besonderen Ausgestaltung einer Filterausführung.

The invention is described below using exemplary embodiments explained, which are shown in the drawing. The drawing shows:

Fig. 1

a schematic side view of a pipetting device with a push-on tip, partly in section;

Fig. 2

a side view of a push-on tip in section including a very special embodiment of such a pipette tip, but with an inserted filter element;

Fig. 3

a plan view of Figure 2 in section along the line III-III.

Fig. 4

one of Figure 2 corresponding side view of a push-on tip of another embodiment;

5 to 7

Side views of a schematic type, partly in section for different configurations of a filter element;

Fig. 8

the lower end of a pipetting device with a slip bonus in a special embodiment in a schematic representation;

Fig. 9

the lower end of a pipetting device with a one-piece plug-on cone of conventional design in connection with a pipette tip with the interposition of a filter arrangement in side view and in section;

Fig. 10

the schematically shown lower end of a conventional design of a pipetting device with a special design of a filter design.

In all figures, the same parts are identified by the same reference numerals.

A pipetting device 1 according to FIG. 1 has a device body 2, for example of a cylindrical type, with an actuating lever 3 which leads upwards for driving a piston 4 in a cylinder space 5, from which a capillary-like passage 6 to the end face 7 of a plug-on cone 8 extends. It goes without saying that for the arrangement of the actuating lever 3 and the piston 4, additional guide and also latching means and adjusting devices, which can be actuated by a hand lever 9, are provided for different stroke sizes.

Such pipetting devices are known. For example, reference is made to DE P 25 49 477.

A pipette tip 10 is placed on the plug-on cone, which is open at its lower end at 11 and can have a wall reinforcement 12 on the outside at its upper further end, so that a secure fit is ensured with the plug-on cone 8 in the same shape.

A filter 14 is arranged in the area 13, which includes the lower end of the pipetting device 1 with the plug-on cone and also the upper end of the pipette tip 10 below the plug-on cone.

Several options are included for the arrangement of the filter.

According to FIGS. 2 and 3, the filter 14 is designed conically in accordance with the conicity of the pipette tip 10 and arranged in the pipette tip 10.

2 and 3, the positioning aid is designed in the form of inward projections 15-17 which the edge of the lower surface 18 of the filter creates. A special pressure can be provided here. Preference is given to the design of the projections 15-17 with a roof-shaped ridge 19-21 arranged on the top, which makes it easier to insert the filter for tight wall-mounting on the wall of the pipette tip by pressing lower edge sections onto the ridges which penetrate and thus also fix the position in the circumferential direction. An embodiment of the projections 15-17 in a narrow form as vertically arranged cutting edges is preferred, on which the filter easily fits under external influences, whether during insertion or under operational influences, by the filter being more or less deep over the cutting edges penetrates.

2 also shows that the pipette tip 10 has a wall section 54 of lesser wall thickness and is expandable in this area when the pipette tip 10 is made of elastic material. This has the advantage that an inserted filter causes an elastic expansion of the walls of the plug-on cone and thus finds a firm fit, the lower edge, for example at 55 of the particularly elastic wall section 54, also forming an abutment limit for an inserted filter.

Irrespective of this, a fit of an inserted filter is included not only in such a last-described embodiment, but also in an embodiment of a pipette tip with a uniformly solid wall part throughout.

4, the positioning aid consists of an inwardly directed ring flange 22 which forms an edge-side contact surface for the filter. In this embodiment, it goes without saying that this filter, which is designed as a cone section, is designed with oversize to such an extent that when the ring flange is reached, it finds a sealing contact on the inner wall of the pipette tip 10.

5 to 7 different designs of the filter are shown. The conical design shown is advantageous for use in the solutions described, but is not in itself necessary.

According to the invention, according to FIG. 5, a filter 23 consists of several layers 24 to 27, which are designed in disks. This is a feature because the discs can have different filtering properties, so that a progressive filtering effect then arises. For example, panes of the same height can have different densities, so that in Different filter effects arise because continuous media come into contact with wall parts of capillary passages several times with increasing density. This can be used to trigger reactions, but in itself also for an increased filter effect, namely when the suction or pressure force reaches or exceeds a certain level.

5, the disks have 24 to 27 different heights. When designing panes with the same density, the different heights result in substantially proportionally different passage difficulties, i.e. Filter effects. Such an embodiment is preferred if the filter effect is to be accompanied by selectively acting influences. These influences change in their reactivity depending on the height of the individual panes, i.e. the activity increases when the slice is thicker. Design is also possible in this way.

Such an embodiment is preferred if at least individual parts of the filter are provided with a discolouring indicator additive for liquid contact. The further variation that the indicator addition for individual disks 24 to 27, if necessary, is also included of the same height, can be of different strengths.

