Where to buy SS-31 Peptide: sizes, price per mg and how to verify the lot

What "ss-31 peptide" names, and what it does not

SS-31 is a four-residue synthetic peptide, D-arginine, 2',6'-dimethyltyrosine, lysine and phenylalanine, with an amidated C-terminus; formula C32H49N9O5, average mass 639.8 Da. The Szeto-Schiller laboratory named it SS-31; Stealth BioTherapeutics developed it as MTP-131 and then elamipretide, and Bendavia was an early trade name. The papers cited at the foot of this page describe how it associates with mitochondrial membranes in cell and animal models. Listings write SS-31, ss31 peptide and elamipretide; those are one molecule, and a certificate may use any of the names without that being a chemical difference.

What is a difference is the approved product. In September 2025 the FDA granted accelerated approval to Forzinity, elamipretide hydrochloride, for a rare inherited disorder; that product is manufactured under an approval to a specification and released against it. A research vial of SS-31 is a synthetic peptide with the same sequence sold as laboratory material and standing on its lot certificate, usually as the acetate rather than the hydrochloride. No equivalence is claimed here and none can be shown by a certificate, which measures a lot and not a manufacturing process.

The two unnatural features, the D-arginine and the dimethyltyrosine, are where cheap imitations live. Replace the dimethyltyrosine with ordinary tyrosine and the peptide is 28 Da lighter and much cheaper to make; make the arginine L instead of D and the mass does not change at all. The first is caught by any mass spectrometer, the second only by chiral analysis or a reference comparison. This page describes the material, not any use.

The reference point for identity is public. PubChem lists Elamipretide as CID 11764719 with molecular formula C32H49N9O5, an average molecular weight of 639.8 Da and a monoisotopic mass of 639.386 Da. Those are the numbers a mass spectrometer is checked against, and the number a certificate must print beside the observed mass.

In plain terms: A man-made four-building-block peptide that gathers in mitochondria, also published as elamipretide. No approved product. SS-31 and elamipretide are two names for the same peptide, and certificates may use either; that is a naming difference, not a chemical one.

SS-31 for sale: sizes and price per mg

LabFirst lists SS-31 in 2 sizes (10mg, 50mg) from $59 to $209, priced per vial with the per-mg figure beside it so sizes can be compared without arithmetic. Per mg, the 10mg vial is the cheapest today at $5.90 and the 10mg the dearest at $5.90, which is the reverse of the usual shape; the table below is the arithmetic, and the per-mg column, not the vial price, is the one to compare.

The volume tiers are per size, not per basket: ten vials of one size take 10% off that line and twenty take 15%, and mixed sizes do not combine. Shipping is a flat $15 on orders under $200 and free from $200, within the United States only, with same-day dispatch on orders placed before 12 PM Pacific on a business day. The cost per mg tool runs the same comparison across any two listings, ours or anyone else's.

Four residues, two of them costly unnatural building blocks, make SS-31 a mid-priced synthesis per milligram, more than a tripeptide and less than a long chain. LabFirst lists 10 mg and 50 mg vials and the per-milligram figure falls sharply between them, the vial, the fill and the laboratory run being fixed costs spread over five times the mass. A laboratory qualifying a lot buys the 10 mg vial once and reads its certificate for the dimethyltyrosine mass before buying larger.

The price signal is the imitation. The tyrosine substitute and the all-L version are cheaper to make, and a listing far under the market is often one of them; the certificate's observed mass catches the first and nothing on most certificates catches the second. A steady price from a seller whose lots are tested outside is worth more than a discount from one whose are not. The only discounts on this page are the volume tiers, per size and unchanged month to month, and the lot on the vial is whatever the certificate index says on the day.

The certificate a SS-31 lot must carry

Three tests answer three different questions, and a certificate of analysis for SS-31 is only complete when it carries all three for the exact lot on the vial. Identity is settled by mass spectrometry, and the number to look for on a SS-31 certificate is 639.386 Da monoisotopic (or 639.8 Da average, if the laboratory reports the deconvoluted average mass). The observed mass should sit within the instrument's stated tolerance of that figure, and the certificate should print both the theoretical and the observed value, not just a tick.

Purity is a separate question, answered by HPLC: how much of what came off the column was the compound. The figure is only interpretable with its method beside it (column, gradient, detection wavelength) and a date, which is what ICH Q2(R2) means when it asks that an analytical procedure be shown fit for its purpose. A percentage with no method and no date is a number somebody typed, and a certificate that carries every test but for a different lot number than the vial is the most common failure of all and the easiest to catch. Net content is the third test and the one most often missing: the milligrams of SS-31 actually in the vial, measured, against the size printed on the label.

