Patent Application
20070148040
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1. Field of the Invention
This invention relates to the field of liquid extraction and dispensing devices in general and pipettes in particular.
2. Description of the Related Art
A pipette is typically used to transfer liquids from one container to another. In a typical pipette operation the user will insert the pipette into a test tube, a centrifuge tube, or a microcentrifuge tube (See
One of the difficulties of liquid extraction using a pipette involves test tubes, centrifuge tubes, or microcentrifuge tubes; that have both a liquid portion and a solid or semi-solid portion. The solid portion is typically formed when a liquid sample is centrifuged. The centrifuge process creates a lighter liquid portion called the supernatant and a heavier solid portion called a pellet. Some extraction processes require the user to only remove the supernatant of the test tube, the centrifuge tube, or the microcentrifuge tube, without disturbing the pellet. This is a serious enough problem that common introductory biology classes advise students to be aware of this problem (see http://www.ruf.rice.edu/-bioslabs/studies/sds-page/gellabl.html ), stating ‘It is often difficult to see where the supernatant ends and the pellet begins, thus there is a risk of sucking the membranes up as the supernatant is discarded. If it becomes difficult to distinguish where the pellet begins, one can stop part way through the removal of supernatant, resuspend everything, and recentrifuge’).
Clearly a problem can exist during the manual extraction of the supernatant when a pellet is present.
In a particular example, the process of PCR extraction involves extracting the supernatant and preserving the pellet. The type of pipette used in PCR extraction is usually a polypropylene pipette. The polypropylene pipette typically consists of a clear or translucent pipette coupled with an extraction syringe or built in plunger unit. The extraction syringe or built in plunger unit creates the negative air pressure necessary to draw liquids through the clear or opaque pipette. The pipette is inserted into a tube (see Eppendorf, Inc). The tube itself is usually made of polypropylene and is clear or translucent allowing the user to see the supernatant and the pellet.
One of the difficulties in the extraction process involves insertion of the pipette into the tube. The tube is made of a clear or translucent plastic with little surrounding contrast. The pipette likewise is made of a clear or translucent plastic. The difficulty arises due to the lack of contrast between the two materials. When a person holds the tube in one hand and inserts the pipette into the tube, it is difficult to see the end of the pipette. The problem is that if the tip of the pipette is improperly positioned then there is a risk of touching the pellet with the tip of the pipette, thereby destroying the experiment.
For example, there are a number of manufacturers and distributors of pipettes and transfer pipettes, with or without tubes in a disposable and non-disposable fashion. Eppendorf produces a number of pipettes (See http://www.eDpendorfna.com/products/?LVL=4&PHDPNK=002006071) that are used with the 0.2 and 0.5 ml tubes (See http://www.eppendorfna.com/products/PCR tube de.asp?PHDPNK=00300605904 8). Also, Diagger, VWR, and other laboratory vendors are distributors of these tubes and pipettes.
U.S. Pat. No. 6,955,180 (2005) to Kocherlakota, et al. describes color coded gangs of holes which are color coded, but fails to describe a pipette tip that is color coded. U.S. Pat. No. 6,852,283 (2005) to Acosta , et al. describes guide holes that are color coded, but, does not describe the color coding of pipettes themselves.
U.S. Pat. No. 5,344,036 (1994) to Stanescu, et al. describes a colorized disk on a vial, but does not describe the disk in conjunction with a pipette that is colored
U.S. Pat. No. 5,218,875 (1993) to Volpe, et al. describes color on a pipette assembly, but specifically states that the tip should remain clear and is simply used for identification purposes.
Currently there has been no apparatus or methods created to reduce the risk of disturbing the pellet during manual or mechanical extraction of liquids using a pipette.
Whereas the pipette is simply one type of liquid dispensing devices that are inserted into containers for the purposes of extracting liquids. There are many other types of devices that operate in a similar fashion to pipettes.
It is an object of this invention to an easier means for position liquid dispensing or extraction devices in containers where there is currently little contrast between the tip of the liquid dispensing or extraction devices, the container, and the liquid being drawn into the device by placing a color indicator on the tip of the liquid dispensing device.
It is another object of this invention to provide a color tip that is not uniform such that it may improve the differentiation between the color coating, the container, and the tip of the liquid dispensing or extraction devices.
It is another object of this invention to provide an assembly that consists of a liquid dispensing or extraction devices with a color tip and a container marked with the same color so that the liquid dispensing or extraction devices and the container may be identified together.
a and 4b is a close up view of the pipette showing alternate embodiments of the pipette.
While describing the invention and its embodiments various terms will be used for the sake of clarity. These terms are intended to not only include the recited embodiments, but also all equivalents that perform substantially the same function, in substantially the same manner to achieve the same result.
As shown in
The coating 14 should be of a density to allow a view of the liquid drawn up in the pipette 12 through the supernatant 20.
As shown in
Lastly, the color on the coating 14 may also serve to identify the pipette 12 for a particular use. For example, it may be useful to have a pipette 12 with a color coating 14 of “red” to be only used with extraction tube 24 with the same color “red”.
