Little Asia – Rotavap incident

On popular demand, continuation of my “Little Asia” series (all the publishers wishing to acquire rights for screening purposes are welcome to contact me).

Few weeks ago our department was suffering from dry ice shortage. For three days we were forced to use normal ice and tap water for cooling. That includes rotary evaporators, usually filled with dry ice/acetone.

For those unaware – rotary evaporators are used for removing excess of solvent (water or more likely organic solvents). Most of the rotavaps are cooled using water, but water cooling isn’t really enough to condense low boiling solvents, like DCM or diethyl ether under reduced pressure. That’s why in our lab we’re using cold traps (see picture) filled with cooling mixure. Usually it’s acetone/dry ice, which has a constant temperature of -78°C, or water/ice mixture (0°C).

So for three days cold traps were filled with water/ice. It’s quite obvious that before filling them with with dry ice you have to empty them first, or at least it’s obvious to everyone who has even a little reason.

On the glorious day when our department was finally supplied with dry ice I’ve spotted L. happily filling the cold trap. Perturbed with a vague premonition of danger I’ve asked him what he’s doing.

- Have you emptied the water first?

- What?

- There was water in the trap, have you emptied it first?

- I didn’t know water there.

- There was no dry ice for three day – so we were using water/ice. And there is a post-it note on it saying “water/ice”

- Oh.

- You have to empty it otherwise freezing water will crack the condenser.

- Yes, yes. (Standing there and staring at me with a blank expression on his face)

- You have to do it NOW!

- Yes, yes (Still standing there)

- So why aren’t you doing it? (Lost my nerves – took out the freezing cold trap and  showed it to his hands) You have to do it now and don’t put the dry ice from it in the sink or it will crack the pipes.

Another blank expression – so I took a large beaker from the cupboard and put it in front of him. He turned the trap upside down – but the water already froze. I just told him that he had to get it out and I didn’t really care how and I left. Suppose he managed to get it all out cause the trap survived. Which is pity in a way, because we’d have one more excuse to get rid of him. Really, he’s supposed to be a PhD student, I always assumed that you have to be at least a little bit smart to do that. Obviously I was wrong…