The Pasteur pipette, also known as a dropper or eye droppers, is a laboratory liquid handling tool used to transfer small amounts of liquids.
Pasteur pipettes are traditionally made of glass, although today plastic Pasteur pipettes are common in laboratories around the world.
Pasteur pipettes are essentially glass or plastic tubes that are tapered to an opening point narrow at the lower end and are equipped with a plastic bulb or rubber on the upper end.
The combination of a pipette of pasteur glass and a rubber pear can also be known as 'pipette of nipple’.
What is the Pasteur pipette for?
The Pasteur pipette is designed to transfer small amounts of liquid from one container to another. Have a fixed volume of 10 ml.
Plastic Pasteur pipette
Plastic pipettes are they recommend when it is important to avoid the possibility of glass fragments, as in the case of embedded blocks, with the danger of damaging a knife of diamond.
Plastic Pasteur pipettes (or transfer pipettes) have their stems and bulbs in the form of a single plastic piece.
The laboratory pipette so general is used in biology, medicine and chemistry to carry out the carrying a measured volume of liquid, often as a dispensary of media.
It is a straight tube, which it can be made of plastic or glass, which has a narrowness at one of its ends and it is called a conical point. At the opposite end has a nozzle. These pipettes they are calibrated in small divisions, in this way it is possible measure different amounts of liquid in units that are between 0.1 and25 ml.
It is characterized by having a wide neck, a condition that makes it less accurate than the volumetric pipette. By for this reason, they are used when the accuracy does not necessarily have to be very high, at the time of taking a volume of solutions.
They are required especially when in laboratories it is necessary to transfer or measure the volume of a quantity of liquids from one container to another.
Types of pipettes
There are pipettes that lack great precision, that is why they are used for mostly to transfer liquids, on the contrary, there are others that are excessively precise and serve to measure the volume of liquid.
When it is necessary to transfer a determined volume of liquid, the volumetric pipette is used. Capacity of this type of pipette is between 1 and 100 ml. They are characterized by their roller shape, they are very thin at the ends and in the center possess a protrusion of greater thickness.
They are usually used when the accuracy of the measure is decisive for some record.
This type of pipettes have the form conical at its end, they are straight tubes. Along the tube you can see hash marks that allow the measurement of various amounts of liquid with a pipette.
This type of pipette usually they can measure a volume between 0.1 mL. and 25 mL. Despite the ability that have to measure several amounts of liquid at the same time, it is questionable their accuracy due to the flaws they have in the diameter of the tube. In that sense, volumetric pipettes are ahead of them.
Mohr and Serological Pipettes
Mohr and Serological Pipettes they are a subdivision of the measuring pipettes. The difference can be seen in the hash mark. On Mohr pipettes these markings culminate before the tip of the
pipette, meanwhile, in the Serological ones, they continue to the tips.
Among the serological pipettes also there are the blowing ones. This type of pipette has an opening in the top resembling a straw. This is so that the laboratory hold the top with your thumb and thus create the vacuum and seal the liquid from in the pipette.
Another advantage of the blowing pipettes is that they allow blowing at the end where the opening, to conduct the last bits of liquid that might be left in the receiving vessel, which increases the accuracy.
One of the features highlights of the blown pipettes is that they are evidently marked with a frosted band, or two thin rings, around the neck.
The color condition of the manufacturer should not be confused with the markings that the blowing pipette may have. Although it is possible to use the blow pipettes as mentioned, it could be dangerous to carry it out with a pipette whose marking is not clear enough as it happens with the blow pipette.
Pasteur pipette care
Pasteur pipettes are traditionally one of the most abused glassware items e misunderstood in the students' laboratories. The objective of this section is to teach you how to properly handle Pasteur pipettes.
Disposal and reuse of pipettes
The glass in a Pasteur pipette costs only 5 cents. So why not use it and throw it in the trash? First of all, it is always better to reuse something if possible, to help preserve our resources and the environment. Why have someone make another one if the one you have is perfectly fine, just a little dirty? Why add garbage to landfills if it is avoidable?
Secondly, "dirty" glassware in a chemistry laboratory is not only "dirty", but also a hazardous waste. The "dirt" in it is a chemical, and almost certainly a dangerous chemical.
Legally and morally it is not they can place hazardous waste in the city landfill, which is where finish the contents of the trash can.
To avoid this, you need to clean and reuse your Pasteur pipettes whenever possible. Do it immediately, before that the chemical dries out in the pipette and it is impossible to clean.
If the pipette has only been used for a solvent (pure hexanes, ether, ethanol, etc.), just leave it dry.
If it has been used for a solution of a solid compound in a solvent, or for an aqueous acid or a base, rinse it with the minimum amount needed to remove most of the of the chemical - use water or acetone - in the waste container appropriate, and then rinse it thoroughly under running water.
Put it in the drawer of your lab and will be ready to use at your next lab meeting.
If the above steps do not clean it, or if it is broken, place the Pasteur pipette in the broken glassware hazardous waste container.
Suitable pipetting technique
Pasteur pipettes should be used in a vertical or almost vertical position. The light bulb goes up, the pipette tip points down.
Never hold a full pipette upside down or horizontally. If you hold it like this, the liquid enters the light bulb, which means:
The bulb is dirty and should not be re- used, which means that 39 are wasted centavos.Si it is dirty but left in use, it will discolor quickly, it will crack, dry out and simply arruinará.Si a dirty light bulb is used again, any chemicals left in it from previous use will be mixed with the new solvent, contaminating the new disolvente.Si a poorly used light bulb is saturated with solvent and it is left lying around, another student could pick it up without suspecting that it is a glove, and receive a hazardous chemical in all of its manos.Si even a clean light bulb comes into contact with any solvent, the solvent will leach the compounds present from naturally in the rubber bulb, which will contaminate its solvent and, by therefore, your reaction.
The basic parts of a pipette be:
Push button, large adjustment button volume, tip eject button, volume indicator, tip eject button, tips, shaft, disposable tip.
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