Question 1

What are the main components of a micropipettor?

Accepted Answer

A micropipettor has several key components: the plunger at the top for drawing up or expelling liquid, a volume adjustment dial to set the desired volume, a volume readout display showing the measurement, disposable tips loaded at the bottom, and a tip eject button with shaft for removing tips. These components work together to enable precise microvolume transfers.

Question 2

How does a micropipettor draw liquid into the tip?

Accepted Answer

A micropipettor works by air displacement. When you depress the plunger halfway to the first stop, it displaces air from the pipette tip. As you release the plunger back to rest position, a vacuum forms, drawing the liquid into the tip. Wait one second after releasing to allow the liquid to fully enter before removing the pipette from the sample.

Question 3

What volume ranges do different micropipettor sizes handle?

Accepted Answer

Micropipettors come in various sizes with different volume ranges. The P-2 transfers 0.2-2 microliters, the P-1000 delivers 200-1000 microliters, and the extended family includes models like the P-5000 that transfers up to 5000 microliters. Each micropipettor is color-coded and numbered for easy identification of its specific volume range.

Question 4

How should you hold and position a micropipettor during liquid transfer?

Accepted Answer

Hold the micropipettor upright with the narrow body in your palm and the overhang over your index finger. When aspirating, immerse the tip 1-3 millimeters into the sample. When dispensing into a vessel, hold the micropipettor at a 10-45 degree angle against the inside wall to prevent bubble formation. This positioning ensures accurate and clean liquid transfers.

Question 5

What are common laboratory applications for micropipettors?

Accepted Answer

Micropipettors are frequently used for transferring cell suspensions to culture plates for various experiments and loading samples for analytical techniques like DNA gel electrophoresis. They can also mechanically disrupt tissue to obtain single cell suspensions. Variants like repeater pipettes and multichannel pipettes extend their utility for serial pipetting and loading entire rows of 96-well plates.

Question 6

Why is choosing the correct micropipettor size important?

Accepted Answer

Selecting the appropriate micropipettor for your volume range is critical because using the wrong size can lead to inaccurate measurements and failed experiments. Each micropipettor is designed to work optimally within its specific volume range. Correct choice ensures precise liquid transfer and reliable experimental results.

Question 7

What maintenance practices keep micropipettors in good working condition?

Accepted Answer

Always store micropipettors upright when not in use to preserve the internal volume adjustment mechanism. Never turn the volume dial above or below the instrument's specific range, as this can damage the mechanism. Change tips after each volume transfer to avoid cross-contamination between samples. Maintain smooth, consistent plunger pressure for optimal performance.

Introduction à la micropipette - Quiz d'évaluation