To reconstitute GHK-Cu, you add a measured volume of a suitable solvent, usually sterile water, to the vial of freeze-dried powder and swirl it gently until it fully dissolves into a clear blue solution. The concentration is simple maths: the milligrams of peptide in the vial divided by the millilitres of solvent you added. So 50 mg in 5 mL gives you 10 mg/mL.
Still choosing your material? Our GHK-Cu powder buyer’s guide explains what colour the powder should be, how to pick a vial size and what the certificate of analysis should show.
Below we go through it in plain English: picking a solvent, the step-by-step method, the maths (with a quick dilution example), what the blue colour tells you and how to store the solution. It is for laboratory research use only.
What GHK-Cu is, in one paragraph
GHK-Cu is a tiny peptide made of three amino acids (glycine, histidine and lysine) holding a single copper ion. The NIH PubChem record for GHK-Cu (prezatide copper) lists a molecular weight of about 403 g/mol for the complex. It occurs naturally in human plasma, and Loren Pickart, who first described it, has reviewed decades of lab work on it, including gene-expression studies (Pickart and Margolina, 2018, International Journal of Molecular Sciences). The key thing for reconstitution is that copper. Most of what can go wrong is about keeping it bound to the peptide.
Before you start: what you need for GHK-Cu reconstitution
- The certificate of analysis (COA) for your batch. You need the stated amount of peptide in the vial, and ideally the purity and identity results. Our guide to reading a peptide certificate of analysis explains what each line means.
- Your solvent, chosen to suit the experiment (more on that below).
- Sterile, accurate measuring kit: a calibrated pipette, alcohol wipes and gloves.
- Labels and a notebook, so the concentration, date and batch number are recorded the moment the vial is made up.
Choosing a solvent for GHK-Cu
GHK-Cu dissolves easily in water, so you rarely need anything exotic. The usual options are:
- Sterile water. The simplest, cleanest choice and the default for most lab work.
- A near-neutral buffer (for example, a phosphate buffer around pH 7) when the experiment calls for controlled pH.
- Bacteriostatic water. Sterile water with 0.9% benzyl alcohol to slow bacterial growth in vials that will be opened more than once. It is handy for general handling, but benzyl alcohol can interfere with some cell-based assays, so check it suits your method first.
What to avoid matters just as much. Acidic solvents, chelators such as EDTA and reducing agents such as vitamin C can strip or change the copper, leaving you with something other than intact GHK-Cu. We cover each of these in our guide to what not to mix with copper peptides.
How to reconstitute GHK-Cu, step by step
- Let the vial warm to room temperature before opening it. Opening a cold vial pulls in moisture, which can condense on the powder.
- Tap the powder down to the bottom of the vial so none is stuck under the cap.
- Wipe the rubber stopper with an alcohol wipe and let it dry.
- Measure your solvent accurately. Pick a volume that gives a round-number concentration (see the maths below).
- Add the solvent slowly down the inside wall of the vial, rather than squirting it straight onto the powder.
- Swirl or roll the vial gently. Do not shake it. GHK-Cu normally dissolves within a minute or two.
- Check the solution. You are looking for a clear, even blue with no particles or cloudiness.
- Label it straight away with the peptide, concentration, solvent, date and batch number.
GHK-Cu reconstitution maths made simple
Working out the concentration
There is only one formula you really need:
Concentration (mg/mL) = amount of peptide (mg) ÷ volume of solvent (mL)
- 50 mg vial + 5 mL solvent = 10 mg/mL
- 50 mg vial + 2.5 mL solvent = 20 mg/mL
One catch: the label weight is not always the exact peptide content. Lyophilised peptides can contain counter-ions and a little water, so the COA’s net peptide figure is the number to trust for careful work. If you would rather not do the sums by hand, our free peptide calculator will check them for you.
Making a weaker working solution (dilution)
Many experiments need a weaker solution than the stock. The standard lab shortcut is C1 × V1 = C2 × V2 (starting concentration × starting volume = final concentration × final volume).
