Peptide Storage & Handling: Stability, Light Sensitivity, and Best Practices (Lab Guide)
Learn how to store and handle lyophilized and reconstituted peptides: temperature, light protection, moisture control, solvents, aliquoting, and COA tracking based on major lab suppliers’ guidance.
Key takeaways
Keep lyophilized peptides cold (≤ –20 °C), dry, and dark; warm to room temp before opening to avoid moisture uptake. MilliporeSigma+1
Solutions are short-lived at 4 °C (~1 week); for longer storage, freeze single-use aliquots and avoid freeze-thaw cycles.
Protect light- and oxidation-sensitive sequences (Cys, Met, Trp) with amber containers and minimized oxygen exposure.
Why storage & handling matter
Peptides are sensitive to temperature, light, moisture, pH, and oxidation. Poor control accelerates degradation (e.g., deamidation, oxidation, aggregation) and erodes assay reliability and yield. Best practice is long-term storage as a dry lyophilizate at sub-zero temperatures. MilliporeSigma
Ideal conditions at a glance
| Form | Temperature | Light | Moisture | Typical window |
|---|---|---|---|---|
| Lyophilized | ≤ –20 °C (–80 °C for longest term) | Dark | Desiccated | Months–years (sequence-dependent) MilliporeSigma+1 |
| Reconstituted (stock) | –20 °C or below (aliquoted) | Dark | N/A | Weeks–months (aliquots; no refreezing) MilliporeSigma |
| Working solution | 4 °C | Dark | N/A | ~1 week; prep fresh as needed MilliporeSigma |
Receiving lyophilized peptides: first steps
Let vials equilibrate to room temp in a desiccator before opening (hygroscopic—prevents condensation).
Weigh quickly; reseal tightly; return to cold, dark, dry storage.
Record lot #, mass, and link to COA (identity by MS, purity by HPLC). Bachem+1
Reconstitution & aliquoting
Plan concentrations so each aliquot is single-use.
Avoid freeze–thaw: make multiple small aliquots immediately after dissolving.
When pH > 8 is required, keep solutions chilled and store frozen when not in use. MilliporeSigma+1
Suggested workflow
Start with water or neutral buffer (PBS/Tris).
If insoluble, adjust by sequence chemistry:
Basic peptides (net +): add a small % acetic acid, then dilute.
Acidic peptides (net –): a small amount of NH₄OH, then dilute.
Hydrophobic sequences: dissolve in 100% organic (DMSO/DMF/ACN) first, then slowly dilute into aqueous buffer.
Note: Cys/Met/Trp sequences are oxidation-prone; use oxygen-reduced solvents and minimize DMSO for such residues. MilliporeSigma+1
Light & oxygen protection
Use amber glass or foil-wrap during prep and storage.
Minimize headspace; cap promptly; if possible, brief N₂/Ar purge for highly sensitive sequences (Cys/Met/Trp). Tocris Bioscience+1
Moisture control (critical for powders)
Lyophilized peptides are often hygroscopic. Always warm to room temp in a desiccator before opening, work efficiently, and store with desiccant. Moisture uptake lowers apparent content and stability. Bachem
Labeling, documentation & chain of custody
Maintain a sample sheet with: product name, sequence, lot #, COA link, form (lyo/solution), concentration, solvent, pH, aliquot size, prep date, operator, and storage location. This ensures traceability from COA (HPLC/MS) to each vial used. MilliporeSigma
Troubleshooting quick fixes
Won’t dissolve: change solvent per sequence; fully dissolve in a strong, compatible solvent, then slow-dilute into buffer. MilliporeSigma
Precipitates after dilution: increase ionic strength or add a small % ACN; prepare fresh. Tocris Bioscience
Cloudiness over time: probable aggregation/oxidation—use fresh aliquot; store colder; reduce oxygen and light. Tocris Bioscience
Lab checklist
☐ Verify lot and download COA
☐ Equilibrate closed vial to room temp in desiccator
☐ Weigh quickly, reseal, return to ≤ –20 °C
☐ Reconstitute, aliquot single-use, label concentration/pH/solvent
☐ Avoid freeze–thaw; protect from light & oxygen
☐ Update inventory & chain-of-custody sheet Bachem+1
FAQs
How long can peptide solutions sit at 4 °C?
Typically up to about a week; for longer periods, freeze aliquots at –20 °C or below. MilliporeSigma
Do I really need to warm vials before opening?
Yes. Most peptides are hygroscopic—warming prevents condensation that reduces stability and apparent content. Bachem
What’s the best long-term strategy?
Keep product lyophilized at –20 to –80 °C, protected from light and moisture; only reconstitute the amount you’ll use soon. MilliporeSigma+1
Which residues need extra care?
Sequences rich in Cys, Met, Trp are oxidation-sensitive; minimize oxygen, use amber vials, and avoid repeated thawing. Tocris Bioscience+1