Aliquoting

Aliquoting is the process of dividing a larger sample into smaller, measured portions called aliquots. The practice aims to enable multiple analyses, preserve material, and reduce variability caused by repeated handling. The term aliquot comes from Latin aliquot, meaning some or several.

In laboratory practice, aliquoting requires careful planning: determine the required aliquot volume, total sample volume, and number of portions; select appropriate containers such as sterile microcentrifuge tubes or cryovials; use calibrated pipettes; label each aliquot with identity, date, concentration, and storage conditions; maintain a traceable chain of custody; work in a clean, ideally sterile environment to prevent contamination. For biological samples, aliquots are often stored at low temperatures to maintain stability; repeated freeze-thaw cycles should be minimized, with aliquots thawed only once when possible.

Procedure details include gently mixing when appropriate to ensure homogeneity, avoiding air bubbles, sealing containers to prevent evaporation, and recording the exact volumes and identifiers. Standard operating practices may also dictate steps for handling aerosols, risk assessment, and appropriate personal protective equipment.

Applications span biobanking, clinical chemistry, pharmacology, genomics, environmental testing, and toxicology. Aliquoting enables parallel testing, method development, quality control, and long-term storage, while reducing waste and preserving sample integrity for future analyses.

Considerations include risks of cross-contamination, sample loss, mislabeling, and degradation if storage conditions are not maintained. Minimizing handling, using appropriate sterile or sterile-like technique, and documenting aliquot origins and storage parameters are common best practices. Sub-aliquoting—the division of an aliquot further—is used to tailor portions for specific assays while maintaining traceability.