GHK-Cu lyophilized is the copper tripeptide freeze-dried to a dry blue-violet cake. Learn why the solid form is used, how it looks, and how to store it.
GHK-Cu lyophilized is the copper-binding tripeptide glycyl-L-histidyl-L-lysine complexed with copper(II), supplied as a freeze-dried solid rather than a solution. Lyophilization removes water under vacuum from a frozen state, leaving a dry cake or powder — typically a distinctive deep blue-violet, since the Cu(II) coordination gives the complex its color. The dry form exists because the peptide-copper complex degrades measurably faster in aqueous solution than as a solid. A sealed lyophilized vial stored at -20 °C is a stable reference material for months to years; the same material in water at room temperature is not. Everything else on this page is about what that dry state means for purity documentation, storage, and what you actually pay for.
Freeze-drying is three stages: freezing (usually to between -40 °C and -50 °C), primary drying (sublimation of ice under vacuum, typically 50–200 microbar, at shelf temperatures of -20 °C to 0 °C), and secondary drying (desorption of bound water at 20–30 °C). The endpoint that matters analytically is residual moisture, and a well-run cycle lands under 3% w/w — many peptide lots come in at 1–2%.
That number is not cosmetic. Residual water is the substrate for the two dominant degradation routes in peptides: hydrolysis of the amide backbone and, in GHK-Cu specifically, copper-catalyzed oxidation of the histidine imidazole ring. Copper(II) is redox-active. A tripeptide holding a redox-active metal in a matrix that still contains 6% water is a slow reaction vessel. The same lot at 1.5% moisture is, functionally, a different stability product.
A supplier that reports moisture on the certificate of analysis is telling you something a supplier reporting only "purity ≥98%" is not. Ask for it. Many won't have it, because Karl Fischer titration or loss-on-drying adds $40–$120 per lot to the testing bill and most sellers skip it.
For a copper complex, two separate questions have to be answered, and a single number answers neither on its own.
A certificate showing 99% HPLC purity and nothing about copper stoichiometry documents a peptide, not a peptide-copper complex. Two different materials, one number.
Our approach to lot-level documentation is described on the quality page, and the broader documentation standards we apply across catalog items are covered in high purity peptides review.
The published stability ranges for lyophilized peptides are consistent enough to plan around:
Two failure modes get underweighted. First, freeze-thaw cycling of the sealed vial: every removal from the freezer causes condensation on cold glass, and if the stopper seal is imperfect that water enters the cake. Aliquoting a large vial into single-use units at receipt avoids repeated thermal cycling of the master stock. Second, light. The histidine-copper chromophore is photosensitive; amber vials or foil overwrap are not decoration.
Lyophilized cakes also have visual tells. A cake that has collapsed, shrunk from the vial wall, or fused into a glassy plug has likely been above its glass transition temperature at some point. A blue-violet powder that has gone brown, green, or grey suggests copper redox change. Neither observation replaces analysis, but both are free.
Pricing in this market spans a wide band and the spread is mostly documentation, not chemistry.
The 100x spread between bulk API and reference standard is real, and it is not markup for its own sake. Third-party HPLC purity runs $80–$250 per sample. ICP-MS for copper adds $60–$150. Karl Fischer moisture, $40–$120. Sterility or endotoxin testing, if applicable, $75–$200 each. A supplier doing all of that on every lot has $300–$700 in testing cost per batch before packaging, labeling, or storage. At 200 vials per lot that's $1.50–$3.50 per vial in testing alone — trivially absorbed. At 20 vials per lot it's $15–$35 per vial, which is why small-batch material costs what it costs.
Volume pricing structures are outlined under wholesale, and transit handling under shipping.
This is the part most supplier pages skip. Several situations where buying this material is a mistake:
Two further limitations worth naming plainly. Area-percent HPLC purity is not mass purity. A lot reported at 99% area purity by UV at 214 nm can still be 12% TFA salt and 3% water by mass, meaning your 50 mg vial contains roughly 42 mg of peptide-copper complex. If you are working gravimetrically, that gap is your error. And COAs are trivially forged. A PDF with a logo proves nothing. The check that works is requesting the raw chromatogram and mass spec trace with instrument metadata, and independently confirming that the named third-party lab performed the analysis — most labs will confirm a report number by email.
A workable checklist, roughly in order of how much information each step returns per dollar spent:
Retest intervals are the practical closer. Rather than treating a 24-month date as a cliff, re-run HPLC on a retained sample at the 12-month mark. A single $120 injection on retained material either extends your confidence in the remaining inventory or catches degradation before it contaminates a dataset. For catalog documentation and related material notes, the library index is the starting point.
Questions about lot documentation on a specific catalog item go through contact.
Supplied strictly for in-vitro laboratory research by qualified researchers and institutions. Not a drug, food, cosmetic or dietary supplement. Not for human or veterinary consumption. Not evaluated by the FDA.
Purity, identity and lot number, documented for the exact vial you receive.