Best Practices for Biological Sample Storage and Management

Billions of biological samples are collected each year, but as Debra Lopez, Senior Director Supply Chain at ATCC, explains they often undergo a significant journey from their point of origin to their final consumption. Developing an effective and accurate approach to sample storage and management is therefore vital to ensuring your samples remain protected and traceable throughout this journey—reducing sample loss, minimizing risk of degradation, and saving time.

Storage

Once you have collected your samples, considering how best to preserve and store them is an immediate priority. “Sample storage is a complex activity,” states Lopez. Choosing the correct storage depends both on the recommended storage temperature of your specific sample and how long it is likely to be stored for. For short-term storage, refrigeration or lab freezer storage at -4˚F is ideal for biological samples, while long-term storage requires ultra-low temperature (-112˚F) or cryogenic storage.

Choosing the correct storage matrix is also important. Sample tubes or containers should be made of medical-grade resin as to ensure they will not crack due to extreme temperature, and the buffer should be carefully chosen to prevent pH change between ambient and frozen states, Lopez explains. The size of the storage vessel is also key. Using a tube that is too large for a sample “means that you are not only wasting precious storage space but also increasing the likelihood a sample will get damaged,” explains Amy Armstrong, Senior Product Manager of Automation Storage at Thermo Fisher Scientific. It is therefore vital that every storage decision is carefully considered, and nothing is left to chance.

Sample identification and labeling

In addition to correct storage, clear and organized sample labeling is critical for effective sample management. Proper labeling makes samples quicker and easier to find, and reduces the risk of damage and contamination from people mistakenly opening them. In addition to clearly identifying the contents, labels that contain unique number identifiers or 2D barcodes are the best approach—linking them to a database containing further details about the sample, its location, and its processing.

The labeling method is also important. If you choose to use physical labeling, care should be taken to ensure labels remain intact and readable at all times. Freezing conditions and thawing can affect label adhesion and legibility, so choose thermoplastic labels, which are more robust and ensure ink is resistant to all common laboratory solvents. For best practice, labels should be tested under at least the anticipated storage conditions prior to use. Label location and orientation should also be standardized. Labels should be placed directly under the tube cap and run straight along the tube length. Labels adhered in the wrong orientation, or those wrinkled or scrunched, make reading challenging and cause particular issues when using barcode scanners.

To eliminate the problems of physical labeling, tubes in which the barcode has been added by laser etching or integrated into the resin during molding can be used. As Armstrong explains “with permanent 2D barcodes, researchers no longer need to worry about misreading handwritten labels or labels falling off in the freezer or liquid nitrogen tanks”—reducing errors and saving time and labor.

Storage monitoring and maintenance

Once labeled and placed in storage, the integrity of your refrigerator or freezer is critical to protecting your samples—with malfunctions in your storage unit risking sample loss. Storage units should have continuous monitoring systems in place, including remote monitoring, that constantly evaluate temperature and performance, even when the lab is unattended. Audible alarms in addition to remote notifications should be used to alert you if the temperature changes outside of standard parameters and an emergency recovery plan should be in place. Alarms should be tested on a regular basis and freezer maintenance and service should be completed on schedule.

You should also be “prepared to respond to outside emergencies that can jeopardize equipment performance,” explains Armstrong. You can never guarantee that electrical power will not be disrupted so having a back-up energy generator will help you ensure samples remain “at the proper temperature, and you don’t lose months of research.” For additional safety, multiple samples sets should not be stored in the same unit, and fire prevention systems should also be in place. You may want to consider access and security features for valuable samples.

Sample location and tracking

Effective sample tracking is paramount in good sample management—as poor tracking “may cause samples to be misplaced or lead to unnecessary time looking for samples within the freezer,” states Armstrong.

Although physical logs or databases can be used, the use of an electronic LIMS system is now common best practice and can optimize sample tracking and lab efficiency—reducing manual labor, providing clear audit trails, and allowing easy updates if a sample location changes. “A LIMS acts as an additional member of the lab team, automating workflows and tracking all the important sample information, data, workflows, and QA/QC results generated each day,” states Armstrong. And as more standards governing the proper management of samples are released, including the relatively recent ISO 20387 Biotechnology-Biobanking-General requirements for biobanking, this visibility is becoming increasingly important.

Protecting your samples is paramount to the success of your research, and clear sample labeling, correct storage conditions, and organized tracking are key to this process. While traditional methods can be effective, more and more labs are adopting automation; realizing that eliminating manual labor can make sample management more efficient and minimize errors in lost or damaged samples. Ultimately explains Armstrong, labs are realizing that “compromising a long-term research project due to samples that were not stored properly, is not a risk worth taking.”