How to reconstitute peptides

You need the sealed peptide vial, a sterile solvent, a sterile syringe for measuring volume, alcohol wipes for the stoppers and a label. Everything else is technique.

A clean bench and a fridge thermometer finish the kit. The syringe is a measuring tool here. Its scale decides how precisely you can split a solution later.

Check the vial against its certificate before you puncture the stopper, because solvent can't come back out. Five checks take a few minutes and protect every calculation that follows.

Every batch we sell is tested by an independent lab before sale for purity by HPLC and identity by mass spectrometry. The certificate is published in the certificate of analysis library, searchable by the batch number printed on the vial. Our guide on how to read a peptide certificate of analysis walks through the trace and the spectrum.

For any supplier, including us, one more check sits outside the lab. ABN Lookup shows free public records from the Australian Business Register, including whether an ABN is active or cancelled. ^[7]

BAC Water is the default solvent for most research peptides, and dilute acetic acid is the fallback for basic sequences that won't dissolve. Sterile water works for one-off use. The choice rests on the sequence and on how often you will puncture the vial.

Bachem's rule of thumb is to count charged residues first. Basic peptides "may be dissolved in a small amount of an acidic solvent such as acetic acid or trifluoroacetic acid and then diluted", and hydrophobic ones may need an organic solvent such as DMSO. ^[4] Our acetic acid is sold in 3ml vials for that purpose.

The preservative has a record of its own. Studies of a recombinant interleukin-1 receptor antagonist found that reconstitution with 0.9% benzyl alcohol caused more protein aggregation than water, while storage at reduced temperature could limit the effect. ^[2] A 2015 study reported the same pattern for interferon alpha-2a, driven by partial unfolding. ^[8] Both are proteins. No published study we found tests short research peptides the same way, so read the finding as most relevant to the largest molecule in a range, such as the 191-amino-acid HGH. Benzyl alcohol also carries a clinical history: 1982 reports linked benzyl alcohol-preserved fluids to deaths in newborns. ^[9]

Concentration in mg/mL equals the mg of peptide in the vial divided by the mL of solvent added. The table covers every vial size in our range against 1, 2 and 3 mL, the capacity of one BAC Water vial.

Vials labelled in IU follow the same arithmetic in IU/mL. High concentrations can exceed a peptide's solubility, which is why Bachem recommends testing a small amount before committing the whole vial. ^[4]

Worked example: net peptide content. Most synthetic peptides are purified with trifluoroacetic acid and end up as trifluoroacetate salts. ^[10] The counter-ion and residual water weigh something. Bachem defines net peptide content as the peptide share relative to that non-peptidic material and notes that very pure peptides can still show a low figure. ^[1] Take an illustrative 10mg of powder at 80% net peptide content. It holds 8mg of peptide, so 2 mL gives 4 mg/mL, a fifth below the 5 mg/mL the label suggests. Check which basis your certificate reports before you write a concentration on the vial.

Worked example: dilution. To turn 10 mg/mL into 1 mg/mL, use C1 x V1 = C2 x V2. Mix 0.1 mL of stock with 0.9 mL of solvent for 1 mL at 1 mg/mL, a tenfold dilution. Diluting is also the fix when a volume you need is too small to measure well.

On a U-100 insulin syringe, 1 mL spans 100 unit markings, so each marking is 0.01 mL, or 10 microlitres. A 1993 study of U-100 syringes equated 0.5 to 1.0 units with 5 to 10 microlitres and found that volumes below 20 microlitres, 2 markings, carried unacceptably large error. ^[3]

Units on that scale measure volume only. They say nothing about peptide mass until you apply the concentration you calculated. For laboratory work, the practical rule is to choose a solvent volume or dilution that keeps every measured volume well above 20 microlitres.

Reconstitution takes nine steps, and most of the care goes into keeping the vial sterile and the powder dry.

1. Match the batch. Confirm the vial's batch number against its certificate.
2. Warm the sealed vial. Let it reach room temperature before opening. Bachem advises doing this in a desiccator, because peptides are hygroscopic. ^[6]
3. Wipe both stoppers with an alcohol wipe and let them air dry.
4. Draw the solvent. Measure the volume you chose from the concentration table with a sterile syringe.
5. Add it down the glass wall. Let the solvent run slowly down the inside of the vial onto the cake.
6. Swirl or roll gently. Dissolution can take time, occasionally several hours. Brief sonication in a water bath can help, and excessive warming should be avoided. ^[6]
7. Inspect. The solution should be clear with no visible particles.
8. Label. Write compound, batch, solvent, concentration and date on the vial.
9. Store cold. Refrigerate for near-term work, or split into aliquots and freeze for longer storage.

Remove the needle after each transfer. The CDC warns that a needle left in a septum "creates a direct route for microorganisms to enter the vial". ^[5]

The common mistakes fall into three groups: physical stress on the peptide, contamination of the vial and arithmetic errors.

The shaking evidence comes from antibodies, which are large folded proteins, and the damage it describes happens at the liquid surface. Gentle swirling is a cheap precaution for any sequence.

No published stability study covers most research peptides in BAC Water, so any fixed number of weeks is an estimate. What the lab-method sources say is consistent: solutions degrade slowly, and cold, aliquoted storage slows it.

• Bachem advises against storing peptides in solution and says frozen solutions may be kept for a few weeks. ^[6] Its solubility guide says aliquots frozen below minus 20°C mostly stay stable for several months. ^[4] The two pages disagree on duration and agree on method.
• Sequences containing Asn, Gln, Cys, Met or Trp have limited shelf lives in solution. ^[6]
• USP 797, as summarised by the CDC, has an opened vial dated and discarded within 28 days unless the manufacturer states another date. ^[5] That rule governs the sterility of the vial, and it is a sensible ceiling for a refrigerated working vial.

Split anything you won't use soon into aliquots so each one thaws once. Our peptide storage guide covers temperatures, light and labelling in more depth.

Reconstitution changes a compound's form, and its legal status stays the same. Schedule 4 of the Poisons Standard covers substances whose use or supply should be by or on the order of an authorised prescriber. ^[14] The June 2026 instrument commenced on 1 June 2026. ^[14] We checked each compound we stock against it: 13 of our 28 research compounds are Schedule 4, and AOD-9604, BPC-157, CJC-1295, HGH, ipamorelin, TB-500 and tesamorelin also sit in Appendix D clause 5, which makes possession without authority an offence.

For sport, the WADA 2026 Prohibited List took effect on 1 January 2026, and its S0 class names BPC-157 among non-approved substances prohibited at all times. ^[15] Each compound's status is on its product page, and our guide to Australian peptide law explains the schedules.

Reconstitution is simple arithmetic wrapped in sterile technique: mg divided by mL, a clean stopper, a slow pour and a gentle swirl. The weak points are the mass basis on the label, measuring tiny volumes and unsourced shelf-life claims. Check the batch certificate first, write the concentration and date on the vial, and freeze aliquots for anything you'll keep.