cleaning pipettes

[Andrew O'Neill]

I use plastic ones ever since I broke my glass pipette. I managed to keep the glass pipette clean and stain-free by rinsing it thoroughly after each use. Maybe I didn't have it long enough for it to get dirty...

[Kirk Gittings]

Incidentally, as a matter of good practice you should be using a pipette bulb, which makes the rinsing almost trivial.

I use this. Is that what you are referring to?

[Michael Cienfuegos]

I use this. Is that what you are referring to?

A pipette pump? That's what I use. I have one for my 5mL Pipettes and a red one (larger) for my 25mL pipettes.

m

[Harold_4074]

That's the contemporary, high-end equivalen.

The original pipette bulbs were probably just like a turkey baster bulb, but by the time I came along they were equipped with squeeze valves so that you can (with one hand and a bit of skill) fill, adjust, and empty the pipette with good control. What you have is probably better. There's a picture of a rubber "pipette filler" here: http://www.crscientific.com/pipettes.html

The real point of my comment was that mouth pipetting is really not a good practice. Folks did it for years, and some of them almost certainly regretted it. Usually a wad of sterile cotton would be placed in the top end, on the principle that if the solution wet it, the flow rate would be reduced enougn to protect the user (sort of).

[Kirk Gittings]

Thanks Harold.

[NancyP]

D'oh. Chromic acid. Shows you how long it has been since I have used glass pipettes (late 1980s).

[NancyP]

Re: the green pipette pump above. Our safety officer more or less banned these once people started using the flimsier disposable borosilicate glass pipettes. People would jam the pipette into the pump too vigorously, and the glass pipette would shear off and people would jam it into their wrist. I stopped using them when I had a near-miss with a Pasteur pipet (flimsy in the extreme). I prefer the old fashioned rubber bulb with valve if I am not using one of the fancy electric pumps.

[Cor]

Dedicated pipettes is indeed the way to go (I use disposable ones, and I removed the cotton on top so I can rinse with a spray bottle filled with distilled water). I now use this:



Well actually it's predecessor the nice ones above got replaced with, ( and I happily could recycle them....) no speed control but a joy for pipetting really viscous stuff like Mytol. We used to have the green ones Kirk posted in the lab, but they proven to be much less reliable and sturdy as the old fashion red balloon:



Best,

Cor

[Stoogley]

How about using pipe cleaners? (ala for tobacco pipes)

[Nathan Potter]

In the semiconductor industry the lab guys would use piranha etch as a glass cleaner. It does not etch glass but viciously attacks organic residue and most chemical stains. It's half sulfuric acid mixed slowly with half hydrogen peroxide by volumes. A short soak is all that is needed. The common sequence follows.

Piranha etch 2 to 5 min.
DI wash 3 min.
Ethanol rinse 1 min.
N2 blow dry maybe 30 sec.

All analytical reagents.

No doubt overkill for what you need.

Nate Potter, Austin TX.