Temperature Excursion Management

A temperature excursion is an event in which a material’s storage temperature falls outside the defined range for a period of time. For research materials with a specified storage condition, any deviation from that condition constitutes an excursion. Excursions may be brief and minor, such as a freezer door left open for a short time, or more significant, such as a refrigeration failure that allows material to warm to room temperature over several hours. The significance of an excursion depends on both the magnitude of the temperature deviation and its duration. This overview is educational and describes management practices; it contains no guidance on the use of any material.

Temperature monitoring equipment

Continuous temperature logging devices placed within storage units provide a time-stamped record of the temperature experienced by stored materials. These loggers can be standalone electronic units or connected to a centralised monitoring system. Reviewing the log after a suspected excursion event allows the duration and extent of the deviation to be determined accurately. Min-max thermometers, which record only the highest and lowest temperatures reached since their last reset, provide a simpler but less detailed indication of whether the storage unit has remained within range.

Alarm systems

Many laboratory cold storage units include built-in temperature alarms that alert operators when the temperature rises above or falls below a set threshold. Connecting alarms to a remote monitoring system, such as an audible alarm or an automated notification, means deviations can be detected promptly even when laboratory staff are not present. The earlier an excursion is detected, the sooner corrective action can be taken.

When an excursion is detected, the first step is to establish its duration and severity using temperature logs or other available data. This information is then used to assess the potential impact on the material. An excursion assessment considers how long the material was outside its specified range, the temperature it reached, and whether the material has a defined stability profile that can be consulted.

For research materials without a formal stability profile, the assessment is more general: was the excursion brief and modest, or was the material exposed to conditions significantly outside its specification for an extended period? Materials that experienced a severe or prolonged excursion may need to be quarantined and assessed before further use, with the decision documented in the laboratory records. For general guidance on storage conditions, see Peptide Storage Guidelines.

Every temperature excursion should be documented, regardless of its assessed severity. The record should include the date and time the excursion was detected, the temperature data showing the extent and duration of the deviation, an assessment of the materials affected, the decision made regarding those materials, and any corrective or preventive actions taken. Thorough documentation of excursions provides an accurate history of storage conditions for each material and creates a basis for investigating patterns if excursions recur.

Where the decision is made to continue using material that has experienced an excursion, that decision and its basis should be clearly recorded. Where material is quarantined or discarded, this too should be noted. Avoidable labelling and record gaps are discussed in Common Laboratory Storage Mistakes.

Many temperature excursions are preventable. Practical preventive measures include ensuring cold storage units are not overfilled, which can impair air circulation and temperature uniformity; avoiding leaving doors open unnecessarily; monitoring the condition of door seals and replacing worn seals promptly; keeping a log of routine temperature checks; and having a contingency plan for moving materials to alternative storage in the event of equipment failure.

Backup power supplies for cold storage units can prevent excursions during power outages. Where critical materials are stored, maintaining a secondary storage location provides additional protection. Planning for excursion management before an event occurs, rather than improvising in the moment, reduces both the duration of excursions and the likelihood that materials are compromised. Excursion management is one aspect of the broader material lifecycle, from receipt through to disposal; for an overview of how these stages connect, see Research Material Lifecycle Management. Our approach to material storage and quality is described on the Quality page.