Method · 5 min read
Why lot numbers matter more than you think in replicate work
Replicates only tell you something if the material behind them is the same. How lot tracking keeps that promise, and where it commonly slips.
Published 2026-10-23
A replicate experiment assumes that every replicate started from the same material. That assumption is rarely written down, so it is rarely checked. Lot numbers are the simplest way to check it.
What a lot number actually tells you
A lot number ties a vial to one production run and one batch record. Two vials with the same lot number came from the same run. Two vials with different lot numbers may differ in ways the label does not show, even when their names and pack sizes are identical.
Where lot tracking usually slips
- A second order placed mid-study that arrives under a new lot
- A vial moved between benches without its record
- A notebook that names the compound but not the lot
- A kit opened in a different order from the one planned
None of these is unusual. Each one can be prevented with a single line in the notebook entry: the lot number, written beside the sample ID, every time.
What to do when lots must change
Sometimes a study has to switch lots partway through. Plan a bridging step: run the old and new lots side by side for a short period and record the comparison. Reviewers accept a documented change far more readily than an undocumented one.