Thursday, September 27, 2007
I have a lot of NMR tubes and as a result I don't clean them very often and when I eventually decide to do something about it I'm faced with something like 30 dirty tubes. Now firstly if you work this way you have to soak the NMR tubes as soon as you are done with them. If you just let them evaporate to dryness you are in trouble. I normally just empty the tube and fill it to the lip with acetone and cap it. This way it wont dry out for months.
When I was cleaning my tubes the other day I had three synthetic organic chemists from three different countries walk up to me and ask what I was doing. This was somewhat surprising so I've decided to share with you what I thought was common knowledge: The NMR Tube Cleaner. These things are commercially available (expensive) or you can have your glass blower make one at a reasonable price. You can see my set up on the picture above. This is how it works:
(1) take the cap of your NMR tube and attach it to its base
(2) stick the tube in the cleaner (see picture) so that the cap seals the opening at the top
(3) squirt solvent(s) into the solvent opening (see picture).
The system is under vacuum and the solvent gets sucked through a thin tube that goes to the bottom of the NMR tube. It is very effective and I usually do a combination of solvents to get rid of everything. Its smart to have a three way tap between the cleaner and the pump so that you can let air into the cleaner without having to turn the vacuum off all the time. There's an NMR tube entry at Wikipedia that also describes the NMR tube cleaner. D!
Friday, September 21, 2007
Yes I know! It's pretty quiet around here. My Internet connection at home is dead. I'm on the phone with my Internet provider every day to resolve this issue but it is a slow process.....So I guess a bit of blogging from work is required (Sorry boss. I'll run that column in 15 minutes). I'm writing papers at the moment and this always brings up the issue of authors. Who's on and who's off? Over the years I've experienced some pretty disturbing things in this category:
(1) You send the paper off to your boss for proof reading etc. and it comes back with another name on the paper! Why? The boss feels bad about not giving that person credit for something completely unrelated and is trying to make up for it.
(2) People doing routine analysis go on all papers. This category is a bit of a grey area as some techniques may be routine to the person doing it but does require years and years of experience. An interesting issue in this category is X-ray crystallography. Many older scientists (50+ years) don't realise that this has become a routine operation and religiously put the x-ray dude on all papers. Granted in the world of small molecule X-rays the crystallographer should go on sometimes when things aren't trivial. However, 90% of the time this is definitely not the case.
(3) Everyone in the lab goes on all papers! This is really far out but nevertheless the policy in some labs. By everyone I also mean the technician making up the solutions.
(4) And then there are the totally reasonable, serious scientist that will actually ask to have their name removed from the paper as they don't think they have contributed enough. I like this person much more than the evil pseudo-scientist snake that will do anything to sneak their name on a paper.
There's much more where this is coming from. Another post on the topic coming up shortly. D!