Storing and Tracking Samples: Preserving Contents and Managing Sample Data
Samples are precious resources and integral to the research process. The information derived from them is dependent on their quality, integrity and consistency. And, many samples represent a scientist’s investment in and trust of the biomedical research process. Yet, it is not unusual for samples to go missing, to find that their labels have fallen off or that they have become unusable because of evaporation or temperature variations in a poorly organized freezer.
Thankfully, problems like these are avoidable. In fact, focusing on two critical aspects of sample management—protecting the sample material itself and managing sample data—can help ensure that these and other costly, resource-intensive pitfalls don’t occur in laboratories.
Many factors can affect sample quality, including handling and processing. Following these best practices will help ensure that samples are maintained in optimal condition.
Storage tube quality
When selecting the right storage tubes for your laboratory, consider the range of factors that influence specimen quality. Foremost is the sterility level of storage tubes. Contamination can negatively impact many sample types, especially biological samples, and compromise downstream analysis and results. For example, RNA is particularly sensitive to RNase gene family, which may be present on tools and surfaces that have not been properly sterilized. Look for the higher sterility assurance levels (SAL) of 10-6 or 10-3.
Other features of high-quality storage tubes include that they:
- Are contamination-free (DNase, RNase, DNA, pyrogen, endotoxin, cytotoxin).
- Have an additive-free manufacturing process.
- Are made from virgin medical-grade raw materials which are free of heavy metals.
High-quality storage tubes are made using regulated manufacturing processes and have stringent product validation processes. A storage tube supplier should be able to provide documentation supporting product and material quality.
When it comes to sealing samples, many options exist. Seal integrity of the storage tube must maintain the quality of the sample contents as well as prevent evaporation and contamination from outside the tube. It’s important to remember that when shipping blood, urine, fluids and other specimens containing or suspected of containing infectious substances that all samples must be packaged and labeled according to applicable government and International Air Transport Association (IATA) regulations.
Heat-sealing tubes with a pierceable foil seal offers an easily accessible, low-profile and cost-effective option for securing samples. Sealed tubes can be pierced easily with manual or automated pipette tips, and the low-profile seal is highly compatible with downstream automated storage equipment for storage at temperatures ranging from -196 to 25 C. Sealing is fast and requires minimal heat to be effective.
For samples requiring storage at cryogenic temperatures, tubes selected often include a soft-material gasket—typically comprised of silicone rubber—to form a high-integrity seal between the tube and cap. Alternatively, thermoplastic vulcanizates (TPV) materials are also used for cap gaskets, and due to limited gas permeability properties, provide enhanced seal performance at temperatures above freezing, such as room temperature. These TPV materials can also be molded over the polypropylene cap material, forming a single piece construction. The single-piece construction prevents cap over tightening during manual capping procedures, which can result in gasket extrusion and a compromised cap/tube fit.
Whether semi- or fully automated, capping and decapping tools provide an opportunity to ensure seal integrity of screwtop style tubes and closures while increasing throughput by approximately 10 times per rack of tubes. These useful tools provide alternatives to tedious manual capping by reducing repetitive stress and securing caps to their recommended torque level, to ensure sample integrity and prevent loss during storage and transportation.
Not only do researchers have to worry about the integrity of samples, they also have to track and manage tubes to ensure they’re reliably logged in and out of a laboratory’s database or laboratory information management system (LIMS). There are many moving parts of a laboratory, and several researchers may handle the same sample throughout the several stages before, during and after the storage process. Tracking the location and status of samples can be challenging in any environment, and as the number of samples stored increases, so do the challenges. But proper labeling and barcoding, barcode readers and database systems can help.
Labels and unique identifiers
Every sample should have a unique identifier or combination of identifiers that are firmly affixed, or a permanent part, of the container. Options for identification include human readable (no scanner required for reading), linear barcodes and 2-D barcodes. Guaranteed uniqueness from a supplier is key to ensuring that identifiers are indeed unique. Combinations of 2-D, 1-D and human readable codes enable easy sharing of samples between sites with various levels of barcode reading technology. This combination of features is appealing to hospital systems, which may have multiple laboratories handling samples.
Whichever is used, the label should be clearly and legibly marked and able to withstand all potential storage and transportation conditions. Single-piece construction of tube and code is critical to ensure the tube and code are never separated. This configuration helps prevent the researcher from scanning one tube and mixing up components from another tube, causing an incorrect result. This type of mistake often goes undetected and can lead to false positive or false negative result.
When selecting the most compatible method of sample identification, look for stability under long-term storage conditions appropriate for the intended storage material. Guaranteed readability of the 2-D code is critical. Designs that protect 2-D codes ensure that the sample can be identified after exposure to storage, processing or transportation conditions. Laser-etched 2-D barcodes ensure permanent and secure sample tracking with high-contrast codes that can be read even with frost present.
2-D barcode readers
Laboratories of all sizes can use 2-D barcode readers to decode nearly any type of 2-D barcoded storage tube, in multiple configurations. Key features of 2-D barcode readers include:
- Simple connectivity to laboratory computers.
- Ability to export barcode data to a database or LIMS system.
- Features that allow 1-D and 2-D barcode readability through frost or in cold rooms.
- Features that support orientation detection for full rack reading.
- Ability to decode multiple 2-D and linear barcode formats.
- Sealed unit to prevent frost and condensation buildup, which enables reading of ice-cold tubes at ambient temperatures.
- Optional linear barcode accessory for reading and integrating codes on the sides of racks.
Storage tracking systems
2-D barcoded data can be integrated into existing databases and tracking systems or used as part of a larger integrated system or LIMS to track sample data and storage location.
Knowing exactly where samples are located minimizes the time spent trying to find them with the freezer door open, which risks optimal performance of the freezer unit, exposing other samples to warmer temperatures and exposing laboratory staff to very cold temperatures.
Storage tracking systems are a good option for laboratories for which paper notebooks and Excel spreadsheets are no longer efficient, but powerful custom databases are too costly.
Key functionality of these systems include:
- Intuitive and easy-to-use interface.
- Straightforward searching, sample addition and sample disposition.
- Ability to import data from external sources, such as .xml or .txt files.
- Ability to back-up data to local or networked locations.
- Administrator and user-level access to maintain robust chain of custody.
- Audit history tools.
Today’s laboratories are faced with many challenges when it comes to preserving the integrity and utility of samples. While not all factors are in your control, selecting the right storage tubes for a laboratory’s needs and using smart systems for organizing and tracking samples can help ensure that they remain easily accessible and in optimal condition, while increasing laboratory efficiency.
When selecting products, seek out companies that are known for their customer support resources, including technical and application support, and that have specialized sales forces that are experts on storage tubes and cold storage equipment.