Quick answer: A GLOW vial holds 70 mg of co-lyophilized peptide: 50 mg GHK-Cu, 10 mg BPC-157 and 10 mg TB-500. To reconstitute it, let the vial reach room temperature, add a measured volume of diluent slowly down the glass, and swirl until the blue cake dissolves completely. Each component's concentration is its mass divided by the volume added; 5 mL, for example, gives 10 mg/mL GHK-Cu and 2 mg/mL each of BPC-157 and TB-500. Keep the dry vial at −20 °C and the solution at 2–8 °C, protected from light, for up to about 28 days.
This guide covers the volume math and bench handling for the GLOW stack in detail. For laboratory research use only; not for human consumption.
What is in the vial
GLOW is a fixed 5:1:1 mass-ratio blend. Because all three peptides are freeze-dried together, the ratio cannot be altered after the fact, and every aliquot drawn from the reconstituted solution carries all three components in the same proportion.
| Component | Mass per vial | Approx. molecular weight | Amount per vial |
|---|---|---|---|
| GHK-Cu | 50 mg | ≈ 404 g/mol (copper complex) | ≈ 124 µmol |
| BPC-157 | 10 mg | ≈ 1,419.5 g/mol | ≈ 7.0 µmol |
| TB-500 | 10 mg | ≈ 4,963 g/mol | ≈ 2.0 µmol |
| Total | 70 mg | – | – |
The molar picture is very different from the mass picture: by mole, GHK-Cu outnumbers TB-500 roughly sixtyfold. Background on each component is in the GLOW peptide blend overview.
Before reconstituting
- Check the paperwork. Match the lot number on the vial to its certificate on the COA page and note the reported purity and identity results.
- Inspect the vial. The cake or powder should be blue to blue-violet, a consequence of the copper(II) bound to GHK. The seal and stopper should be intact.
- Equilibrate. If the vial has been in a freezer or refrigerator, leave it sealed at room temperature for 20–30 minutes. Opening a cold vial draws moisture from the air onto the hygroscopic powder.
- Gather materials. Diluent, sterile syringes or calibrated pipettes, alcohol swabs, gloves, a permanent marker, and sterile low-binding tubes if aliquots are planned.
Choosing a diluent
Bacteriostatic water, which is sterile water containing 0.9% benzyl alcohol as a preservative, is the usual choice when a vial will be accessed more than once, because the preservative inhibits microbial growth between withdrawals. Plain sterile water is suitable when the whole volume will be used or aliquoted and frozen in one session. Avoid diluents and downstream buffers containing strong chelators such as EDTA at meaningful concentrations: they can strip copper from GHK and change the nature of the largest component in the blend.
Volume math: concentration by diluent volume
The governing formula is simple:
Concentration (mg/mL) = mass of component (mg) ÷ diluent volume (mL)
Apply it to each component separately. The table covers common volumes.
| Diluent added | Total peptide | GHK-Cu | BPC-157 | TB-500 |
|---|---|---|---|---|
| 2 mL | 35 mg/mL | 25 mg/mL | 5 mg/mL | 5 mg/mL |
| 3 mL | 23.3 mg/mL | 16.7 mg/mL | 3.33 mg/mL | 3.33 mg/mL |
| 5 mL | 14 mg/mL | 10 mg/mL | 2 mg/mL | 2 mg/mL |
| 7 mL | 10 mg/mL | 7.14 mg/mL | 1.43 mg/mL | 1.43 mg/mL |
| 10 mL | 7 mg/mL | 5 mg/mL | 1 mg/mL | 1 mg/mL |
Volumes of 5 mL and 10 mL produce round numbers for every component, which simplifies downstream calculations. Confirm that the vial's physical capacity accommodates the chosen volume; if it does not, dissolve the cake in a smaller volume first and transfer quantitatively to a larger sterile container before bringing it up to the final volume.
Molar concentrations
Many assays are specified in molar terms. At the 5 mL volume:
- GHK-Cu: 10 mg/mL ÷ 404 g/mol ≈ 24.8 mM
- BPC-157: 2 mg/mL ÷ 1,419.5 g/mol ≈ 1.41 mM
- TB-500: 2 mg/mL ÷ 4,963 g/mol ≈ 0.40 mM
Halve those figures for 10 mL; multiply by 2.5 for 2 mL.
Volume needed for a target mass
To find the volume that contains a target mass of one component, divide the mass by that component's concentration. At the 5 mL reconstitution:
- 500 µg of GHK-Cu is contained in 0.5 mg ÷ 10 mg/mL = 0.05 mL (50 µL).
- That same 50 µL also carries 100 µg of BPC-157 and 100 µg of TB-500.