Identity is the observed mass against 639.386 Da monoisotopic (639.8 Da average), seen in electrospray as m/z 640.4 for the singly charged ion and 320.7 for the doubly charged, with the theoretical and observed values both printed. A mass near 611.4 is the tyrosine-for-dimethyltyrosine substitute, a cheaper and different peptide. A matching mass does not settle the D-arginine; a laboratory that ran a chiral amino acid analysis or an HPLC comparison against a reference standard says so, and for a routine research lot the exact mass with a clean chromatogram from a named outside laboratory is the practical standard.

Purity by HPLC on a tetrapeptide is straightforward and the chromatogram should still be shown with its conditions, because the des-methyl substitute and a deletion sequence are the impurities that matter and both resolve from the main peak on a proper method. Net content is the third line: SS-31 is supplied as an acetate or, from some factories, a trifluoroacetate, and with an arginine and a lysine it holds two counter-ions, so the gap between milligrams of powder and milligrams of peptide can be a fifth on a 10 mg vial. Quantitative HPLC or amino acid analysis tells you which the label counts, and the salt belongs beside that figure.

Where to buy SS-31: five checks before you order from anyone

Every seller of ss-31 peptide says "third-party tested". The phrase costs nothing. These five checks take about four minutes per listing and separate a tested lot from a tested-sounding one.

1. The lot on the vial is the lot on the certificate. Read the printed lot number, then open the certificate and match it. A certificate for "SS-31" with no lot, or a lot that does not match, describes some other vial.
2. The laboratory is named and has its own lookup. The report should come from a laboratory the seller does not own, with a search code you can enter on the laboratory's own site. LabFirst lots are tested by Freedom Diagnostics and looked up by accession number; anything that can only be verified on the seller's own page has not been verified.
3. The theoretical mass is printed, and it is the right one. For SS-31 that is 639.386 Da monoisotopic; a certificate that prints a different figure has either measured a different molecule or copied a template.
4. Purity has a method and a date. An HPLC percentage should name the method and the run date. A figure that reads "99%+" with neither, or one date reused across every product a seller lists, is decoration.
5. Net content is stated in milligrams. The label size is a claim; the certificate's net content is the measurement. If the certificate has no net content line, the purity figure describes the powder, not the vial, and the price per mg you calculated is fiction.

How listings for SS-31 specifically mislead:

• "Same as elamipretide" meaning same as the approved product. Same molecule, different thing: Forzinity is made under an approval to a specification; a research vial has a lot certificate and nothing else.
• A certificate with a mass near 611 Da. That is the tyrosine-for-dimethyltyrosine substitute, 28 Da lighter, cheaper and a different compound; the purity figure beside it describes the wrong peptide.
• A price far below the market. The all-L imitation weighs exactly the same and mass spectrometry cannot see it; only chiral analysis or a reference comparison can, and cheap lots have rarely had either.
• A 10 mg label with no counter-ion and no net content line. Two counter-ions on a 640 Da peptide are a large share of the powder; without the content line the milligrams are unknown.

How to verify a LabFirst SS-31 lot

The SS-31 sizes in stock today carry lot LF-2608-26. Lot LF-2608-26 is at Freedom Diagnostics on accession FD-2026-05716 for identity, purity and net content. Until the report is attached the product page says "pending verification" against that lot and makes no purity claim; the price stands and the report goes live the day it arrives, on the page, at /coa/, and inside the receipt and packing slip for every order of that lot.

Verification runs through the laboratory, not through us. Open the certificate index, find the lot, and use the accession number on the Freedom Diagnostics lookup page; the report you see there is the laboratory's copy, not ours. Each lot also carries a Finnrick verify link, and every receipt and packing slip states that a customer may submit a sealed vial to Finnrick's free testing programme with the order as proof of purchase, so the brand's public record is built from vials we did not choose.

The product page reads the live stock feed on load (stock, lot and certificate state for every size), so what you see when you order is what ships. The lot is printed on the label and encoded in the QR patch on its right-hand side; scanning it opens that lot's record.

