Handling and Selecting Micropipettes in Laboratory

Handling Micropipettes

• Micropipettes are precision instruments that are expensive (about $200 each) and easily broken, but good technique can make them last without repairs.
• Store micropipettes upright on a rack when not in use.
• Use smooth action when handling micropipettes, avoiding snapping noises.

Selecting the Correct Micropipettor

• Select the correct micropipettor for the job by checking the size range on the barrel.

Preparing to Use a Micropipette

• Choose the correct micropipette and set it to the desired volume.
• Do not exceed the micropipette's volume range, as this can break it.
• Always put a tip on the pipette, using a different size tip for each size pipette.

Scales on Micropipettes

• White top micropipettes have a scale of 0.5-10 μL, with markings at 1 μL, 10 μL, and 100 μL.
• Yellow top micropipettes have a scale of 10-100 μL, with two scales: one from 10 μL to 0 μL and one from 10 to 0.
• Blue top micropipettes have a scale of 100-1000 μL, with markings at 100 μL, 200 μL, ..., 1000 μL.

Using a Micropipette

• To draw up a sample, depress the micropipette to the first stop, immerse the tip in the liquid, release slowly, and the liquid will be drawn into the tip.
• Withdraw the tip by pulling the pipette straight out.
• To deliver the sample, insert the tip into a container, depress the push-button to the first stop, pause for 1 second, then depress to the second stop and pause again for 1 second.

Fine Points on the Process

• Prewet the tip by aspirating and expelling the liquid three times for accurate delivery of the desired volume.
• Immerse the tip about 2-6 mm below the top of the liquid, avoiding the sides and bottom of the container.
• Use a fresh tip for every sample of a different composition.