- A 100 µL aliquot contains 1 mg GHK-Cu, 200 µg BPC-157 and 200 µg TB-500, or 1.4 mg of peptide in total.
This coupling is the central constraint of working with a blend: choosing the amount of one component fixes the amounts of the other two.
Preparing working dilutions
Use C1V1 = C2V2. To prepare 1 mL of a working solution at 100 µg/mL GHK-Cu from the 10 mg/mL stock, combine 10 µL of stock with 990 µL of buffer. The same working solution will contain 20 µg/mL each of BPC-157 and TB-500. The calculator can be used to check any of these figures.
One caveat applies to all peptide math. Label masses are nominal; lyophilized peptides contain counter-ions and residual water, so net peptide content is somewhat below gross mass. Where exact molarity is critical, use the content figures on the certificate of analysis.
Step-by-step reconstitution
- Step 1. Remove the cap and wipe the stopper with an alcohol swab. Wipe the diluent vial's stopper as well and let both dry.
- Step 2. Draw up the planned volume of diluent with a sterile syringe.
- Step 3. Pierce the stopper at a slight angle and direct the stream against the inner glass wall, not onto the cake. Lyophilized vials are often under partial vacuum, so control the plunger and let the liquid run in slowly.
- Step 4. For larger volumes, add the diluent in portions, releasing built-up pressure between additions.
- Step 5. Swirl gently or roll the vial between the fingers. Do not shake or vortex; TB-500 is a 43-residue peptide, and vigorous agitation promotes foaming and aggregation.
- Step 6. Allow a few minutes for complete dissolution. The finished solution should be a clear, uniform blue with no visible particles.
- Step 7. Label the vial with the date, the volume added and the concentration of each component.
General technique is covered more fully in how to mix peptides with bacteriostatic water.
What a correctly reconstituted solution looks like
Expect a transparent blue liquid; the depth of color scales with GHK-Cu concentration, so a 2 mL reconstitution is visibly darker than a 10 mL one. The following observations warrant setting the vial aside and investigating:
- Persistent cloudiness or visible particles after adequate swirling time.
- A shift toward green or brown, or loss of color, which can indicate changes to the copper complex.
- Turbidity developing during storage, a possible sign of microbial growth or aggregation.
Storage
Lyophilized vial
Store sealed vials at −20 °C for the long term, in the dark and away from moisture. Refrigeration at 2–8 °C is adequate for the short term. Avoid frost-free freezer compartments that cycle through warm phases, and keep vials in a sealed secondary container with desiccant where possible.
Reconstituted solution
Refrigerate at 2–8 °C immediately after mixing and protect from light. With bacteriostatic water, plan to use the solution within about 28 days. Keep it off the refrigerator door, where temperature swings are greatest, and return it promptly after each withdrawal. Swab the stopper before every access.
Aliquoting and freezing
If the solution will not be used within the refrigerated window, divide it into single-use aliquots in low-binding tubes and freeze at −20 °C or below. Thaw each aliquot once, gently, and discard any remainder. Repeated freeze–thaw cycles stress peptides, the larger TB-500 component in particular. More detail is available in storing research peptides.
Common errors to avoid
- Calculating from the 70 mg total when the protocol specifies a single component.
- Opening a cold vial and letting condensation reach the powder.
- Spraying diluent directly onto the cake or shaking to speed dissolution.
- Leaving the reconstituted vial on the bench between uses.
- Mixing with EDTA-containing or strongly reducing buffers that disturb the copper complex.
- Failing to record the diluent volume, which makes every later calculation unverifiable.
The two-peptide version of this workflow is described in BPC-157 + TB-500 blend reconstitution.
Frequently asked questions
How much diluent should be added to a 70 mg GLOW vial?
There is no single required volume. The choice sets the concentration: 2 mL gives 35 mg/mL total, 5 mL gives 14 mg/mL and 10 mL gives 7 mg/mL. Volumes of 5 mL or 10 mL give round per-component figures, provided the container can hold them.
Why is the GLOW solution blue?
The color comes from the copper(II) ion bound to the GHK tripeptide. A clear blue solution is the expected result. Cloudiness, particles or a change toward green or brown are not expected.
How long does reconstituted GLOW keep in the refrigerator?
Up to about 28 days at 2–8 °C when prepared with bacteriostatic water, protected from light and handled aseptically. For longer periods, freeze single-use aliquots and avoid repeated freeze–thaw cycles.
Can the concentration of one component be changed independently?
No. The 5:1:1 mass ratio is fixed when the blend is lyophilized. Diluting the solution lowers all three concentrations together. Designs that need to vary one peptide on its own require separate single-component vials.