how to fill the pipette solution

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zang
zang's picture
how to fill the pipette solution

Sorry for asking this kind of question.

I used a fine injection needle to fill the pipette solution into the pipette. But there must be better ways. For the poor patch clampers, what is  the easiest way to fill the pipette solution into the pipette?

Thanks.

The FFM
The FFM's picture
 I use these microfil tips

 I use these microfil tips http://store.wpiinc.com/Standard-Sizes_c_140.html  with 0.22 µm filter between the syringe and the microfil tip.  It works pretty well.  Rarely get a bubble with my patch pipette design and if I do it usually pops out with a gentle flick.

Alternatively you can pull your own really fine one using a vertical puller and 10 µl Drummond microdispenser glass.  just heat up the glass and pull vertically down fast when its hot enough.  you get a super fine tip that you can cut open with a sterile blade at the point that you want, which will fit right into the inside of the tip of your patch or two electrode voltage clamp pipettes.

The FFM
The FFM's picture
 of course the other trick is

 of course the other trick is to use the capillary action of the pipette glass to pull solution into the very tip of the electrode.

You'll need to use the glass that has an internal filament and after you pull the electrode place your tip with the open blunt end down into your internal pipette solution and it will draw up into the very tip of the electrode (takes ~2-5 min) and then back fill the rest of the solution as normal

pbm
pbm's picture
 Another approach that is

 Another approach that is very cost-effective is to pull 100 ul pipette tips over a small flame (I use a 22 ga blunt needle as a bunsen burner). It takes a little practice. I find the yellow tips (used to use Eppendorf tips, but yellow VWR or Fisher tips work) that are made of a hard plastic work best; the translucent or clear plastic tips don't work well. After you pull the tip, cut it with a razor blade, and use the original tip end of the pipette jammed into a 1cc tuberculin syringe to backfill the filler. You can pull fillers that are only a few hundred microns in diameter and several cm long very easily.

Advantages: very cheap (buy the tips by the bag), easy to replace (you can make a new one every day so that it is clean - no junk build up like those expensive "quickfills"), and flexible (in case you bend your pipettes).

Disadvantages: you have to practice to get the pulling right, and sometimes you might burn a finger if you are not careful. 

I learned this trick (and a bunch of others) a very long time ago, in the mid-80's, from another early adopter of the patch clamp method. 

andy123
andy123's picture
When you are using the

When you are using the pipette, you must not use your mouth to suck in the chemical you are working with. Sucking it through your mouth has a risk of the chemical accidentally going into your gut. Thus, always use your hand to fill the pipette.

handsomejohanna
handsomejohanna's picture
 

 
The pipette is filled by dipping the tip in the fluid, then drawing up the liquid by using a pipette filler to create a partial vacuum above the fluid. The surface of the fluid inside the pipette is generally concave and this is called the fluid meniscus.