Lab tools

Peptide identity index

The peptide identity index tells you whether two names used for research peptides refer to the same molecule. Look up a catalog name, a CAS number, or an alias. Compare a second name when a vial, a paper, or a COA uses a different label.

Mass values computed from sequence are for checking an HPLC-MS report. This page does not calculate reconstitution volumes or human doses. Pair it with a lot-linked Certificate of Analysis and the 12-point COA audit.

Compound A

Semaglutide

910463-68-2

Compound B

Tirzepatide

2023788-19-2

Observed mass from a COA

Not the same molecule

GLP-1 analog versus a GIP/GLP-1 dual agonist. Different sequences.

Peptide

Semaglutide

View specs

CAS: 910463-68-2
Formula: C187H291N45O59
Catalog mass: 4,113.58 Da
Sequence avg: Not computed
Monoisotopic: Not computed
Sequence: H-His-Aib-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys(AEEA-AEEA-γ-Glu-C18 diacid)-Glu-Phe-Ile-Ala-Trp-Leu-Val-Arg-Gly-Arg-Gly-OH

Sequence notation is too modified to compute ions here. Use the catalog mass and the COA report together.

COA documents PubChem CAS search

Often confused with

Tirzepatide

Peptide

Tirzepatide

View specs

CAS: 2023788-19-2
Formula: C225H348N48O68
Catalog mass: 4,813.45 Da
Sequence avg: Not computed
Monoisotopic: Not computed
Sequence: Y-Aib-EGTFTSDYSI-Aib-LDKIAQK(AEEA-AEEA-γ-Glu-C20 diacid)AFVQWLIAGGPSSGAPPPS-NH2

Sequence notation is too modified to compute ions here. Use the catalog mass and the COA report together.

COA documents PubChem CID 156588324

Often confused with

How the index decides

Catalog CAS, formula, and sequence come from Tetrava lot identity tables. Monoisotopic mass and expected ions are calculated only when the sequence parses as standard residues plus common caps (acetyl, amide, Aib, Nle, pGlu). Heavily modified GLP-1 analogs stay as catalog text.

TB-500 is the main trap. Supplier tables often reuse the CAS and 4,963 Da mass of full-length thymosin beta-4 on a vial whose sequence is Ac-LKKTETQ. This index splits those identities on purpose.

Research use only. Not for human or veterinary consumption.