DE4330562A1 - Plastic pipette - Google Patents

Description

The present invention relates to a pipette with a pipette body and a pipette piston, this pipette acting as a liquid detector can be used, either the pipette body or the pipette piston is electrically conductive.

Such a pipette is e.g. B. described in EP-A-0 226 867. Execution Such a plastic syringe usually consists of two different ones Materials, e.g. B. polypropylene (PP) and polyethylene (PE). These materials will if necessary, a lubricant in the form of e.g. B. oleic acid amide is added good sliding between the pipette piston and body is achieved. To be exact To achieve volume absorption and delivery, the body is preferred from the mechanically more stable material (PP). Since the conductivity z. B. by If graphite is embedded in the plastic, it is obvious that To make pipette pistons from the conductive material, so the possibility of optical control of the liquid sucked into the pipette not by the Coloring of the pipette body is impaired.

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

If you place such a pipette in automatic analyzers such as z. B. in medicine diagnostics are used, these pipettes mainly come in contact with solutions that contain detergents, among other things. Through this Detergents, the sliding layer is washed off in a short time, which means that the sliding properties between the pipette piston and the pipette body be greatly disturbed. The sudden increase in static or sliding friction leads to uncontrolled, jerky flow rates when delivering rivers from the syringe. This allows parts of the liquid to be transferred spray around uncontrollably, which leads to incorrect dosages.  

Detergents for use in such solutions and the ones used Detergent concentrations are known to the person skilled in the art.

The object underlying the present invention was therefore to create a Pi to find pette that does not have the above disadvantages.

This task was solved in that pipette body and pipette piston due to a well lubricated, water-insoluble layer that does not or only insignificant, preferably not, of detergent-containing solutions is attacked, separated, the conductivity of the pipette piston preserved.

Such a separation can be achieved by various measures.

The pipette according to the invention therefore preferably has an electrical one conductive pipette piston, which is essentially made of plastic and an essentially transparent pipette body, pipette pistons and Pipette body at least in the areas in which they are in contact a layer of a sufficiently lubricious material is separated.

According to the invention is also a pipette in which the pipette piston is conductive - for the invention, however, is fundamentally irrelevant which part the pipette is conductive.

For the production of pipette bodies, for. B. PPX 655 natural (from HOECHST AG, Frankfurt, Germany), polypropylene VC 10 64K (NESTE Chemicals) or Daplen KS 131 S (from PCD) can be used. For the production of Pipette piston can e.g. B. Polycam PP 2261 EG (HOECHST AG, Frankfurt, Germany) or Lupolen® V3510 K 80% or Lupolen® 6031 M20% (Fa. BASF, Ludwigshafen, Germany) can be used.

In a preferred embodiment, the pipette is one of these called "positive displacement pipette" (dead volume-free pipette), the doors between pipette body and pipette piston by coating the Pipette body and / or the pipette piston preferably by silicone oil  at temperatures above 50, most preferably at temperatures of about 70 ° C takes place. Suitable silicone oils are known per se to the person skilled in the art, e.g. B. Baysilone® oil MPH 1000 or paste (Bayer, Leverkusen, Germany) and oil AK 12500 (from WACKER).

In a further preferred embodiment, this sliding layer is covered by a Coating with materials known per se to the person skilled in the art, such as, for. B. one liquid PTFE product, e.g. B. VYDAX® 500 or OSIXO TS (Costenoble) or a chemically related product.

In a further preferred embodiment, this sliding layer is thereby generates that between the piston and body a seal, for. B. an O-ring, so turned is added that the piston and body no longer touch each other directly. Suitable Materials are known per se to the person skilled in the art. Preferably the ring made of silicone rubber, rubber or another plastic that is low Has friction produced.

In a further preferred embodiment, a, preferably mechanically self-supporting insert made of a special lubricious plastic, e.g. B. PTFE inserted.

In the following he the invention with reference to the accompanying drawings purifies. Show it:

View of Figure 1 partially broken away of an embodiment of a pipette according to the invention.

Fig. 2 embodiment with a sealing lip made of the piston material;

Fig. 3 preferred embodiment with O-ring made of slidable material;

Fig. 4 preferred embodiment with attached, slidable sealing lip;

Fig. 5 preferred embodiment with a self-supporting inner coating made of lubricious material.

The pipette according to Fig. 1 consists of a pipette body (3) with the inner side (4) and a pipette piston (2), wherein the pipette piston (2) consists of electrically conductive homemade plastic and the piston (2) with a sealing lip (7) is provided. The pipette piston ( 2 ) has an end section ( 1 ) consisting essentially of two disks, on which the pipette piston ( 2 ) can be manipulated in an automatic analyzer with the aid of a receiving device. The pipette body ( 3 ) has a predominantly disc-shaped end section ( 8 ) which is used for manipulation in the automatic analyzer.

Claims (7)

1. A pipette in the piston ( 2 ) and / or body ( 3 ) are electrically conductive, characterized in that between the piston ( 2 ) and body ( 3 ) at least at the location of the sealing lip ( 7 ) a water-insoluble sliding layer, the is not or only insignificantly attacked by detergent-containing solutions. 2. The pipette according to claim 1, characterized in that it is a is a dead volume-free pipette. 3. The pipette according to claim 2, characterized in that the pipette piston ( 2 ) is electrically conductive. 4. The pipette according to claim 3, characterized in that the sliding layer consists of silicone oil, preferably at about 50 to 150 ° C, is particularly preferably applied at about 70 ° C. 5. The pipette according to claim 3, characterized in that the sliding layer is an O-ring ( 5 a) made of a lubricious material. 6. The pipette according to claim 3, characterized in that the sliding layer is a sealing lip, the whole or at least in its outer periphery a lubricious material. 7. The pipette according to claim 3, characterized in that the sliding layer consists of an insert ( 6 ) made of a lubricious material.