A vial of complement that leaves our freezer at −70 °C and arrives at yours still frozen has spent a day or two in the least controlled environment it will ever see, a courier network. Everything about how we pack and route it is built around that gap. This is what happens between the two freezers, and what you can do at your end so the reagent stays the one the lot certificate describes.
Why frozen matters
Most of what we ship is serum, plasma or complement, and complement sets the standard because it's the least forgiving. Hemolytic activity drops with every warming event, and a vial that thawed and refroze in transit will titer low with nothing on the label to warn you. Serum and plasma tolerate a brief excursion better but lose labile factors the same way. So frozen complement, serum and plasma go out on dry ice by overnight or two-day courier, while fresh tissue and whole blood go chilled on gel packs and are never frozen.
Dry ice
Dry ice sublimates at −78.5 °C, so a package stays well below −20 °C as long as any of it is left. The variable is how fast it goes, roughly 2 to 5 kg a day depending on the insulation and the ambient temperature, more in summer and on tarmac. We size the charge to the route with a margin for a one-day delay, use insulated shippers rated for the load, and leave the box vented so the CO₂ can escape. Dry ice is a regulated hazardous material in air transport (UN 1845), which is why the outer box carries the Class 9 label and net weight and the airway bill declares it. A package without those markings gets refused at the counter.
Borders
International shipments add paperwork, time and handling to the cold-chain problem. Customs and veterinary inspection can hold a package for a day or more, and every hold is dry-ice time. The documents that release it, the import permit, the health certificate and a correct commercial invoice, have to be right the first time; they're covered in regulatory documents for biological reagents. Packaging and labeling also have to meet the transport rules for biological materials. Institutional biosafety guidance, such as Boston University's chapter on transporting biological materials, summarizes the Department of Transportation and IATA requirements for classification, packaging and marking that apply to anyone shipping them (Boston University). For international routes we quote the courier service and the dry-ice charge for your destination when you order, so the package is packed for the route it will actually take.
At the receiving end
- Tell us the destination, the intended use and any import permit number when you order, not when the package is ready to go.
- Give us a delivery address where someone will receive the package and put it in a freezer the same day. A package left on a loading dock is a thawed package.
- On arrival, check that dry ice remains and the vials are hard-frozen before you sign. If they aren't, photograph the contents and contact us the same day.
- Move the product straight to the storage temperature on the label. Don't let it thaw a bit first.
- Record the lot number and the arrival condition with the shipment. It's the first thing to check if an assay drifts later.
When something goes wrong
Delays happen, and a delayed package isn't automatically a lost one. Complement that arrives cold but soft may still titer within specification, and we can advise on re-titering it before you make a decision. Contact us with the tracking number and what you found, and we'll work out the next step with you.