Get more out of your pipettes!

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UncleBenBen

Well-known member
Supporting Member
Joined
Sep 2, 2015
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Location
Nashville, TN
No lab, whether for refining, medical, research or what have you, would be complete without these handy little gadgets...
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So I wanted to share a way to prepare them to get the most out of them. First, warm the tip of a pipette by holding it in your hand. If it is too cold, it will just break.

Next, grip about 3/16" with a pair of flat nosed pliers...
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Then pull in one fluid motion to stretch the pipette about 1/2". Once you stop pulling, don't try to pull more or it will break.
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Next, snip off the very tip...
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Don't worry about getting a clean cut. I use an old pair of tin snips that leave a rougher tip with tiny 'whiskers' of plastic that are actually beneficial. More on that in a moment.

With this finer capillary of a tip you create, comes much more control while transferring solutions without disturbing near as much fine sediments. You will get more uniform drops, and its great for use with the spot plate. Random drips and dribbles are greatly reduced if not eliminated.

The neatest use I've found so far is getting that last bit of solution off of particularly fine sediment or precipitate. This is where the 'whiskers' I mention come in. The tip of a prepped pipette will be rather flat. Put the flat side of the tip flat against the inside of the beaker down where the surface tension causes the solution to curve where it meets the glass. Just touch the solution with the tip and the 'whiskers' will help drag some of the liquid up as you move the tip, still flat against the glass, higher than the surface.

Now with a steadied hand, you can slowly release the suction bulb, and draw off the last bit from above the surface of the solution. If very careful, there will be but just the slightest disturbance of sediments, if any at all.

Y'all give it a try, I think you will like it!
 
Nice tip Ben! It reminds me of heating glass tubing and drawing it out to create small diameters. I'll have to give it a try. Now, where did I put my pipettes when we moved? :roll: :cry:
 
Handy tip!

Used to have to pull glass capillary for checking flash chromatography fractions via thin layer. You go through a lot of it! Made my own plates too :)
 
Thanks Lou and Dave. Though I'd like to take credit, this one comes from my high school chemistry teacher who swore by it.

He claimed that no matter who prepped the pipette, or how it was pulled, that the drops would be so uniform that X number of drops would always equal 1ml. Don't remember the number though.

Of course I had to call BS, seemed like too many variables to me. So he gave the class 3ml graduated test tubes and we tested. Sure enough it was spot on.
 
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