SS-31 Research Peptide: Identity, CAS & COA

SS-31 (elamipretide / MTP-131) is a Szeto-Schiller tetrapeptide (CAS 736992-21-5). Formula/mass anchors and lot COA purity panels. Research use only.

Last reviewed 21 September 2026 · For research use only

SS-31 is a synthetic four-residue Szeto-Schiller tetrapeptide, also listed under the aliases elamipretide and MTP-131. It is a discrete research material with its own CAS, formula, molar mass, sequence, and lot documentation — not a catalogue nickname for every related listing, and not a synonym for unrelated research SKUs or consumer therapy products.

If you found “ss-31,” “ss31,” “elamipretide,” “mtp-131,” “ss-31 research peptide,” “ss-31 coa,” or “ss-31 third party tested” in a listing, the useful questions are which registry fields the seller claims, whether the certificate matches those anchors, and how the vial lot is documented. Aliases vary; registry fields and certificates do not.

This page covers Peptide Foundry’s published identity anchors, the purity panels a research buyer should demand, a worked third-party lot for the live 10 mg option, and short naming literacy — then soft-handoffs to the SS-31 research product page. Research use only.

Key points

• SS-31 = synthetic four-residue Szeto-Schiller tetrapeptide (also listed as elamipretide / MTP-131); supplied as lyophilized research material. Listing aliases = naming literacy only — not a therapy claim.
• Peptide Foundry catalog anchors (live PDP): CAS 736992-21-5, formula C₃₂H₄₉N₉O₅, molar mass 639.8 g/mol, PubChem CID 11764719 — match certificate fields to these claims (parent peptide; salt/counterion not specified on certificate).
• SKU PF-SS-31; live size option 10 mg lyophilized — match each vial to its own lot certificate (current worked example = FO676 / Freedom Diagnostics).
• Demand a lot-matched COA: HPLC purity (method when stated), identity method, named laboratory, preferably portal verify; “third-party tested” / “high purity” without lot + named lab is unfinished.
• Research use only — not for human or veterinary use; not a mitochondrial-therapy, cardioprotection, anti-aging, exercise-performance, wellness, or consumer drug product.

What is SS-31?

SS-31 is a synthetic four-residue peptide in the Szeto-Schiller family. Residue count is four. The research material on this page is that defined tetrapeptide class with the published registry anchors below — not a crude tissue extract and not a brand stack.

The live Peptide Foundry product page publishes the sequence D-Arg–2′,6′-dimethylTyr–Lys–Phe–NH₂ (amidated C-terminus; D-arginine residue). That sequence is identity and naming literacy matching the catalog chemistry block — not a therapy claim and not a reason to treat every listing alias as interchangeable.

A short class note anchors naming only: published laboratory literature characterizes SS-31 as a research tool compound examined in cardiolipin-containing membrane preparations in preclinical and in-vitro models — literature-class context, not a catalogue mechanism claim and not product-use framing.

Physical form on research listings is lyophilized solid. Peptide Foundry’s catalog documents lyophilized powder under SKU PF-SS-31 at a 10 mg size option. Appearance is a handling observation — not a purity proof and not a substitute for HPLC or identity data.

Market aliases include SS-31, SS31, elamipretide, MTP-131, and Szeto-Schiller. Aliases help search and inventory. They are not identity proof until CAS, formula, molar mass, sequence framing, and a lot-matched certificate agree — and they are not a drug- or therapy-as-benefit claim. The live Peptide Foundry PDP notes that formula, CAS, and mass identify the parent peptide and do not establish counterion or salt composition; this page follows that publication set and does not invent a salt form or alternate CAS.

Chemical identity anchors

Peptide Foundry publishes a fixed identity set for single-vial SS-31. The values below match the live catalog chemistry table at the time of writing. Confirm against the current product page if a lot or chemistry block rotates after publish.

Naming and class

Class: synthetic four-residue Szeto-Schiller tetrapeptide; research tool compound (literature class). Listing aliases: elamipretide / MTP-131 / Szeto-Schiller (naming only — not therapy-as-benefit). SKU PF-SS-31 (variation PF-SS-31-10MG); size option on the live listing at publish time: 10 mg lyophilized.

CAS, formula, and molar mass

Market pages sometimes round mass differently or recycle CAS strings across unrelated aliases. The practical rule is: match the vendor’s stated CAS + formula + molar mass + sequence framing to the lot COA, then prefer orthogonal identity (MS / HPLC) over the nickname alone.

