Do not expect to find one micropipette to cover all your needs. Typically you will need a set of three or four pipettes. You will find one of the following numbers on most micropipettes:
2: useful to measure between 0.1 to 2 microliters
20: useful between 2 to 20 microliters
100: useful between 10 to 100 microliters
200: useful between 20 to 200 microliters
1,000: useful between 200 to 1,000 microliters
Once you found the right size of micropipette for your needs, now you need to find the right pipette tip. You can find them mostly in three sizes. Each size of tip is usually made to fit most of the micropipettes of a given size. It is always a good idea to check if the tips you are planning to order fit the micropipette you have.
This is the difficult part of the job. Accuracy is needed to deliver the right amount of the reagent. You may need practice to be precise.
To get the micropipette ready to obtain a liquid sample, first set the micropipette to the number of microliters you need. For this, each brand and model is different. Keep in mind that normally you can read one decimal point of the volume. Next, place a tip on the pipette, then depress the plunger softly until you feel it stop. You can press the plunger further down, but it will require extra pressure from your hand. Do not depress the plunger any further from the first stop you feel, or you will get a larger volume. Hold the micropipette at this position and now you are ready to draw up the liquid. Put the end of the micropipette tip in the liquid and let the plunger go up very slowly. If you let the plunger go too quickly, you will have drawn an inaccurate volume. Go extra slowly for viscous liquids such as glycerol and detergents.
Now that you have an accurate volume of the desired liquid in the tip of your micropipette, you can transfer it where you need by depressing the plunger. This time you will depress it further down than the first stop. Go all the way down and make sure all the liquid has left the tip. Make sure you change tips after each use.
Besides the general precautions you need to observe when using radioactive material, you also need to prevent contaminating your precious micropipette with radioactivity. It is advisable to use the more expensive filter tips. These are like your regular tips, but each tip has a filter that will trap any trace of aerosol that could reach your micropipette.
Most likely your work will involve the use of some reagents or enzymes stored at low temperatures. Make sure you do not immerse the tip too deep into the liquid. The cold liquid will cause the air in the tip to compress, and you will be suctioning liquid before you start to release the plunger.
Pipettes are also often employed in sterile conditions, so you want to keep your micropipettes clean and sterile. Do not sterilize your pipettes in the autoclave; you will ruin them. You can put the tips in the autoclave but not the micropipettes. Simply clean them with ethanol.
You can place your micropipettes and the tips under ultraviolet (UV) light. UV light destroys DNA. So, if there was any trace of DNA in your tips or micropipettes, it will not be amplified in the polymerase chain reaction (PCR).
Working with ribonucleic acid (RNA) requires the use a set of pipettes exclusively for RNA. You need to clean the pipettes with an alkaline solution and detergent.
Micropipettes require periodic calibration (every six to 12 months). Calibration should be performed by a qualified professional.