Another great question from Kim Kinney at Clarian in Indy:
Clarian’s newest affiliate, Ball Memorial in Muncie, IN will be opening their new lab the first of December. We are purchasing small equipment and the subject of a water bath came up. At Clarian we have always used a 37ºC water bath to thaw our frozen coagulation samples and then mix well for 3-5 minutes on a mechanical rocker. Is a heat block adequate to use? I always thought that you need the water to completely surround and provide even temperature for thawing, but I could not find any documentation stating you should not use a heat block.
Hello, Kim, and thanks for the question. I know of no published data, but I am certain a water bath thaws specimens more rapidly and evenly than a heat block, simply because the contact with the tube wall is more consistent. If I were purchasing new equipment, I would probably order a few small circulating water baths. On the other hand, if I had heat blocks on hand, I would probably just use them rather than go to the expense of buying new water baths. I doubt there are any consequences for thawing a little more slowly, except for having to wait a minute or two longer. I’m curious to learn how others, especially folks at Esoterix, Machaon, Blood Center of Wisconsin, and Midwest do it, also the big guys at Quest, LabCorp, and ARUP.
I have never put specimens on a rocker, however, and am curious if you have found this improves their quality. Of course, when you take a specimen out of the water bath you can see the layers, and you must mix thoroughly by gentle inversion five or six times, but once mixed, the plasma components stay in solution/suspension. I wonder if too much time on the rocker could activate something. Again, I wonder how the big guys do it! Geo.