What an SS-31 COA should show

A certificate of analysis is stronger when it is lot-specific, names the laboratory, states methods, and can be checked outside the supplier’s own site. For the full verification workflow — batch match, named lab, HPLC versus identity, biosafety panels, portal codes — see How to read a research-peptide COA.

Minimum research COA fields

• A lot / batch ID that matches the vial character for character
• Test or report date(s) and a named laboratory
• HPLC purity with method when stated (for example HPLC-UV)
• An identity method (MS and/or HPLC)
• Product name / composition consistent with the label and the vendor’s published anchors

“Third-party tested,” “high purity SS-31,” or “99%+” without a named lab and a lot number is an unfinished claim. A pretty PDF that cannot be tied to the vial in hand is documentation theater.

Stronger panels (when claimed)

When a full QC panel is present — the pattern on current Peptide Foundry Freedom Diagnostics–tested lots — read these as separate analytical results:

• Mass-spectrometry identity confirmation (for example LC-MS)
• Net peptide content versus labeled mass when reported
• Heavy metals by ICP-MS against stated limits
• Microbial DNA / sterility panels (for example PCR)
• Endotoxin (for example USP <85> / LAL)

These describe composition and contamination panels for research documentation — not a safety-for-human-use claim, and not a substitute for identity or purity.

Worked example — lot FO676 (10 mg)

As published on the current Peptide Foundry SS-31 listing at the time of writing for the 10 mg option:

Cite those figures as Peptide Foundry–published transparency for this lot — not a universal industry floor. Re-verify against the live product panel if the lot rotates. Downloadable COA PDF/PNG appear on the live listing; verify independently at the Freedom Diagnostics portal (freedomdiagnosticstesting.com) with the published access code.

Three steps that travel with any lot, not just FO676:

1. Match the lot number on the vial to the lot on the certificate.
2. Confirm CAS, formula, and labeled mass against the certificate and the product label.
3. Verify the access code on the issuing laboratory’s own portal (Freedom Diagnostics for FO676: access code Pept2609040431) — not only by opening a PDF hosted by the supplier.

Portable vendor criteria beyond a single SKU: USA research-peptide vendor criteria.

Related research peers (soft handoffs)

Research catalogues sometimes co-browse related materials beside SS-31 listings. Co-browsing is inventory adjacency — not a synonym set and not a stack protocol.

• MOTS-c research identity — live chemical/catalog sibling; match each vial to its own CAS, formula, and lot certificate. Soft identity peer only — never a stack recommendation.
• NAD+ research identity — live catalog sibling often co-browsed; chemical/catalog literacy only.
• Epithalon research identity — optional soft catalog peer; chemical/catalog literacy only.
• How to read a research-peptide COA and USA research-peptide vendor criteria — same trust workflow.
• Lyophilized peptide reconstitution — general lab diluent literacy without SS-31 schedules.

Match each vial to its own registry fields and lot certificate. Catalogue adjacency is literacy — not a stack recommendation.

Tool-compound / naming literacy (preclinical framing only)

Mechanism language here classifies experimental systems in published literature only. It does not establish catalogue-product outcomes in people, and it does not convert a citation into a certificate.

Therapeutic-adjacent titles in wider SERPs sit outside this RUO identity page and are not summarized as product use. Identity remains an analytical question answered by CAS, formula, sequence framing, and the lot COA.

Storage and lab handling (lyophilized)

Standard laboratory practice for lyophilized synthetic peptides applies:

• Storage. Sealed vials at −20°C, protected from light and moisture. Lyophilized material is substantially more stable than solution.
• Temperature excursions. Brief ambient exposure in transit is normal for lyophilized material. Return vials to −20°C on arrival.
• Freeze–thaw. Minimize repeated freeze–thaw.
• Traceability. Keep the lot number with the material — lot number ties a vial back to its certificate.

The live FO676 certificate does not report a stability study, storage temperature, or validated shelf life after preparation — this page does not invent one. Assay-specific handling follows your institution’s SOPs. This page does not publish personal reconstitution schedules or solution-use protocols for SS-31. General diluent literacy (without compound-specific schedules): Lyophilized peptide reconstitution.

Common questions

For the current lot certificate and product specifications, see the SS-31 research product page. Related library reading: How to read a research-peptide COA, USA research-peptide vendor criteria, Lyophilized peptide reconstitution, MOTS-c research identity, NAD+ research identity, and Epithalon research identity.

Research use only. Nothing on this page describes or implies use in humans or animals. Tool-compound mentions of cardiolipin-containing membrane preparations refer only to preclinical and in-vitro literature contexts and are not product outcomes.