Background and Aim: To determine if there is a significant difference in specimen level temperature between new cryostorage labware and traditional canes and goblets when handling through ambient conditions.
Methods: Vapor nitrogen storage (<–170°C) offers advantages in weight and safety while enabling automated storage and retrieval systems. We designed labware to maintain cryogenic temperatures while safely transitioning specimens through ambient temperatures. The devices consist of vessels analogous in use to goblets (TRT1), and combined vessels and holders (TRT2)—analogous to canes and goblets (CON). The rate of temperature rise to –100°C resulting from liquid nitrogen (LN2) evaporation was determined for the CON and TRT1. The rate of temperature rise from LN2 temperatures was determined for CON and the rate of temperature rise from vapor nitrogen temperatures (∼–180°C) for TRT2. Temperatures were collected using 36-gauge T-Type thermocouples every second at the specimen level. The t-test was used to determine significant differences between controls and treatments.
Results: The rate of temperature rise was significantly greater (P<0.001) with CON (n=5, 0.62±0.05°C/s) than TRT1 (n=5, 0.33±0.08°C/s). The rate of temperature rise to -100°C was significantly greater (P<0.001) with LN2–containing CON (n=5, 0.58±0.02°C/s) than the vapor phase starting temperature TRT2 (n=10, 0.12±0.01°C/s). The mean specimen-level starting temperature of the TRT2 assemblies was –181.64±2.11°C, compared with a LN2 starting temperature of –195.8°C for CON. Even with the lower starting temperature, the mean±SD time to –100°C for LN2–containing goblets (165.0±4.4 s) (CON) was highly significantly (P<0.001) quicker than the vapor nitrogen (TRT2) assemblies (693.5±33.2 s).
Conclusions: All labware studied maintained cryogenic temperatures below -132°C for 15–30 s, allowing for safe handling under normal conditions. LN2 spillage, which may reduce the time to -100°C for the canes and goblets, was not studied. The increased time and thermal protection afforded by the new labware lessens the likelihood of a thermal excursion during mishandling, and its thermodynamics represents an improvement in temperature stability. Reduction of temperature changes from vapor storage temperatures for the new labware allows for confident movement through ambient temperatures, without jeopardizing specimen safety, while using automation to improve the working conditions of embryologists.
© 2022 Published by Elsevier Inc.