Say you have a 10 mg/mL stock and want 10 mL at 1 mg/mL: 10 × V1 = 1 × 10, so V1 = 1 mL. Take 1 mL of stock and make it up to 10 mL with the same solvent.
Converting mg/mL to millimolar
Cell and chemistry papers often quote molar concentrations. Divide the mg/mL figure by the molecular weight in g/mol: 1 mg/mL ÷ 403 g/mol is roughly 0.0025 mol/L, or about 2.5 mM. Use the exact molecular weight on your COA, because salt forms vary.
Why GHK-Cu is blue, and what colour changes mean
The blue colour is the copper(II) ion itself. In GHK-Cu it is gripped by nitrogen atoms from the peptide, including one on the histidine. Researchers who solved the structure of the complex describe this binding in detail (Hureau and colleagues, 2011, Chemistry: A European Journal).
That makes colour a handy first check. A clear, consistent blue is what you expect. A shift towards green or brown, a fading colour, cloudiness or particles suggests the copper complex has changed, perhaps from the wrong pH, contamination or age. It is an early warning, not a substitute for proper testing.
Storing reconstituted GHK-Cu
- Keep it cold and dark. Use a fridge (2–8°C) for short-term use, in an amber vial or a box away from light.
- Aliquot it. Split the solution into single-use portions so the main stock is not opened again and again.
- Freeze what you will not need soon, and avoid repeated freeze-thaw cycles, which speed up breakdown.
- Keep unopened powder frozen, sealed and dry until you need it.
How long a solution stays good depends on the solvent and conditions, so labs should check stability for their own setup.
Common GHK-Cu reconstitution mistakes
- Shaking the vial hard instead of swirling it.
- Using an acidic solvent, or mixing in vitamin C or EDTA.
- Guessing the volume, then not knowing the true concentration.
- Using the label weight when the COA gives a different net peptide content.
Where Peptides UK fits in
Good maths only helps if the starting material is what it says it is. Our research-grade GHK-Cu comes with third-party HPLC and COA verification, so you can confirm identity and purity before any lab work. For the wider picture of the science, visit our GHK-Cu research hub. Questions about a batch? Email research@peptideslabuk.co.uk.
GHK-Cu reconstitution FAQ
What do you reconstitute GHK-Cu with?
Most labs use sterile water or a near-neutral buffer that suits their experiment. Bacteriostatic water also works for general handling, but it contains benzyl alcohol, which some cell-based work needs to avoid. Steer clear of acidic or chelating solvents, because they can pull the copper off the peptide.
How do I work out the concentration after reconstituting GHK-Cu?
Divide the amount of peptide in the vial (in mg) by the volume of solvent you added (in mL). For example, 50 mg in 5 mL gives 10 mg/mL. Always check the actual net peptide content on the certificate of analysis, and use our peptide calculator if you want to double-check the sum.
Why is my GHK-Cu solution blue?
The blue colour comes from the copper(II) ion held by the peptide. A clear, even blue is what you would expect from intact GHK-Cu. A colour shift towards green or brown, cloudiness or particles can mean the copper complex has changed and the solution should not be relied on.
Should you shake GHK-Cu to dissolve it?
No. Add the solvent slowly down the inside wall of the vial and swirl or roll it gently. GHK-Cu is very water soluble and usually dissolves within a minute or two. Vigorous shaking adds air and foam without speeding anything up.
How long does reconstituted GHK-Cu last?
There is no single answer, because it depends on the solvent, temperature, light and how often the vial is opened. General lab practice is to keep solutions cold and dark, split them into single-use aliquots and freeze anything not needed soon. Labs should check stability for their own conditions.
Is Peptides UK GHK-Cu for human use?
No. GHK-Cu from Peptides UK is supplied for laboratory research use only and is not for human or veterinary use.
For laboratory research use only. Not for human or veterinary use. This article is general lab and science education, not medical advice.