Fig. 6 shows another embodiment of a filter with a section 28 made in particular of inorganic material, e.g. Glass fiber material or rock wool, which has essentially axial microcapillary-like passages 29. Such a section is in particular provided with a filter disk 30, which is made of cellulose or a corresponding plastic, which advantageously does not react with the substance to be treated, but has special filter properties due to its labyrinthine twisted passages. For this, reference is made to the above explanations for the material and the pore size.

FIG. 7 shows a corresponding solution with a section 31 and a filter disk 30. Starting from the lower inlet opening 32, the section 31 has labyrinthine passages, one of which is designated 33. These passages are delimited by baffles 34 to 37 which form wall parts for the passages. These baffles can consist of a reactive material, such as adhesive coatings, which binds special portions of the continuous medium and, apart from the deposit, in the process due to the deflection, and thus exits the medium. In spite of the filter disk 30, this includes the fact that primarily an aerosol filter is created, because then the filter disk 30 can also have special reactions in the event of fluid access.

FIG. 8 shows another solution in which, with reference to FIG. 1, the push-on cone 8 consists of two parts 38 and 39. As a result, this slip-on cone is divisible. The part 38 located on the device body 2 of the pipetting device is penetrated by the capillary passage 6 over a section of its length, but has a free space under a transverse wall 40 located therein.

The other part 39 is fastened to the part 38, for example by a screw connection 41 with threads. The part 39 is designed as a hollow shell and is only closed at the bottom by the wall part 42 with the capillary passage 43. In the cavity 44 of the hollow part 39 there is a filter 45 of the type described. This filter is easy to replace because the lower part 39 of the plug-on cone is freely accessible and can be unscrewed. In this arrangement, an elastic sealing ring 56 is expediently included, which is an adaptable assembly enabled under tension. A plug connection with a bayonet lock is not excluded.

8, the pipetting device retains its shape for the use of customary known pipette tips.

The same applies to FIG. 9. Here, handling is made even easier because a conical plug-in filter element 46 can be placed on the outside of the plug-on cone 8, which is equipped on the inside with a filter 47.

Due to the conical design, the further end 48 can easily be placed on the push-on cone. This further end can also be made elastic. The pipette tip 10 can be plugged onto the lower, narrower end 49 because the conicity remains the same as a result of the embodiment described.

In this respect, the plug-in filter element 46 is a particularly advantageous embodiment for the arrangement of the filter in the area 13 according to FIG. 1.

The handling of the Vorsteck filter element can by a flange-like grip projection 53 arranged on the outside and in the upper region can be facilitated, which is expediently designed as a polygon.

Referring to Fig. 8, in which a filter 45 is provided in the slip cone, i.e. on the pipetting device 1, FIG. 10 shows a further and different advantageous embodiment in that a filter 50 is not arranged inside the plug-on cone 8, but outside at its tip. This is achieved by a mushroom-shaped design which has a head piece 51, in particular a hemispherical shape with a base corresponding to the lower surface of the plug-on cone, and a stem 52 which can be inserted into the capillary passage. Such a filter can be easily handled on the head 51. The stem 52 per se and also in relation to the head piece 51 can be made of filter materials of various effects. A commercially available pipette tip is placed on the cone.

Claims (7)

1. Pipetting device comprising a conical adapter for a pipette tip, a piston chamber which communicates with a passage of the conical adapter, for reciprocating motion of a piston, a pipette tip and a filter arranged in the pipette tip, characterized in that the filter (14, 23, 50) consists of an aerosol filter and is detachably arranged in a region (13) defined by the lower end of the pipetting device (1), including the conical adapter (8), and the upper end portion of the pipette tip (10) arranged below the conical adapter, and in that the filter (14, 23) includes a plurality of superimposed disc-like layers (24-27) of different, particularly decreasing permeability, and the discs (layers 24-27) differs in density and/or height so as to provide progressive filtering action.
2. Pipetting device according to claim 1, characterized in that the filter material of the filter has a coating comprising agents having specific bactericidal, fungicidal or virucidal activities, and substances having a generally desinfecting acitivity.
3. Pipetting device according to claim 1 or 2 comprising a filter having microspores in passage direction, characterized in that the filter has a portion (28) of anorganic material in connection with a filter disc (30) of sintered diatomite.
4. Pipetting device according to one of the claims 1 to 3, characterized by a filter with a mushroom-shaped formation having a stem (52) which is slidable into the passage (6) of the conical adapter (8).
5. Pipetting device according to claim 4, characterized in that the mushroom-shaped, particularly semi-spherically shaped formation comprises a head so as to form a handle.
6. Pipetting device according to one of the claims 1 to 5, characterized in that the filter (14, 23, 50) is provided with an indicator additive for liquid contact.
7. Pipetting device according to claim 6, characterized in that the indicator additive includes cobalt compounds so that the additive reacts with sudden color change to a single occuring contamination of liquid, or with a slow color change to multiple dosages, particularly to a gradual entry of aerosols.

Images