Arrgh pipet

September 22, 2006 3:27 PM

Biochem lab question: How do I clean the barrel of my pipettor?

I work at a biochem lab, and sometimes a bubble of human blood will travel up the disposable tip into the barrel. What kind of tool can I buy to clean up the gunk that accumulates?

posted by wuzandfuzz to Science & Nature (13 answers total)

You should just use filter tips; they have a barrier that prevents this; if you're using biohazards, you really should be using them already.
posted by metaculpa at 3:51 PM on September 22, 2006

Assuming you mean the sort that I think you do (looks like this, not like this?), you can pull off the metal ejecting-shaft thing-y and then unscrew the barrel and squirt 70% ethanol through ithe barrel to clean it. If it's really gunked up, you can soak it in 70% ethanol in a little beaker for a while.
posted by divka at 3:51 PM on September 22, 2006

Good question; what type is it?
Have you tried filtered pipette tips?
posted by strangelove at 3:52 PM on September 22, 2006

Some service contracts prohibit you from taking apart the pipettors.

Second the barrier tips.

If they're Gilsons or Raimis, just yank on the metal ejector and you can unscrew the round thing. Just remember where all the gaskets were originally. Don't lose any of the gaskets!

I usually wash in soap & warm water and soak in 10% bleach overnight, then rinse very well under running water the next day. Air dry, re-assemble (remembering where all the gaskets go).

Then again, there should be a user manual that should tell you exactly how to disassemble your particular pipettor.
posted by porpoise at 3:59 PM on September 22, 2006

get a block of styrofoam and cut a round hole in it, just large enough that you can stick one of those 50-mL falcon tubes into the hole with a little bit of resistance.

fill the tube partway with water, ethanol, acetone, ipa or your favorite solvent*. stand the pipet up in the tube with the tip in the solvent and float the whole deal on top of the water in a sonicating bath. sonicate for a few minutes, dump out the solvent, repeat until clean. let it air dry pointing down (you don't want to blow crud up into the barrel).

* make sure you don't use a solvent that eats the barrel of your pipet

also stop putting the thing down flat on the bench when there's stuff in it!
posted by sergeant sandwich at 4:05 PM on September 22, 2006

Some service contracts prohibit you from taking apart the pipettors.

yeah, and i think it's a good idea. its called a micropipet because it has (almost) microliter precision; taking it apart and monkeying with all the gaskets etc sounds to me like a damn fine way of introducing systematic errors in your volume measurements.

if that's no big deal for what you're doing, then go for it, but if your lab is anything like mine, you have only one or two of these pipets and they get used for everything.
posted by sergeant sandwich at 4:23 PM on September 22, 2006

There's also trained professionals you can call for problems like this. Sergeant sandwich makes a good point about accuracy- being off by even by a microliter can completey screw up results. Figuring out where a protocol went wrong is fun enough when your have accurate instruments; no reason to add another variable.
posted by jmd82 at 4:42 PM on September 22, 2006

Response by poster: hmmm... thanks for the suggestions. To clarify my situation, I run a lot of flow cytometry. Sometimes a little of the dried blood flakes off into the mouse tissue I'm staining, destroying my experiment. I am less worried about sterility and more worried about speed; is there a little brush or something I could be using to just scrape out the blood w/ soap and water? (VWR products preferred, my company is all about it)
posted by wuzandfuzz at 7:04 PM on September 22, 2006

Usually you can have a Rainin pipettor cleaned and recalibrated for about $30 or less. Given that they cost about $300 each new, it's a good deal. Ask someone who your local rep is, when they are on campus, or if there is a qualified cleaning service in-house (some buichem shops will have someone on staff who can clean them).
posted by caution live frogs at 7:06 PM on September 22, 2006

You could also learn to calibrate pipettes yourself. It's not hard.
posted by porpoise at 7:45 PM on September 22, 2006

I second Caution Live Frogs comment; if you are in Toronto I have a contact that will do repair and cal. work at your bench.
We use Co-op students for calibration...they are good for that...and buffers too!
Where is your flow cytometer (and pipette) from? Whomever it was manufactured or purchased from should be able to help you as well. I know that the Canadian VWR tech customer service is awesome, and your country's VWR may be able to help with your needs...plus the call centre girls often sound cute.
posted by strangelove at 6:08 AM on September 23, 2006

Third the filter pipet tips. They're great for radioactive or biohazard stuff and for pipettes like my p1000, which tends to do this to a wide range of solutions. My lab uses ART or Axygen filter tips, mostly, but other companies make them too. Additionally, if you use filter tips, you can delay cleaning and recalibrating your micropipette [although you should still have it done!], since the filter will prevent anything coming from the barrel of the micropipet from reaching the liquid you're pipetting.

Check with whoever in your lab handles purchasing first; there might be a pipette-servicing company that your lab always deals with. If not, check the posters around your institute or the yellow pages to find pipette calibrators/repairmen.
posted by ubersturm at 9:40 AM on September 23, 2006

First, how are you getting fluid inside the pipette? I use a variety of pipettes all day, every day at work and never have this happen. I've seen a first time user with a 5000 ul get that high of a splash back, but this should not be happening on a regular basis. Are you suddenly releasing the plunger at full speed? To pipette accurately, you should push to the first stop, lower the tip ~1/4" into the liquid (lower and the pressure from the liquid will force some up into the tip and cause you to pipette a larger amount), also keep the pipette vertical, holding it at an angle will also cause it to pull up too much. Then slowly release the plunger and wait a second before you pull the tip out. If the end of the tip is unfilled, you either pulled it out too soon or lifted it out too quickly (the acceleration can force some out the tip). Never leave a used tip on a pipette (moisture can evaporate and drift into the barrel) and if you are doing repeated measurements with the same tip, never lay the pipette on its side.
Rainin makes a pipette that you trigger to pull up the liquid and you can set the rate for the viscousity of the liquid.
If stuff has gotten up inside the pipette, it probably needs seals and a good cleaning. If you can find instructions for your pipette you can give it a cleaning yourself with some EtOH and kimwipes. VWR will come around and calibrate pipettes, but the people who do it are just salesmen and they don't clean or replace parts. You can send pipettes to www.pipettes.com for cleaning and calibration. If you have access to a balance that goes >1 mg you can check the calibration yourself. Tare a container (I use a weigh boat) and pipette in some distilled water. At room temp it should weight 0.998 mg / ul.
Oxford Benchmate pipettes (and maybe others) have a replaceble filter in the pipette itself, this way you don't have to get filter tips (pipettes.com had them 2 for $250 recently).
posted by 445supermag at 4:45 PM on September 23, 2006