Multichannel pipettes, while intimidating, are no different than any other pipette. It has a plunger by which you take a sample, and transfer it somewhere else.
These pipettes are used for running reactions on plates, typically.
A plate is a piece of .. well .. plastic, in which there are wells (96 wells is typical) where you can put samples and run tests.
Now, think about this: Would you rather pipette something 96 times, or use a tool designed to do 12 wells at once? Thought so.
Here enters the multichannel pipette. The designs vary, but are essentially the same. There are multichannel pipettes that are electric or manual, and have a variety of different dispensers. Some pipette tips will not fit other models, and some models are built traditionally, or have a more ergonomic feel.
Here's what you need to watch out for
- Lighting. Poor lighting, or not being able to see clearly, will likely result in cross contamination. Make sure you can see what you're doing.
- Check your pipette tips before and after testing something. Even today, I had to throw out an entire box of tips. Every single tip in the box, I kid you not, was completely bent/destroyed. Age? Shock from autoclaving? Who knows. Those tips were trash, and I would have failed my tests if I didn't check the tips before using them.
- In my experience, I've seen that the data resulting from the middle wells (wells 4-8) have the lowest CV's, where the end wells (1-3 and 9-12) have the highest CV's. Arrange your samples so that the most important samples are in the 4-8 range.
- Consistency. No matter what you do, your results will not be superb unless you follow the same tiny quirks every time. Did you wait for the samples to reach room temperature? Have the samples been vortexed? Are the pipette tips cleared before I move to the next set of wells? These are all things you should be thinking about while using a multichannel.
- The plate itself. Plates are designed to be used in conjunction with plate readers. Plate readers measure the absorbance of many sample by sending a certain frequency of light through the bottom of wells. However, if you touch the bottom of the plate with anything (and I do mean, anything) you run a very high risk of adding interference to the readings.
- Just to say it again, do not touch the bottom of the plate with your glove/hand. You will mess up your readings.
- Plates, and multichannel pipettes, by their character, are designed to handle a very small amount of sample. That's all fine and dandy. But, remember, small sample amounts lead to higher error. You need to be careful with your technique. If adding A to B, make sure to prewet your pipette tips with A and then, after transferring A to B, thoroughly mix A and B together using a circular motion and cycling the wells multiple times using the same tips. Cycling means to pull the A+B mix up, dispense it, pull it up again, and keep repeating until you feel confident that the wells are mixed.
- Every multichannel pipette is different and has its quirks. Ideally, any pipette you use should be calibrated (indeed, in a regulatory setting, all pipettes you use will be calibrated by a professional). You should notice that the image I showed above has a sticker on it. This marks that the pipette has been calibrated. Learn to use your pipette, because no multi-channel pipette is perfect or similar to another.
Obligatory yer a wizard 'arry:
Yes. Multichannel pipettes are just like wands. Some just won't work for you.
Remember: Multichannel pipettes are just like any other pipette. Remember to make sure your pipette tips are secure, and that you pull your sample in a consistent manner.
That's all for now; stay focused for next time.