Record reagent lot, final concentration, pH target, volume, date, preparer, sterilization method, storage condition, and any deviation from the usual recipe.
Supplements
Supplements often have different storage conditions from the base medium. Record when they were thawed, added, filtered, or aliquoted.
pH and osmolarity
For sensitive cultures or assays, pH and osmolarity can change interpretation. A recipe may be correct on paper but still unsuitable if preparation conditions drifted.
Working stocks
For working stocks, record the source stock, dilution factor, final concentration, solvent, storage temperature, and expiration or review date.
Practical checklist
- Keep recipes versioned.
- Record lot numbers for critical reagents.
- Note pH adjustment steps.
- Label storage condition clearly.
- Review old stocks before using them in important experiments.
Why this matters
A complete preparation record helps separate biological variation from preparation variation. It also supports reproducibility when another person repeats the same setup.