A couple of days ago I have seen a comment on twitter made by @Bam294 – here it goes:
Now, putting aside the fact that it is a wrong decision to transfer samples from -80 degrees to plus 4 degrees, it reminded me of the importance of order and documentation of freezers sample, especially those of the deep freezers.
A day after seeing this twit, I also happened to organize my glycerol stocks in the -80 deep freezer for the lab cleaning day happening next week. I would like to comment on some important points that I found crucial for well organized stocks:
- Monitor your glycerol stocks/samples – While this might sounds odd for those of you who routinely fetch vials from your deep freeze samples box, don’t forget that there are boxes that you have not opened for some time. Every couple of months check and see that nobody moved/opened or that the labeling is still there. You’d be surprise at the mess you can find when storing your samples in a communal storage location.
- Liquid nitrogen and peace of mind – I know, these two doesn’t seem to fit (unless you’re freezing sperm cells) but they do, actually. I had to rearrange my glycerol stock and I found it very comforting to have a box full of sizzling liquid nitrogen at my disposable to spill over my specimen from time to time while I was doing my rearrangements. Even though I was working at room temperature for almost fifteen minutes, none of my samples thawed by a bit. This is a great way to extend the time allocated for extensive documentation and reorganization of your samples. I have used this trick when I was logging all of my stuffs in the storage module of BioKM web-based laboratory management system.
- Long-term labeling – I must admit, I was sure I was using a smart labeling scheme. Before mixing the bugs with the glycerol and throwing them into the liquid nitrogen I was labeling my tubes by both writing on the top with a marker, then putting on the top a Toughspot from USA scientific and finally adding a regular label on the side of the tube which was also wrapt with a 3M tranluscent tape. Well, guess what? Both suck! Just imagine I was pulling out a tube with almost no marking on the top (the glue of the toughspot removed most of it), the toughspot sticker was strolling around the box, and the side labeling was sunken to the bottom of the well. At that point, if I had mistakenly toppled my box, I would have lost 2-yr worth of glycerol stocks! Yeah, that’s frickn bad! What have I learnt?
- First of all, I will not use Toughspots anymore! They are twice as expensive and they are worthless.
- From now on I am labeling my tubes with a permanent marker on both the top and the side of the tube. On the top I am writing the gene and bacteria strain and on the side the complete information including the date (super important!). I know that for some it might seem trivial, but I am sure many count on different types of labels which are easier to write on.
I must admit that I was lucky enough to have my box fully documented in BioKM so even If I have lost my labels, I can have the confidence that I know what was the content of that tube. I am currently exploring the option to duplicate some if not all my glycerol stocks so I can label them (due to the moisture of the tube’s surface, I can’t write or stick anything on the tubes).
So, visit your frozen sample from time to time, just to make sure all is the same as you froze them.