Editing Pipette (section)

==Common pipettes==
=== Air displacement micropipettes ===
{{main|Air displacement pipette}}

Air displacement micropipettes are a type of adjustable micropipette that deliver a measured volume of liquid; depending on size, it could be between about 0.1&nbsp;[[Microlitre|μL]] to 1,000&nbsp;μL (1&nbsp;mL). These pipettes require disposable tips that come in contact with the fluid.

These pipettes operate by [[piston]]-driven air displacement. A vacuum is generated by the vertical travel of a metal or ceramic piston within an airtight sleeve. As the piston moves upward, driven by the depression of the plunger, a vacuum is created in the space left vacant by the piston. The liquid around the tip moves into this vacuum (along with the air in the tip) and can then be transported and released as necessary. These pipettes are capable of being very precise and accurate. However, since they rely on air displacement, they are subject to inaccuracies caused by the changing environment, particularly temperature and user technique. For these reasons, this equipment must be carefully maintained and calibrated, and users must be trained to exercise correct and consistent technique.

The first verified adjustable air displacement micropipette was invented by [[Joseph Lister]] during or prior to 1877 (see [[Pipette#History|History]] section above).<ref name="e841"></ref> The modern micropipette was patented in 1960 by Dr. [[Heinrich Schnitger]] in [[Marburg]], Germany. Afterwards, the co-founder of the biotechnology company [[Eppendorf (company)|Eppendorf]], Dr. Heinrich Netheler, inherited the rights and initiated the global and general use of micropipettes in labs. In 1972, the modern adjustable micropipette was invented at the University of Wisconsin-Madison by several people, primarily Warren Gilson and Henry Lardy.<ref>{{Citation|last=Zinnen|first=Tom|title=The Micropipette Story|date=June 2004|url=http://www.biotech.wisc.edu/outreach/pipettestory.html|access-date = November 12, 2011}}</ref>

Types of air displacement pipettes include:
* adjustable or fixed
* volume handled
* Single-channel, multi-channel or repeater
* conical tips or cylindrical tips
* standard or locking
* manual or electronic
* manufacturer

Irrespective of brand or expense of pipette, every micropipette manufacturer recommends checking the calibration at least every six months, if used regularly. Companies in the drug or food industries are required to calibrate their pipettes quarterly (every three months). Schools which are conducting [[chemistry]] classes can have this process annually. Those studying forensics and research where a great deal of testing is commonplace will perform monthly calibrations.
{{gallery
|File:Single channel rack.jpg
 |Single-Channel Pipettes designed to handle 1–5&nbsp;ml and 100–1000&nbsp;μL with locking system
|File:P5000 pipette.jpg
 |A 5,000&nbsp;μL (5&nbsp;mL) pipette, with the volume to be transferred indicated. 500 means that the amount transferred is 5,000&nbsp;μL.
|File:P1000 pipette.jpg
 |A 1,000&nbsp;μL (1&nbsp;mL) pipette, with the volume to be transferred indicated.
|File:Pipette tips-different 1.jpg
 |A variety of pipette tips.
}}

==== Electronic pipette ====
{{main|Electronic pipettes}}
To minimize the possible development of [[musculoskeletal disorders]] due to repetitive pipetting, [[electronic pipettes]] commonly replace the mechanical version.
[[File:Air-displacement electronic pipette with maximim volume of 10mL.jpeg|thumb|left|195x195px|Single-Channel [[Electronic pipettes|Electronic Pipettes]] designed to handle 0.5–10ml]]
[[File:VIAFLO-electronic-pipettes.jpg|alt=VIAFLO electronic multichannel pipettes from INTEGRA Biosciences|thumb|VIAFLO electronic multichannel pipettes from INTEGRA Biosciences|none]]
{{Clear}}

===Positive displacement pipette===
{{main|Positive displacement pipette}}
These are similar to air displacement pipettes, but are less commonly used and are used to avoid contamination and for volatile or viscous substances at small volumes, such as [[DNA]]. The major difference is that the disposable tip is a microsyringe (plastic), composed of a capillary and a piston (movable inner part) which directly displaces the liquid.
<gallery>
File:Positive displacement pipette.jpg|Positive displacement pipette
File:Pos pipette showing grappler.jpg|The [[Chuck (engineering)|chuck]] which will be used to move the plunger
File:early pipette.jpg|An early pipette
</gallery>

[[Image:Vollpipetten.jpg|thumb|upright=0.25|Several sizes of volumetric pipette.]]
===Volumetric pipettes===
{{main|Volumetric pipettes}}
'''[[Volumetric pipettes]]''' or '''[[bulb pipette]]''' allow the user to measure a volume of solution extremely precisely (precision of four significant figures). These pipettes have a large bulb with a long narrow portion above with a single graduation mark  as it is calibrated for a single volume (like a [[volumetric flask]]). Typical volumes are 20, 50, and 100 mL. Volumetric pipettes are commonly used to make laboratory solutions from a base stock as well as prepare solutions for [[titration]].

=== Graduated pipettes ===
{{main|Graduated pipette}}
[[Graduated pipette]]s are a type of macropipette consisting of a long tube with a series of graduations, as on a [[graduated cylinder]] or [[burette]], to indicate different calibrated volumes. They also require a source of vacuum; in the early days of chemistry and biology, the mouth was used. The safety regulations included the statement: "Never pipette by mouth KCN, NH3, strong acids, bases and mercury salts".  Some pipettes were manufactured with two bubbles between the mouth piece and the solution level line, to protect the chemist from accidental swallowing of the solution.
{{gallery
|File:"Pfc. Johnnie Mae Welton, Negro WAC, laboratory technician trainee, conducts an experiment in the serology laboratory sf - NARA - 531360.tif
 |A person pipetting by mouth, now considered an unsafe practice
|File:2Pipettierhilfen.jpg
 |A manual propipetter adjusted by turning the wheel with the thumb
|File:Pipetteerballon.png
 |A manual propipetter adjusted by squeezing the valves marked E and S
|File:Pipettier-Hilfe.jpg
 |An automatic propipetter adjusted by pressing the button and toggling the switch
|File:Motorized pipetter blue.jpg
 |An automatic propipetter adjusted by pulling and releasing the triggers
}}

[[File:Pasteur Pipets.jpg|150px|thumb|right|Pasteur pipettes with rubber bulbs attached.]]
===Pasteur pipette===
'''[[Pasteur pipette]]s''' are plastic or glass pipettes used to transfer small amounts of liquids, but are not graduated or calibrated for any particular volume.  The bulb is separate from the pipette body.  Pasteur pipettes are also called '''[[teat]] pipettes''', '''droppers''', '''eye droppers''' and '''chemical droppers'''.

===Transfer pipettes===
[[File:Plastic Pasteur pipette.jpg|thumb|left|A transfer pipette]]
'''[[Transfer pipette]]s''', also known as '''Beral pipettes''', are similar to Pasteur pipettes but are made from a single piece of plastic and their bulb can serve as the liquid-holding chamber.