I recently purchased a few "button" data loggers for validating transport boxes and coolers. I have been playing around with one and it is quite simple to use and produce a graph of the temperature over time. I can set the logging rate as well as upper and lower temp limits which display across the graph as red lines so you can see at a glance if the temperature remained within range. I can also produce a time/temperature chart.

I assume these loggers should be checked out before use. Our laboratory support services department QCs all thermometers against a reference thermometer each year. They have never seen a temperature data logger and are not sure what to do since it does not have a display they can read alongside their reference thermomter. My suggestion is to set the data logger to record at 1 minute intervals and place it beside the reference thermometer at room temp, wait a few minutes, and record the temp off their reference and the time the reading was taken. Then place both in a refrigerator, wait for the reference thermometer to stabilize, and record temp and time again. I can then insert the data logger in the PC interface cable receptor, transfer the data to the PC, and look for the temperature it logged at the times the reference thermometer was read. I am not a QC guru but this seems to make sense to me. I know we have a lot of QC experts on this board so my question is....if you were to come inspect us, would you find this an acceptable method?

How expensive are these "buttons"?

Another question. Do the data loggers come with any kind of certification? We are thinking of using them in our coolers as a way of documenting temp. every 4 hours just like the charts on our refrigerators.

No, they do not come with a certificate which is why I want to check them against a reference thermometer.

I got them for $49 each. A $79 starter kit includes one button, one serial cable, and software.

You might also want to look at TempTale devices. I've used them for many years in doing validations.

http://www.sensitech.com/support/temptale/index.html

We use the product by BD (the SP100). They actually sell a calibration software for their unit, so the first thing I would check into is if the company that provides your buttons can do the same. If they don't, the procedure you have described is very close to how the BD system works. You basically plug the cable into the logger, and enter the temperature the reference device is displaying (after a 2 hour stabilization). This is only a single point calibration, but is the manufactureres method.

Only recommendations I can provide is to maybe wait longer than just a few minutes to make sure everything is stable, and try to avoid a "drafty' area to do this in (you especially don't want to have your PC fan blowing right on the area of either device when doing the room temperature check - when doing the cold check, use a lower drawer in the fridge, or just be sure the inside fan hasn't clicked in - this one can be tricky), second, double check that the loggers internal clock is syncronized with the clock that you are recording the reference devices reading time from (that way your comaprisions are of readings that are as close to the same time as possible).

Hope that helps.

They do not provide calibration software. I think I will use the platelet incubator for the RT reading. Waiting two hours to stabilize temp is a good idea. We have an old blood refrigerator we currently use for our "received, not yet in use" reagents. We are not in and out of it frequently like our blood storage refrigerators so this would be a good choice for us. I forgot to mention that the buttons internal clock would be synched with the PC clock. The PC is within 50 feet of both the platelet incubator and fridge so we would use the PC clock to record the time we read the reference thermometer.