Would warming of serum to -15 to -10 C alter our anaysis of protein and small molecule metabolites
Question: One of the compressors on our -80 degree C freezer went out last night and the temperature climbed to -15 to -10 degrees C over a 12-14 hour period of time. We had importatn serum samples stored in this freezer and we have now transerred them to another -80 C freezer. However, we are wondering if warming of serum to -15 to -10 C would alter our anaysis of protein and small molecule metabolites. Do you have any information that might shed some light on this question?
Answer: We are sorry to hear about your equipment failure. There are two issues: (1) potential damage to your sample and (2) preventing future problems of this nature.
Warming the sample above the eutectic temperature (in this case ~-26 C), you will subject the proteins in your serum to high salt concentrations and interactions with the ice phase. Both of which can be damaging. It is highly likely that this warming has caused irreversible denaturation and aggregations of serum proteins. Small metabolites 'may' be ok.
Secondly, there are many, many investigator who store samples in their laboratory where the samples cannot be continuously monitored. In order to prevent future problems, we would strongly suggest that you install a monitoring system that permits someone to be notified in the case of an equipment failure. If you have access to a biorespository on your campus, you may also consider using this facility. Most repositories have monitoring systems and routine maintenance protocols to reduce/prevent failure of critical equipment.
