Thursday, December 29, 2011

60 mL syringes can get unstable

The syringe, after the incident. Credit: UCLA/The Safety Zone
One of the details that keeps coming back from the Sheri Sangji case was the use of a large plastic syringe to perform the transfer. They're quite difficult to handle, as commenters can tell you:

Scale-up + nasty reagents + enthusiasm + work done in hurry + poor technique is how typically lab accidents happen. I think a limited previous research experience is more dangerous than having no experience: it lends false self-confidence. (I had many close calls in the lab, often working alone) 
In retrospect, someone should have looked over Ms. Sangji and warn her that giant syringes are terrible for air-free work and that a much better choice is using a graduated addition funnel with a septa and a canula transfer under positive pressure.
Anon122820111028p adds:
I, too, use plastics with Li reagents...but these plastics we are using have a luer lock... Unfortunately, those giant 60 mL syringes 1) are not luer lock, and 2) effing difficult to control the plunger. I HATE using them. Cannula is the way to go if you are going to transfer that much of a reagent.
I've been wanting to illustrate the problem with large syringe instability for quite some time; that the Sangji case is back in the news is a good time to bring it up. I took a NEW syringe home, pulled the syringe past the ridge that keeps the plunger in (which we've all done to get a little more into the syringe, although hopefully not with pyrophorics) and asked a young child that I know to tap the plunger. You can see the results below:



For large transfers of liquid in the lab, you're much, much, much better off using a cannula transfer. Young chemists (and old!), learn the lesson of Sheri Sangji and take note. 

8 comments:

  1. I always loved doing cannula transfer. Sure it was more dishes to do afterwards, but it was always satisfying to watch materials dissapear "on their own".

    ReplyDelete
  2. I'm with you. I love plastic syringes (we have luer lock ones as well). But I make it a habit never to use more than a 20 mL syringe for organolithiums (for t-buli i only use 5-10 mL ones at most). And yeah delivering reagents with a 60 mL is a pain in the ass. The only good use I've found for a syringe that size is as a very large grease gun!

    ReplyDelete
  3. We used to have luer lock syringes in my old job, after a couple of blocked syringe incidents, causing the needle-barrel separation. Where I am now, we don't stock them. I think they would if it were not for the price though - slip and lock syringes are identical in function (until there is a problem) but quite different in price. So you can get along quite well with slip syringes. As long as you are careful about the limitations of the connection.

    ReplyDelete
  4. "and asked a young child that I know to tap the plunger."

    I assume said young child was wearing appropriate PPE?

    ReplyDelete
  5. I have also experienced failure with those plastic 60 mL syringes and not just pulling the plunger out the back. With repeated uses the seal will go and sometimes with fewer than 4 uses in short succession (which I luckily experienced when pulling 200 mL or so from a solvent still). When that happens the user can get a spray of solvent when they push the plunger down hard.

    ReplyDelete
  6. if you absolutely must use oversized syringes, for example in a syringe pump addition, buy Hamilton air-tight Luer lock glass syringes with a Teflon-tipped plunger. (The plunger should never be placed into drying oven and the glass body should be heated only to temperatures below 100C, preferably under highvac)

    ReplyDelete
  7. Yes, the Hamilton Gas Tight Luer Lock syringes have very sturdy plungers that don't slip and they syringes don't degrade. Even for small quantities, I found these much easier to handle than the disposables. Before we got those Hamiltons, I would hold the needle to the barrel manually because I had had enough of separating syringes and reagents spraying everywhere while under an Ar balloon.

    ReplyDelete
  8. Hamilton air-tight Luer lock glass syringes are much more expensive than the plastic disposables. Does anyone know if a stretched research budget contributed to the accident?

    I know when I was in grad school (not at a UC) I did some things that I was terribly uncomfortable with because I knew that it was the cheap (not safe) way to do things. The research group was managed through fear and several students had accidents. At least one student hid an accident from the professor out of fear of delaying his long path to graduation.

    ReplyDelete