We’re always looking for ways to improve our shipment processes. After reading a publication describing how short term storage on dry ice can shift sample pH, we wondered whether or not the dry ice we use to keep viruses frozen during shipment was having an impact on the samples. We therefore devised a few experiments to determine if our tubes were permeable to the CO2 released from dry ice, and whether this affected the pH of our viral samples. Read on to learn how aqueous samples might be affected by dry ice, and specifically how dry ice can affect virus from Addgene.
Bottom line: there’s good news and there’s bad news. The bad news is that some of tubes’ o-rings are, in fact, permeable to CO2 at low temperatures (-80°C) and once in the tube, the CO2 can alter the pH of the liquid sample. The good news is that this effect is reversible and the pH shift can be prevented. Keep this information in mind if you’re planning on shipping something on dry ice or if you’re receiving samples on dry ice - it may prevent you from seeing some unexpected results.