Environmental Field Sample Transportation - Best Practices to Ensure Sample Quality on Arrival at the Lab
The analytical results generated by our labs' spectrometers and gas chromatographs determine multi-million dollar remedial actions, regulatory settlements, and health risk assessments. Unfortunately, there is an opportunity for error, misunderstanding, and data misinterpretation before samples even arrive at the laboratory. Even the most carefully collected soil and water samples can provide misleading results if storage conditions are improper, the sample's ambient temperatures change, or crucial field documentation is missing upon arrival
There are a number of procedures that should be followed to ensure sample integrity during transit to the lab.
Cold Chain Preservation
Many environmental analyses, particularly those involving VOCs, SVOCs, and biological activity assessments require strict temperature control.
As a rule of thumb, most EPA methods will specify a US EPA 550 standard which indicates sample storage at at ≤6C (not frozen).
Some common best practices when it comes to temperature sensitive samples:
Thermal mass: use precooled containers & double bagged cubes of ice in transport rather than blue ice packs
Aim for containers that will maintain temperatures of at least 6°C throughout the duration of transport, especially tightly packed samples in the center of the container rather than near the walls.
A temperature blank within the sample container is often needed, as it allows testing labs to assess temperature conditions without having to puncture or open primary sample containers, which increases risks of exposure error, microbial contamination, or VOC/SVOC escape
Avoiding air gaps within the package will help protect against temperature fluctuations and breakage due to movement of the containers throughout transport. Best to fill empty spaces inside larger containers with bubble wrap, foam, or other packing materials.
Chain of Custody and Sample Documentation during Transport
A legal standard of proof is frequently applied to environmental testing and analysis. Any test result that could impact a legal decision or be used in an official capacity requires meticulous documentation of the sample's journey from the field to the laboratory. It is good practice to keep chain of custody documents protected throughout the sampling and transport process, especially if they may be needed later for forensic analysis or compliance reporting.
Missing field log, time, or location documentation, or lack of description of preservation methods used to maintain sample quality during storage or transit can create compliance issues upon arrival at the laboratory and possible rejection of the sample for retesting
Loose or improperly sealed transport containers
Lack of verifiable chain of custody or specialized transport documentation, especially with standard carrier companies that may not understand proper handling and chain of custody
Environmental companies and managers should utilize logistics and transport companies that specialize in environmental transportation and provide verifiable chain of custody and on-going lab temperature documentation for the life of the sample.
Preventing Physical Sample Breakage and Contamination During Transport
Field samples are frequently exposed to high vibration levels and pressure changes when transported by road. Glass containers, particularly those containing liquids, are especially prone to breakage and leakage.
Some basic transportation recommendations:
Upright containment: containers with liquid contents should always be transported upright to avoid pressure changes within the container and potential exposure of the container's interior to the analyte/contents, causing leaching, dissolution, or other unwanted reactions
Use secondary containment and/or specialized glass container bags in case of breakage during shipment
Make sure secondary packing materials are chemically compatible with any acids, bases, or other substances that may be present in the sample (nitric acid, HCl, NaOH are strong oxidizers and can weaken certain plastics, leach metals, or damage polymer film coatings)
Ensuring sample integrity during the field-to-lab transfer process is an important part of quality control and assurance in the environmental laboratory.
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