If you need to measure how much liquid is in a tube (small volumes) you can do this with a micropipette. Start by estimating how much there is based on how much should be in there or what the approximate volume lines on the tube show). Then set the volume of an appropriate size micropipet to slightly less than that amount. Spin down the tube briefly to collect all the liquid in the bottom of the tube, then aspirate (suck up) the liquid. There should be a little excess liquid in the tube still. So, with your pipet tip still in there, start turning the dial on the pipet until you have the last of the liquid sucked up without sucking up any air (you want the liquid to be right at the bottom inside of the tip). Now read out the volume the pipet is set to. That’s how much liquid is in the tube.

If you overshoot it or overpull it and end up sucking up some air, just turn the dial to the right slowly, releasing that excess air (I like to do this with the tip against the bottom of the tube so that if any liquid comes out I can easily suck it back up without bubbles).

Be sure that when you’re turning the dial you don’t end up going beyond the pipet’s range (e.g. don’t go above 200 with a P200 - if you see there’s more than 200, use a P1000).

more practical lab tips: https://bit.ly/lab_tricks_page  &    • Practical lab tips & tricks  

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