Ambient, 2–8 °C, −20 °C, −80 °C, LN2: Choosing the Right Lane

Every sample has a stability window — the time it remains valid at a given temperature. The lane you choose should keep the sample comfortably inside that window for the realistic transit time, with margin. Colder is not automatically safer: each step down adds packaging complexity, coolant mass, customs attention, and cost.

The five lanes and when they fit

• Ambient / CRT (15–25 °C): dried blood spots, swabs with medium, most stabilized nucleic-acid tubes
• 2–8 °C: whole blood for many hematology and serology panels; conditioned gel packs do the work
• −20 °C: plasma, serum, some enzymes — frozen gel or dry ice supplement
• −80 °C: cell-free DNA fidelity, many microbiome protocols — dry ice, budgeted to arrival
• LN2 dry vapor (≤ −150 °C): cells, gametes, tissue for culture — dry shippers preconditioned and monitored

The receiving laboratory's sample manual is the authority — start there. We translate its requirements into the lane, packaging, and coolant plan.