Catalogue / Semaglutide
Semaglutide
Also written as GLP-1 analogue.
A 31 residue GLP-1 analogue with an AIB substitution at position 8 and a C18 diacid chain attached through a gamma-Glu-2xOEG linker on lysine 26.
| Molecular formula | C187H291N45O59 |
| Average mass | 4113.58 Da |
| Monoisotopic mass | 4111.1154 Da |
| Class | Incretin analogues |
| Determination | Blind identification, GLP-1 class |
| Price | 468 USD |
Computed at build time from the composition shown on this page, not transcribed from a supplier datasheet.
Semaglutide has an average molecular weight of 4113.58 daltons and a monoisotopic mass of 4111.1154 daltons. Identity is confirmed by matching the measured deconvoluted mass to that figure, and purity is reported separately by reversed-phase chromatography at 214 nm. The two numbers answer different questions and neither substitutes for the other.
| Charge | m/z |
|---|---|
| [M+3H]3+ | 1371.379 |
| [M+4H]4+ | 1028.786 |
| [M+5H]5+ | 823.23 |
These are the ions an electrospray source is expected to produce for a neutral mass of 4111.1154 daltons, computed from the monoisotopic mass and the proton mass. They are what a raw spectrum should show before deconvolution.
A report that gives only a deconvoluted mass without the charge states it was derived from cannot be checked. Deconvolution is a calculation, and a calculation whose inputs are not shown is an assertion.
| The class is crowded. Several analogues in circulation differ from each other by a single residue or by linker length, and none of those differences is visible on a retention time alone. |
| The fatty acid side chain makes the molecule surface-active. It adsorbs to glass and to polypropylene, so a low result is as likely to be a handling artefact as a real content shortfall unless recovery is demonstrated. |
| Deconvolution of the multiply charged envelope must be reported, not just a single charge state, because an isotope-envelope assignment on one charge state can be off by a whole dalton. |
Every compound fails in its own way. A generic peptide method applied without regard to these specifics produces a number that looks like a result and is not one.
Long-acting GLP-1 and dual agonists carrying a fatty acid chain on a lysine side chain. The class is chemically crowded, and analogues differ by a single substitution or a linker length.
LC-MS on the multiply charged envelope with deconvolution to the neutral mass, because analogues in this class co-elute closely and a retention-time match cannot separate them. Purity by RP-HPLC at 214 nm with a shallow acetonitrile gradient.
Where the delivered milligram figure matters rather than the percentage, net peptide content by combustion analysis and water by Karl Fischer are added, and the certificate carries a closed mass balance instead of a single purity number.
| LC-MS identity | Measured mass |
| RP-HPLC purity | Area at 214 nm |
| Net peptide content | Milligrams |
| Water content | Karl Fischer |
| Counter-ion | Ion chromatography |
| Bacterial endotoxins | USP <85> |
What is the molecular weight of Semaglutide?
The average molecular weight is 4113.58 daltons and the monoisotopic mass is 4111.1154 daltons, computed from the molecular formula C187H291N45O59 shown on this page. Both figures are calculated rather than transcribed, so they can be checked against the stated composition.
How is Semaglutide tested for purity and identity?
LC-MS on the multiply charged envelope with deconvolution to the neutral mass, because analogues in this class co-elute closely and a retention-time match cannot separate them. Purity by RP-HPLC at 214 nm with a shallow acetonitrile gradient. Purity describes the chromatographable fraction only and is not the same quantity as the peptide mass delivered per vial.
What goes wrong when Semaglutide is analysed?
The class is crowded. Several analogues in circulation differ from each other by a single residue or by linker length, and none of those differences is visible on a retention time alone.
What does Semaglutide analysis cost at ANALYTON?
Blind identification, GLP-1 class is priced at 468 US dollars, covering the determinations described on this page. Content, safety and elemental determinations are ordered alongside and are priced separately on the price list.
Other compounds in this class
Updated 2026-09-01. Masses computed at build, not transcribed.