Using a Volumetric Pipet

Proper use of a pipet is actually quite impactful on your research results. Many students use poor pipetting technique resulting in artificially high or low results that give large error.

Volumetric Pipets: These pipets have a specific volume that they will dispense when filled to the mark. When drawing a liquid into the pipet, place the end of the pipet at an angle on the bottom of your beaker or flask. If the pipet is completely vertical, you may cover the opening entirely and not be able to suction the liquid. Use a roller or pipet bulb to slowly pull the solution PAST the mark. That's right, you need to over-shoot the line. Once you have liquid past the mark, quickly remove the roller or bulb and place your finger over the opening on the end of the pipet. This will prevent liquid from escaping the pipet. Finally, bend down so the volumetric marking is at eye level and carefully twist the pipet back and forth while gently covering the open end with your finger. This will slowly release liquid from the pipet. Continue to twist the pipet until the bottom of the meniscus created by the liquid matches perfectly with the volumetric mark. Tighten your finger down to completely cover the opening on the end of the pipet and transfer it to your solution. Let your finger off of the opening and dispense the liquid into your flask or beaker making sure the end of the pipet remains in contact with the side of the beaker.

Now that's what I call a quantitative transfer!

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