In liquid phase storage, samples are immersed directly in liquid nitrogen at -195.8 degrees C. In vapour phase storage, samples sit above the liquid nitrogen surface and are maintained at temperatures between approximately -150 and -190 degrees C by the cold nitrogen vapour. Vapour phase eliminates cross-contamination risk if straw seals are compromised and is now the preferred standard in UK HFEA-licensed units for human samples. Most Cryolab storage vessels support both configurations, with canister positioning determining which phase samples sit in.