AssayIndex
Metabolic and mitochondrial peptides

SS-31 (Elamipretide)

elamipretide · MTP-131 · Bendavia · C32H49N9O5 · monoisotopic 639.3856 Da. The index holds 97 assay reports on this compound across 21 batches from 12 suppliers.

97 reports21 batchesmedian 99.42 %index spec 98.5 %
Section 1

Analytical fingerprint

Hand-authored chemistry. These properties describe the substance and do not change when a record is added.

A tetrapeptide, so the assay is straightforward and the achievable purity is high — SS-31's index median is the highest of any compound tracked here (99.2 %, n over 200). At that level the interesting question stops being purity and becomes counter-ion and water: elamipretide as an acetate salt commonly carries 6–9 % water, which means a nominal 50 mg vial contains materially less than 50 mg of peptide. The purity→mass correction calculator exists mostly for compounds like this one.

Molecular formula
C32H49N9O5
Monoisotopic mass
639.3856Da
Average mass
639.79Da
Residues
4
Nominal retention (RG-2, 30 min)
8.94min
Retention window
0.25min
Counter-ion as usually shipped
acetate
Typical label claims
10 mg · 20 mg · 50 mg
Analytical difficulty (index scale)
0.85 — straightforward
Purity is a defined quantity
YES
Section 2

Representative chromatogram

Drawn from this page's own medians. Not a scan, not an illustration, and not any single report.

030036006900912012 SS-31 (Elamipretide)8.94 min · 99.42 % 9.48 same trace · ×200 vertical expansion, baseline-corrected · main peak off-scale reporting threshold 0.05 % area 05101520253035 Retention time (min) Response (mAU)
Figure 1. A representative SS-31 (Elamipretide) trace on the index reference method RG-2, constructed from this page's own numbers: the main peak carries the index median purity of 99.42 % area at the nominal retention time of 8.94 min, and each impurity peak carries the median area the index has observed for that named species at its characteristic retention offset. It is not a scan of any single report — every individual record's own chromatogram is on its own page. The lower panel is the same trace at a stated vertical expansion, baseline-corrected, so the impurities are visible; the main peak runs off-scale there by design. Baseline noise is seeded from the compound slug.
Section 3

What the index has observed

Arithmetic over the 97 records the index holds. Aggregates on this page are computed over the records the index holds, which are not a random sample of the material on the market. Lots that get tested are lots someone chose to test. Read every figure here as a description of this dataset rather than as an estimate of a population.

Median purity 99.42% n=97
Interquartile range 1.36pp n=97
Minimum 96.77% n=97
Maximum 99.93% n=97
Pass rate vs spec 76.3% n=97
Median recovery vs claim 96.0% n=52
Median water 4.55% n=97
Median |mass error| 2.2ppm n=86
09182792.093.094.095.096.097.098.099.0100.092.00–92.25 %: n=092.25–92.50 %: n=092.50–92.75 %: n=092.75–93.00 %: n=093.00–93.25 %: n=093.25–93.50 %: n=093.50–93.75 %: n=093.75–94.00 %: n=094.00–94.25 %: n=094.25–94.50 %: n=094.50–94.75 %: n=094.75–95.00 %: n=095.00–95.25 %: n=095.25–95.50 %: n=095.50–95.75 %: n=095.75–96.00 %: n=096.00–96.25 %: n=096.25–96.50 %: n=096.50–96.75 %: n=096.75–97.00 %: n=297.00–97.25 %: n=097.25–97.50 %: n=297.50–97.75 %: n=497.75–98.00 %: n=498.00–98.25 %: n=898.25–98.50 %: n=398.50–98.75 %: n=598.75–99.00 %: n=699.00–99.25 %: n=699.25–99.50 %: n=1199.50–99.75 %: n=1599.75–100.00 %: n=31median 99.42 Purity (% area) Reports
Figure 2. Purity distribution across all 97 SS-31 (Elamipretide) records. Dashed line is this compound's median (99.42 %); the solid vertical is the index acceptance specification for the metabolic and mitochondrial peptides class (98.5 %). Domain is fixed at 92–100 % on every purity histogram on this site so that compounds can be compared by eye — a wide distribution here is a hard compound, a narrow one is an easy one, and neither is a statement about the suppliers.
Section 4

By supplier

Suppliers with fewer than two purity records on this compound are omitted from the figure rather than drawn as a line. The full table, including the thin cells, is on the by-supplier page.

