Written by Scott Weitze
Shipping biological and molecular samples comes with multiple complications. Important factors to consider include leak prevention, sample integrity, legal compliance, and protection from dry ice acidification.
International and domestic regulations exist to protect shipped goods and humans involved in the shipping process. When a sample containing biological or molecular material is shipped by ground or air, the primary container should be certified to remain sealed and protect sample integrity during the changes in temperature and air pressure that can occur while the sample is in transit. Look for containers and sample tubes that are certified to IATA 95kPa/U.S. DOT/UN3373 standards. If the literature included with your container or sample tube does not contain an explicit reference to these standards, it has not been tested and should not be used. Using a container or tube without this certification puts the sender at risk for legal consequences, may cause leaking or contamination of the sample, and risks harm to anyone involved in the shipping process. Labcon® has many product lines that come with the assurance of validated certification for both air and ground shipping. Labcon’s SuperClear® Specimen Collection and Transport Tubes, ProtectR® CO2 Resistant Transport Tubes, and SuperClear® centrifuge tubes, are widely recognized for their best-in-class shipping performance and certifications.
The “95kPa Test” is the gold standard certification to validate a container’s suitability for the demands of sample shipping. In this test, a container/tube is tested for the ability to maintain a perfect seal across differences in air pressure and changes in temperature. The tube must maintain sample integrity and prevent leakage even when the pressure differential between the inside and outside of the container reaches 95 kilopascals (kPa). This is twice the pressure difference seen across a container barrier when the sample is in an unpressurized air cargo hold at a cruising altitude of 35,000 feet, as can be seen during air shipping. Anyone who has lost the contents of a soda bottle that was opened on a plane in flight has seen how air pressure makes containers leak, and the passenger compartment of an airplane controls air pressure to a greater extent than airplane cargo holds.
Importantly, a number of tube and container manufacturers may perform a portion of the 95kPa Test, and grant “full certification” to their shipping products, without performing the most critical component of the test: examining the ability of the tube/container to maintain a seal against a pressure differential during a large decrease and increase in temperature. The full 95kPa Test looks at seal integrity at room temperature, -40°C, and +55°C. A container certified to maintain a perfect seal at –40°C ensures the sample will not leak in the cold and depressurized conditions of an airplane cargo hold in flight. This critical and challenging component of many sample shipping paths and supply chains is too often ignored and can lead to catastrophic container failure and contamination. Testing container integrity at 55°C ensures that the elevated temperatures seen in truck cargo container shipping or equatorial locations will not adversely affect the container or sample during transport. In combination, the -40°C, and +55°C testing benchmarks ensure the container maintains robust function and sample integrity when shipping between lab locations.
When a container or tube states that it is “95kPa Certified”, you should ask for the protocol used or white paper that supports this claim. Again, many claims to 95kPa certified status have skipped the required temperature shift components of the experiment, are not actually certified, and put your sample integrity and shipping legality in jeopardy. Labcon® has performed full 95kPa certification testing on numerous products in their SuperClear® Specimen Collection and Transport Tubes, ProtectR® CO2 Resistant Transport Tubes, and SuperClear® centrifuge tubes product lines.
Most labs are unaware that shipping on dry ice can acidify even buffered samples by up to 2.5 pH units.This acidification can cause permanent damage to the sample, including a loss of solubility and functional material for proteins, antibodies, oligos, cell culture, and other biological reagents. The sample acidification occurs when carbon dioxide from sublimated dry ice enters tubes and containers, causing the formation of carbonic acid. (Incidentally, this is the same effect that increased atmospheric CO2 is having on the planet’s oceans.) This carbonic acid leads to a plunging pH in the sample. Most tubes aren’t designed to exclude carbon dioxide vapor under the still extremely cold sublimation temperature of dry ice. Failure to prevent this damaging reaction may contribute to the loss of active enzyme titer when shipping protein samples, amongst numerous other problems seen (or even happening undetected) when shipping samples on dry ice.
Labcon’s ProtectR® CO2 Resistant Transport Tubes are specifically designed to exclude cold carbon dioxide vapor, with a novel engineered design and proprietary polymer that protects samples from acidification even under the challenging conditions created by dry ice in ground and air cargo shipping. This product group remains the only tube containers on the market certified to protect biological samples shipped on dry ice, allowing for product and experiment consistency and reliability even when samples are shipped between different labs.
It is important to realize that shipping biological samples in tubes that are not tested and certified with a fully completed 95kPa test can lead to the loss of an important sample, inconsistent experimental results, and possible legal consequences. Additionally, some shipping conditions, like air and ground shipping on dry ice, should use specialized solutions engineered to protect samples from damage during transport.