Storage and shipping for SS-31

SS-31 is a robust peptide: no cysteine, no methionine, no asparagine or glutamine, a D-residue at the N-terminus and an unnatural residue beside it, so the usual chemical routes to degradation do not apply. Lyophilised and sealed at 2 to 8 C out of light it keeps for the full shelf period on the certificate, and in solution it outlasts most of the catalogue, though a laboratory still dates its solutions and keeps its own record because robust is a comparison rather than a number. Its one weakness is water: as a salt with two counter-ions it takes moisture from humid air once opened, so open a vial once, for its purpose, and never re-seal one for storage.

Orders ship within the United States, flat $15 under $200 and free above it, same day when placed before 12 PM Pacific on a business day, and the shipping page states the cutoff, the carriers and what is and is not promised.

The record a laboratory keeps on arrival is what makes the certificate usable later, and it is short:

• the lot number as printed on the vial, and the certificate's accession or search code beside it;
• the date received and the condition of the seal;
• the storage location and temperature it went into;
• the number of vials, and later the date each one was opened and by whom.

A SS-31 vial with that record behind it can be traced from the bench to the laboratory report in one step; without it, the certificate is a document about a vial that can no longer be identified.

Regulatory status, and what this page is not

Elamipretide is the active ingredient of an approved medicine: on 19 September 2025 the FDA granted accelerated approval to Forzinity (elamipretide hydrochloride) from Stealth BioTherapeutics for a rare inherited disorder, the approval letter cited below. That approval belongs to that product and its manufacturing and confers nothing on a research vial: the SS-31 sold here is not made under it, is not tested to its specification, is normally the acetate rather than the hydrochloride, and is offered as laboratory material only, with no claim that it is equivalent to, as pure as, or a substitute for any medicine. There is no USP monograph for the bulk peptide that a research lot could claim to meet.

FOR LABORATORY AND IN-VITRO RESEARCH USE ONLY. NOT FOR HUMAN OR ANIMAL CONSUMPTION. LabFirst sells SS-31 to laboratories and researchers as material for in-vitro work, gives no guidance on use, and ships only against that understanding. Nothing on this page or on the product page describes preparing or administering anything.

What is SS-31 studied for?

Published research on SS-31 investigates the areas below — which is a different question from what SS-31 will do for anyone, a claim about a living system that nothing on this site is sold for.

What it is. A man-made four-building-block peptide that gathers in mitochondria, also published as elamipretide.

What the research looks at. Animal and clinical-stage research on mitochondria and on cardiolipin.

How it is thought to work. Described in the research as sticking to cardiolipin, a fat molecule in the inner membrane of mitochondria. Its alternating pattern of bulky and positively charged building blocks is the feature associated with it ending up there.

What is not established. No approved product. SS-31 and elamipretide are two names for the same peptide, and certificates may use either; that is a naming difference, not a chemical one.

The full record, including the certificate for the lot in stock, is on the SS-31 product page.

Common questions

Sources

• PubChem, Elamipretide, CID 11764719. Public record for the molecular formula (C32H49N9O5), average molecular weight (639.8 Da) and monoisotopic mass (639.386 Da) quoted here as the identity reference.
• Birk and colleagues, The mitochondrial-targeted compound SS-31 re-energizes ischemic mitochondria by interacting with cardiolipin, Journal of the American Society of Nephrology 2013. Primary description of the compound in the literature; supports the class and naming stated here, not any use.
• Mitchell and colleagues, The mitochondria-targeted peptide SS-31 binds lipid bilayers and modulates surface electrostatics, Journal of Biological Chemistry 2020. Primary description of the compound in the literature; supports the class and naming stated here, not any use.
• The cardiolipin-binding peptide elamipretide mitigates fragmentation of cristae networks following cardiac ischemia reperfusion in rats, Communications Biology 2020. Primary description of the compound in the literature; supports the class and naming stated here, not any use.
• FDA, NDA 215244 accelerated approval letter, Forzinity (elamipretide), 19 September 2025 2025-09-19. The approval letter for the elamipretide drug product; cited to show that the approved medicine and the research peptide are different things with different evidence behind them.
• ICH Q2(R2), Validation of Analytical Procedures (2023) 2023-11. Why a purity figure is only interpretable with its method, and what "fit for purpose" means for the HPLC and mass spectrometry results a certificate reports.
• Freedom Diagnostics, certificate lookup by accession number. The laboratory-side lookup a LabFirst lot is verified on; the report there is the laboratory copy, not ours.
• Finnrick, verify a vendor or lot. Independent verification page linked from every LabFirst lot; customers may submit sealed vials with their order as proof of purchase.