The Importance of Traceability When Transporting Frozen Samples

By Harshul Gupta (CTO), Keith Miller (CBDO), and Tulay Yucebas (Director of Continuous Improvement), Akuratemp LLC

Transporting frozen samples between laboratories is one of the most technically demanding aspects of the diagnostic cold chain. When physician office collections include frozen specimens, those samples must be frozen immediately after collection, packed correctly—often with ice packs—and placed into lockboxes. From there, the burden shifts to medical couriers, who are responsible for maintaining the frozen state during transport, often using dry ice in their totes.

To meet these demands, some advanced laboratory courier operations have innovated by installing freezer chests directly inside courier vehicles. These units are powered by the vehicle’s electrical system, with the idea that as long as the engine is running, the freezer will remain operational, protecting the frozen samples until they reach the diagnostic lab.

In theory, this solution closes a key gap in the chain of custody. But what happens when theory meets real-world courier routes?

Case Study: Temperature Variability in Vehicle-Installed Chest Freezers

To evaluate the real-world performance of vehicle-installed freezers, the Akuratemp team conducted a multi-day field study using 4G-enabled temperature sensors with geolocated probes. Four courier vehicles were outfitted with sensors placed inside their freezer units. Each courier operated a distinct route but repeated the same route daily to maintain consistency in the data. On the graph below the red line indicates the critical threshold temperature that should not be exceeded during transportation, and the other lines indicate the chest freezer temperature in reference to time per day. Knowing the courier route, the time data was matched with geolocation data to analyze the root cause of temperature variations.

Key Findings:

• Freezer temperatures rose rapidly during prolonged vehicle stops.
  
• After crossing the critical –10°C threshold, it took at least 30 minutes of continuous driving to return to acceptable levels.
  
• Stops longer than 10 minutes resulted in immediate internal temperature spikes.
  
• When freezers were not pre-cooled to –18°C before starting, even short idle periods pushed temperatures above safe limits.
  
• Some routes didn’t allow enough pre-drive time for the freezer to reach optimal temperature before the first pickup.
  

Root Causes Identified:

• Vehicles were launched before the freezer reached –18°C.
  
• Drivers turned off the engine, disabling the freezer, during deliveries or breaks.
  

Couriers opened the freezer door while the unit was off, allowing a surge in internal temperature.

Why Traceability Matters

These excursions were not only frequent but invisible without real-time monitoring. This presents a major risk: frozen samples may thaw unknowingly, compromising specimen integrity, delaying diagnostics, or leading to costly re-collections. A reliable traceability system is not just a regulatory or quality assurance requirement—it’s a safeguard for clinical reliability and courier accountability.

Recommendations for a More Resilient Frozen Transport Process

Based on our findings, we propose the following best practices to ensure compliance and performance:

Pre-condition the vehicle freezer: Idle the car and operate the freezer until it reaches –18°C before starting the route. Use Akuratemp Freezer Packs: Place one conditioned freezer pack per freezer section to support faster pull-down and temperature stabilization. Enable real-time temperature traceability: Equip freezers with smart temperature tracking and notifications to alert drivers of any excursion. Carry a validated frozen courier tote: Use a conditioned and validated tote for frozen transport during pickups. This allows samples to remain protected even when the vehicle freezer is off or being accessed repeatedly.

Looking Ahead

With frozen samples playing a critical role in molecular diagnostics, genetics, and infectious disease testing, ensuring sample integrity through every mile of the journey is non-negotiable. Technological upgrades like vehicle-mounted freezers are promising—but only if paired with validation, proper use, and real-time traceability.

The data doesn’t lie. By refining protocol and enhancing courier awareness with actionable alerts and validated packaging, laboratories can achieve full-chain visibility and control, preserving both patient trust and diagnostic accuracy.

Harshul Gupta
Chief Technology Officer
Akuratemp LLC
www.akuratemp.com