Storing Reference Materials in the Laboratory: General Best Practice

General storage principles

Most reference materials are stable for extended periods when kept in a stable environment away from extremes of temperature, light and moisture. The starting point for any storage decision is the documentation that accompanies the batch, which typically indicates a recommended storage condition. Where no specific guidance is given, a cool, dry, dark location with minimal temperature fluctuation is the standard default across analytical laboratories.

• Keep containers sealed except for the brief period needed to subsample
• Avoid locations subject to direct sunlight or fluctuating room temperature
• Separate incompatible material classes according to standard chemical storage segregation
• Return containers to their designated location immediately after use

Choosing appropriate containers

The original supplier packaging is generally the most appropriate container for long-term storage, since it has been selected to be compatible with the material and to minimise exposure to air and moisture during normal handling. When material is transferred to a secondary container for day-to-day use, that container should offer an equivalent or better level of protection.

Controlling light exposure

A number of reference materials are sensitive to light and are supplied in amber glass, foil-lined packaging or opaque containers for that reason. As a general rule, any material not specifically confirmed to be light-stable should be stored away from direct or prolonged ambient light, and containers should not be left out on open benches longer than necessary during handling.

Managing temperature and humidity

Temperature and humidity control protect against two related risks: chemical degradation accelerated by heat, and physical changes such as clumping or moisture absorption. Laboratories typically categorise their reference material stock into a small number of storage bands — for example, ambient room temperature, cool storage, or refrigerated storage — based on supplier guidance, and route incoming stock to the appropriate location as part of the receiving process.

• Use a dedicated, monitored storage unit rather than a general-purpose refrigerator or cupboard where possible
• Log temperature at a regular interval and flag any excursion outside the expected range
• Include desiccant or humidity control in storage areas prone to moisture, particularly in coastal or humid climates

Secure storage and access control

Physical security is as much a part of storage practice as environmental control. Reference materials should be kept in a lockable cabinet, room or refrigerator with access limited to trained, authorised personnel, and any access outside normal working hours should be logged.

• Restrict keys, key codes or access cards to a defined list of authorised staff
• Keep a signing-in log for any out-of-hours access to storage areas
• Review the access list periodically and remove staff who no longer need it
• Store higher-control materials in a separate, more restricted area from general laboratory consumables

Linking storage practice to inventory and labelling

Storage does not operate in isolation — the location a container is assigned to should be recorded in the laboratory's inventory register and reflected on its label, so that any staff member can locate material quickly without opening multiple cabinets. Aligning storage location, label and register also makes stock reconciliation and periodic audits considerably faster, since discrepancies between where something should be and where it actually is become immediately visible.