Guide
Semaglutide reconstitution: the numbers for the bench
Semaglutide's numbers in one place: mass, the C18 chain that extends its half-life, vial sizes, concentration table and what its report should show.
Published September 4, 2026
Semaglutide is an acylated analog of human GLP-1(7-37). The acylation is the interesting part.
| Peptide | Vial sizes | From |
|---|---|---|
| Semaglutide | 5mg, 10mg, 20mg, 30mg | $42.99 CAD |
| Tirzepatide | 5mg, 10mg, 15mg, 20mg, 30mg, 40mg, 50mg, 60mg | $42.99 CAD |
| Cagrilintide | 5mg, 10mg, 20mg | $60.99 CAD |
Free shipping across Canada. Every vial ships with a QR code linking to its own batch lab report. See all peptides
Identity
| Formula | C187H291N45O59 |
| Molecular weight | 4113.58 g/mol |
| CAS | 910463-68-2 |
| Receptor | GLP-1 |
| Vial sizes we sell | 5, 10, 20, 30 mg |
The chain that changes the timescale
Native GLP-1 is cleared in minutes. Semaglutide carries a C18 fatty-diacid chain attached to the backbone, and that chain binds albumin, the most abundant protein in blood. A molecule travelling with albumin is not filtered the way a free peptide is, so its half-life in research models is measured in days.
That is also most of why the mass is 4,114 g/mol rather than the roughly 3,300 of the unmodified hormone. The chain and its linker are a substantial fraction of the molecule.
Concentration
| Vial | 1 mL | 2 mL | 3 mL | 5 mL |
|---|---|---|---|---|
| 5 mg | 5 mg/mL1.22 mM | 2.5 mg/mL0.608 mM | 1.67 mg/mL0.405 mM | 1 mg/mL0.243 mM |
| 10 mg | 10 mg/mL2.43 mM | 5 mg/mL1.22 mM | 3.33 mg/mL0.81 mM | 2 mg/mL0.486 mM |
| 20 mg | 20 mg/mL4.86 mM | 10 mg/mL2.43 mM | 6.67 mg/mL1.62 mM | 4 mg/mL0.972 mM |
| 30 mg | 30 mg/mL7.29 mM | 15 mg/mL3.65 mM | 10 mg/mL2.43 mM | 6 mg/mL1.46 mM |
Semaglutide vial sizes we sell, at four diluent volumes. Molarity uses 4113.58 g/mol. Other volumes
A 5 mg vial is about 1.22 micromoles. The semaglutide calculator has all four sizes preset.
Handling
Bacteriostatic water down the glass wall, swirl, no shaking. Freezer for the dry powder, fridge once reconstituted, and split into aliquots rather than refreezing. The reconstitution guide covers the technique and the storage guide the temperatures.
Checking the report
An observed mass near 4113.58, purity at 99% or higher by HPLC, the batch number, and the lab's name. Semaglutide is 618 g/mol lighter than retatrutide and 700 lighter than tirzepatide, so there is no room for confusion between them on a mass-spec line.
Look up any batch by code, or scan the vial. Before you order, the Lab Reports tab on the product page sends you the latest batch's report by email.
Where it sits among the three
One receptor. Semaglutide vs tirzepatide vs retatrutide compares all three by receptor count, sequence and mass.
Every semaglutide vial from pepuro ships free, from our Calgary, Toronto and Vancouver distribution centers, the same business day your e-Transfer clears, with a QR code on the vial that opens its independent, third-party lab report.
For research use only. Not for human or animal consumption.
Frequently asked questions
What is the molecular weight of semaglutide?
+
4113.58 g/mol, formula C187H291N45O59. It is the lightest of the three incretin peptides we carry.
How much water do I add to a 5 mg semaglutide vial?
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1 mL gives 5 mg/mL, 2 mL gives 2.5 mg/mL, 5 mL gives 1 mg/mL. The vial holds 5 mg whichever volume you choose.
What does the fatty acid chain on semaglutide do?
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The C18 fatty-diacid chain binds albumin, which keeps the peptide in circulation far longer than the unmodified hormone. It is the reason the molecule lasts days rather than minutes in research models.
Which semaglutide vial sizes are available?
+
5, 10, 20 and 30 mg.
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