Storing and handling peptides properly.
A batch's certificate of analysis describes the day it was measured. Whether the vial still matches it six months later is decided entirely by how it's stored and handled.
Why peptides degrade at all.
Peptides are chains held together by amide bonds, decorated with side chains that chemistry can attack. Water hydrolyzes the backbone; oxygen oxidizes methionine, cysteine and tryptophan residues; heat accelerates everything; light drives its own reactions; and in solution, chains can clump into aggregates that no longer behave like the monomer. Every degradation product is a new impurity — mishandling quietly rewrites the purity number a batch was verified at.
Lyophilization — freeze-drying — is the defence. With the water removed, hydrolysis effectively stops and every other pathway slows dramatically. A sealed lyophilized vial, kept cold and dark, is a remarkably stable object. Nearly all storage failures happen after the seal is broken or the water goes back in.
The rules for sealed vials.
- Frozen is the standard: −20 °C for storage, per the guidance printed on every Sentir product page. Short of a freezer, a refrigerator (2–8 °C) preserves sealed vials well over practical timescales.
- Dark matters — store vials away from direct light; a closed box in the freezer is ideal.
- Let cold vials warm to room temperature before opening. Opening a freezer-cold vial invites condensation onto the cake — reintroducing exactly the water lyophilization removed.
- Keep the vial sealed until the day it's used. The stopper's integrity is the storage system.
Reconstitution: bringing the peptide into solution.
Laboratory practice is to reconstitute gently. Add the solvent slowly, letting it run down the vial wall rather than jetting onto the cake, and dissolve by swirling or slow rolling — never vortexing. Peptides are physically delicate in solution, and aggressive agitation promotes the aggregation you're trying to avoid. Most lyophilized research peptides dissolve within a few minutes; larger molecules like IGF-1 LR3 deserve extra patience and the gentlest touch in the catalog.
Solvent choice depends on the protocol. Sterile bacteriostatic water is the common laboratory default for stock solutions; plain sterile water suits immediate single-use preparations. A few sequences are stubborn at neutral pH — very hydrophobic or highly charged chains sometimes need a small first volume of dilute acetic acid or another protocol-specified vehicle before dilution to working concentration. The compound's literature and your protocol outrank any general rule, including this one.
Concentration is a choice, not an accident: decide the target concentration first and calculate the solvent volume, rather than discovering the concentration afterwards. Our reconstitution calculator does the arithmetic — mass and volume in, concentration and molarity out.
The rules for reconstituted solutions.
- Refrigerate at 2–8 °C, and treat the solution as short-lived — use it within the window your laboratory protocol defines.
- Never re-freeze a solution casually. Freeze-thaw cycles are among the most damaging events in a peptide's life; if a protocol requires frozen aliquots, freeze single-use volumes once.
- Aliquot on day one. Splitting a stock into single-experiment volumes means each experiment draws on once-thawed material and the stock is never repeatedly opened.
- Label with contents, concentration, solvent and date — future-you is a different person with a worse memory.
- Watch for trouble: visible cloudiness, particulates or gelation mean aggregation, and that solution no longer represents the batch's COA.
Compound-specific notes from our catalog.
- GHK-Cu dissolves blue. That's the copper complex itself — expected, and mild confirmation the complex is intact.
- NAD+ is hygroscopic and unstable warm or alkaline in solution: keep the powder rigorously dry, prepare solutions fresh and cold.
- Glutathione is supplied reduced, and its free thiol slowly air-oxidizes in solution — fresh preparation is the whole game.
- CJC-1295 carries a reactive DAC linker by design: handle solutions promptly and avoid thiol-containing buffers that would quench it.
- Cyclic and short peptides (MT-II, KPV) are the hardiest things in the catalog — which is a reason for good habits, not an exemption from them.
Common questions.
Kept sealed at −20 °C away from light, lyophilized peptides commonly remain within specification for years. The enemies are moisture, heat, light and broken seals — not time itself.
It's the standard choice for stock solutions that will be drawn from more than once. Plain sterile water is fine for immediate use; some sequences need a protocol-specified vehicle. Follow the compound's literature over any blanket rule.
Repeated freeze-thaw cycles measurably degrade peptides, so the honest answer is: not casually. Where a protocol requires frozen storage of solution, freeze single-use aliquots once and thaw each exactly one time.
