Frequently asked questions
Short, direct answers to the questions researchers ask us most, purity, certificates of analysis, water choice, storage, reconstitution math and where to find the tools that do the arithmetic for you.
Basics & compliance
Are Peptide.ST compounds intended for human or veterinary use?
No. Every compound supplied by Peptide.ST is sold strictly for in-vitro laboratory and research use only. They are not drugs, supplements, foods or cosmetics, and are not intended to diagnose, treat, cure or prevent any condition in humans or animals.
What does lyophilized mean?
Lyophilized means freeze-dried. The peptide is frozen and the water is removed under vacuum, leaving a stable powder or thin film at the bottom of the vial. In this dry state the peptide is far more stable and is shipped this way; it is brought back into solution (reconstituted) with bacteriostatic or sterile water before use in research.
Preparation & storage
What's the difference between bacteriostatic and sterile water?
Bacteriostatic water contains 0.9% benzyl alcohol, a preservative that inhibits bacterial growth and lets a reconstituted vial be used over multiple draws across several weeks when refrigerated. Sterile water is preservative-free and is intended for single-use reconstitution. Both are USP-grade options offered by Peptide.ST.
How do I calculate concentration after reconstitution?
Concentration equals the mass of peptide in the vial divided by the volume of water added. A 5 mg vial reconstituted with 2 mL gives 2.5 mg/mL (2500 mcg/mL). On a U-100 syringe, where 100 units equals 1 mL, each 10-unit mark then holds 0.1 mL, or 250 mcg. Our free reconstitution calculator does this for you.
How should peptides be stored?
Store lyophilized (dry) vials in a freezer at about -20 C, protected from light, where they stay stable for many months. Once reconstituted, keep the vial refrigerated at 2-8 C, minimise light exposure and avoid repeated freeze-thaw cycles. Always follow the storage guidance on the certificate of analysis for the specific compound. See our storage guide for the full walkthrough.
How long does a reconstituted vial last?
It depends on the compound and the water used. With bacteriostatic water and proper refrigeration, many peptides remain usable for several weeks; with preservative-free sterile water the window is much shorter and single-use is assumed. The certificate of analysis for your lot is the authoritative reference, and labelling the vial with its reconstitution date keeps you honest.
Quality & tools
Does every order include a certificate of analysis?
Yes. Every batch is third-party tested by HPLC and mass spectrometry and ships with a signed certificate of analysis documenting purity (98%+ on our research peptides), identity and lot traceability. You can look up a batch on the COA page.
Where can I work out concentrations and prep math?
The Peptide.ST Tools suite includes a reconstitution calculator and a research planner for organising compounds and concentrations. Remember that the figures on this site illustrate measurement math only, research quantities are defined by the study protocol and the relevant literature, not by us.