Pipetting is a basic lab skill that we use every day. Knowing how to properly use a pipette is important for maximizing precision and minimizing contamination and protocol error. First, determine which pipette you need. Different pipettes work with different volumes. We need to dispense 100 microliters, so let's use this one that's labeled 20 to 200. Adjust the pipette so that the correct volume is showing - you don't want to accidentally transfer too much or too little. Next, install the correct tip on the end of the pipette. These are usually color coded, but in case they aren't, just be sure that the tip fits perfectly. Before lowering the pipette tip into the liquid, press down on the plunger on the end of the pipette. Stop when you feel resistance. Lower the pipette tip into your stock container. Try to keep the tip just below the surface of the liquid so that excess liquid doesn't coat the sides of the pipette tip. Raise up on the plunger so that the liquid enters the pipette tip. Make sure the tip never comes above the surface of the liquid or you'll get bubbles in the tip and dispense an incorrect volume. Now grab the container you're dispensing into. Hold it at a 45 degree angle and keep the pipette vertical. Dispense the liquid against the side of the container. This time when you feel the resistance, keep pressing. This will ensure that all the liquid leaves the pipette tip. Try not to cause bubbles while dispensing the liquid. When you have depressed the plunger all the way, raise the tip out of the liquid before releasing the plunger. Inaccurate transfer volumes can be caused by many issues. Leaky or poorly sealed pipette tips are a common factor. Reusing tips is known to reduce accuracy, and failing to dispense against the wall of the container can cause drops to remain stuck to th To test the accuracy of your pipettes and your technique, try dispensing several 100 microliter drops of water onto your scale. Each one should be precisely 100 milligrams.