Freeze-Thaw Cycles and Aliquoting

Record each aliquot's parent

Start with the source vial and supplier lot. Give the preparation its own identifier and give each aliquot a separate identifier beneath it. The research lot log links those records so that an event affecting one portion can be traced back without changing its siblings’ histories.

Record the concentration and the basis for that value. If it was calculated, retain the target mass or amount and the final volume used in the calculation. The mass and molarity guide explains those units.

Count events consistently

In this fictional record, DEMO-A and DEMO-B both came from preparation DEMO-P. DEMO-P had one recorded thaw before division. Later, DEMO-A was thawed for an assay while DEMO-B stayed in storage. Both inherit the parent’s event. Only DEMO-A acquires the later event.

Use your laboratory’s definition of a freeze–thaw event consistently. If a portion was found partly thawed and its time outside storage is unknown, enter the observation and the gap. A count alone cannot reconstruct the conditions or demonstrate retained activity.

Ask what the stability evidence covers

For an acceptance decision, compare the material, solvent, concentration, container, temperature history and measured attribute with the applicable product specification or stability record. ICH Q5C describes evidence tied to the presentation and conditions in its biological medicinal-product setting. It provides no general cycle allowance for these research materials. ^[1]

For an uncertain exposure, use temperature excursion records to document what was measured. For the underlying supported storage condition, see storage and stability. Record who assessed the affected aliquot and what evidence supported its status.

If an aliquot behaves unexpectedly during an assay preparation, keep its identifier with the preparation troubleshooting record. Other research guides cover the associated preparation, calculation and storage questions.

Other records for this assessment