Plastic pipette.

p0001The present invention relates to a pipette having a pipette body and a piston pipette, said pipette is used as a detector fluid, wherein either the pipette body and the pipette piston is electrically conductive.

p0002Such a pipette is z. B. EP-A-0 226 867. The execution of such a plastic syringe is usually made of two different materials, for. Example, polypropylene (PP) and polyethylene (PE). These materials will be a lubricant in the form of z. B. oleamide added as needed to produce a good sliding between Pipettenkolben- and body is achieved. To obtain an accurate Volumenaufnahme- and royalty, the body preferably of the mechanically stable material (PP) is produced. Since the conductivity z. B. is achieved by incorporation of graphite into the plastic, it is natural to make the pipette pistons of the conductive material, so that the possibility of visual inspection of the absorbed into the pipette fluid is not affected by the coloration of the pipette body.

p0003Due to the design such pipettes have at least one sealing lip which comes into contact with the media to be pipetted.

p0004Putting such a pipette in Analysenaut omaten as they are such. As used in medical diagnostics, a, these pipettes are predominantly with solutions in contact, containing, inter alia detergents. Through these detergents, the sliding layer is washed off in a short time, with the result that the sliding properties between the pipette piston and the pipette body are severely disrupted. The so abruptly increased adhesion or friction leads to uncontrolled, jerky Ausflußgeschwindigkeiten in the delivery of fluids from the syringe. This allows parts of elements and fluids uncontrolled splashing around, resulting in incorrect doses.

p0005Detergents for use in such solutions and detergent concentrations used therein are known to the skilled artisan.

p0006The the present object underlying the invention was therefore to find a pipette which does not have the above disadvantages.

p0007This object was achieved in that pipette body and the pipette pistons are separated by a good lubricious water-insoluble layer which does not or only slightly, preferably not attacked by detergent-containing solutions, the conductivity of the pipette piston is retained.

p0008Such separation can be achieved by various measures.

p0009The pipette according to the invention thus has preferably an electrically conductive pipette piston, which is essentially made of plastic, and a substantially transparent pipette body, pipette piston and pipette body, separated at least in the areas where they are in contact by a layer of a sufficiently lubricious material are.

p0010The invention also relates a pipette in the pipette body is conductive - for the invention, it is generally not of great significance, which part of the pipette is conductive.

p0011For the production of pipette bodies can, for. Example, PPX 655 nature (Fa. Hoechst AG, Frankfurt, Germany), polypropylene VC 10 64K (Fa. NESTE Chemicals) or Daplen KS 131 S (Fa. PCD) are used. For the production of pipette piston can for. B. Polycam PP used in 2261 EC (Fa. Hoechst AG, Frankfurt, Germany) or Lupolen.RTM V3510 K 80% with Lupolen.RTM 6031 M 20% (Fa. BASF, Ludwigshafen, Germany).

p0012In a preferred embodiment, when the pipette to a so-called "positive displacement pipette" (dead volume pipette), the separation between the pipette body and the pipette piston through a coating of the pipette body and / or the pipette piston preferably by silicone oil at temperatures above 50, very preferably takes place at temperatures of about 70 ° C. Suitable silicone oils are known to those skilled in itself, eg. B. Baysilone® oil MPH 1000 and Paste (Fa. Bayer, Leverkusen, Germany) and oil AK 12500 (Fa. WACKER).

p0013In a further preferred embodiment example, this overlay known by a coating to the person skilled in the materials such. A liquid PTFE product, z. B. VYDAX®500 or OSIXO TS (Fa. Costenoble) or a chemically related product generated.

p0014In a further preferred embodiment, this overlay is generated by the fact that between the piston and a seal body z. B. an O-ring is inserted so that the piston and the body can no longer touch directly. Suitable materials are known to the skilled worker. Preferably, the ring is made from silicon rubber, rubber or other plastic having a low friction.

p0015In a further preferred embodiment, PTFE is in the pipette body a, preferably mechanically self-supporting insert made of a particularly lubricious plastic such. Inserted.

p0016In the following the invention will be explained in more detail with reference to the accompanying drawings. Show it:<ul><li>Figure 1: partially broken away view of an embodiment of a pipette according to the invention;</li><li>Figure 2: embodiment with sealing lip of the piston material;</li><li>Figure 3: preferred embodiment with O-ring made of slippery material;</li><li>Figure 4: preferred embodiment with an attached, sliding sealing lip;</li><li>Figure 5: preferred embodiment with a self-supporting internal layer of slippery material.</li></ul>

p0017The pipette of Figure 1 comprises a pipette body (3) with the inner surface (4) and a pipette piston (2), the pipette piston (2) of electrically conductive homemade plastic and provided the piston (2) with a sealing lip (7) is. The pipette piston (2) has a substantially consisting of 2 slices of end portion (1), on which the pipette piston (2) can be manipulated by means of a pickup device in an automatic analyzer. The pipette body (3) comprises a mainly disc-shaped end portion (8), which are used for handling in the analysis machine.