Pipette like a pro - basics & tips for using micropipettes & serological pipettes

A pipette is a piece of lab equipment that you use to draw up and dispense liquid. They come in many sizes and types. The “classic” Pasteur pipette is basically as simple as pipettes get - glass tubes w/a narrowed tip - you attach a rubber bulb to the top & squeeze it to create suction to suck up liquid (people used to do this with their mouth - DON’T!) I don’t use Pasteur pipettes often because you can’t measure with them, but they’re good for adding liquid drop by drop, like when you’re trying to adjust the pH of a solution & have to add drops of acid or base until it settles on the pH you want. We also have plastic transfer pipettes ("eyedroppers”) that are similar to the Pasteur pipettes but they’re plastic and all-in-one (no bulb required)   
  
If I want to transfer volumes ranging from ~2mL-25mL, I use serological pipettes. These pipettes have measurement lines so you can move around measured volumes of liquid. You can use rubber bulbs (bigger ones) with serological pipettes, but (thankfully) we have electric “Pipet-Aids” to help. The top button draws up fluid and the bottom button releases it. The Pipet-Aid is powerful, so thankfully these serological pipettes have cotton plugs to prevent you from drawing up liquid too far and damaging the Pipet-Aid.  
  
For transferring volumes 1mL or less, we use micropipettes. These are probably our most-used pieces of equipment. They come in multiple volume ranges. When possible, you want to choose a range the volume you want is in the middle of, as that’s where it’s most accurate.  
  
We refer to these micropipettes in terms of the largest volume they can transfer - for example, a “P20” is a pipette which can transfer volumes from 2-20µL“P20” is a pipette which can transfer volumes from 2-20µL (a microliter (µL) is 1000X smaller than a mL). To use a micropipette, you push down the top button, place the pipette in liquid then release the button. Then move it to where you want it and push back down to dispense. Once you’re done, you push the ejection lever to eject the tip into a waste container (old salts containers work great - and I got really excited when, in the early days of my PhD work, we finally finished a good one…)   
  
Speaking of tips, different size micropipettes use different size tips. We buy them in “racks” that we refill our tip boxes with (so much more convenient than filling them one tip at a time like I did in undergrad). We also have filter tips that we use when we’re pipetting sensitive samples (like RNA) to prevent the pipette from dirty-ing the sample, or radioactive samples - to prevent the sample from dirty-ing the pipette. Pipetting the same volume over and over can be hard on the thumb, so we have a repeater pipette. It has different size tips and you can pull up more liquid than you need and have it eject a set amount every time you push down.   
  
So far, I’ve told you about single-channel micropipettes, but they also make multi-channel micropipettes that are thumb-savers when you have to pipette into multi-well plates. We have 8-channel and 12-channel ones in multiple volumes. 
 
more about lab equipment: http://bit.ly/equippedtoexperiment &    • Lab equipment: Tour, terminology, & t...    
 
more practical lab tips: https://bit.ly/lab_tricks_page 
 
more pipetting tips: https://bit.ly/pipetting_problems &    • Pipetting viscous liquids - reverse p...   &    • Random tips for choosing & using micr...   &    • Tips for when liquid jumps back & get...   &