96.597.197.798.399.099.6100.2HomopeptideHomopeptide: Q1 99.24, median 99.64, Q3 99.93, n=22n=22FGPFGP: Q1 99.85, median 99.93, Q3 99.93, n=12outlier 99.42outlier 99.54outlier 99.72n=12QSCQSC: Q1 99.93, median 99.93, Q3 99.93, n=11outlier 99.26outlier 99.66n=11JEEPJEEP: Q1 99.04, median 99.39, Q3 99.63, n=11n=11TFCTFC: Q1 98.11, median 98.69, Q3 98.99, n=10n=10QYBQYB: Q1 99.43, median 99.65, Q3 99.87, n=7n=7GL BiochemGL Biochem: Q1 98.10, median 98.18, Q3 98.38, n=6n=6KPKP: Q1 98.47, median 98.81, Q3 99.51, n=6n=6SSASSA: Q1 97.67, median 97.72, Q3 97.85, n=5n=5SGNSGN: Q1 96.86, median 97.07, Q3 97.28, n=4n=4CPCCPC: Q1 97.95, median 98.03, Q3 98.10, n=2n=2 Purity (% area)
Figure 3. SS-31 (Elamipretide) purity by supplier, ordered by coverage. The vertical line is the index acceptance specification. Boxes that overlap are suppliers this dataset cannot separate, and most of them overlap.

Full per-supplier table with n= caveats →

Section 5

Characteristic impurities and degradants

The left three columns are authored chemistry — what this molecule characteristically carries and where it elutes. The right three are what the index has actually reported.

Named speciesΔRT (min, RG-2)Δ mass (Da)Seen inMedian % areaMax % area
C-terminal free acid (+1 Da)+0.20+0.98495%0.081.89
des-Dmt (−193 Da)-0.72-193.11088%0.111.88
[D-Arg1]-epimer-0.18mass-identical79%0.131.34
acetyl adduct (+42 Da)+0.54+42.01178%0.241.31

Degradation pathways

  • C-terminal amide hydrolysis
  • epimerisation at Arg1 under prolonged basic coupling

Full impurity profile, with what each named species implies about the synthesis →

Section 6

Clinical context

Included because it is routinely misapplied. Trial data describes a licensed medicinal product manufactured under a marketing authorisation, and it does not transfer to research-grade material of unknown provenance.

Elamipretide has been studied in primary mitochondrial myopathy and Barth syndrome; results have been mixed and no product is approved.

Section 7

Quarterly coverage

QuarterReportsMedian purityRange
2024-Q10n<3—
2024-Q21n<3—
2024-Q3597.7297.51–97.96
2024-Q41399.8098.87–99.93
2025-Q1698.8198.39–99.69
2025-Q2899.9399.54–99.93
2025-Q31999.8897.87–99.93
2025-Q42499.0996.77–99.93
2026-Q10n<3—
2026-Q21299.6698.98–99.93
2026-Q3998.6697.71–99.93

Quarter-by-quarter detail →

Section 8

Most recent records

The 25 most recent SS-31 (Elamipretide) records of 97.
ReportSupplierLotLabQuarterPurity %Water %Recovery %ProvenanceFlagsResult
AX-2026-042067TFCTFC-2604-Y7472Kestrel2026-Q398.664.44—Supplier-supplied1MARGINAL
AX-2026-042068TFCTFC-2604-Y7472Medutest2026-Q398.713.6392.9Supplier-supplied2MARGINAL
AX-2026-042069TFCTFC-2604-Y7472Janoshik2026-Q398.163.65—Supplier-supplied2FAIL
AX-2026-042070TFCTFC-2604-Y7472PeptideMeter2026-Q398.093.6097.9Supplier-supplied1FAIL
AX-2026-042072TFCTFC-2604-Y7472VendorInvestigate2026-Q397.883.4789.5Buyer-sourced2FAIL
AX-2026-042236HomopeptideHOMO-2604-D1599PeptideMeter2026-Q399.612.79—Supplier-supplied0PASS
AX-2026-041951TFCTFC-2607-R4363Medutest2026-Q399.565.16—Buyer-sourced0PASS
AX-2026-042071TFCTFC-2604-Y7472PeptideMeter2026-Q397.713.4793.0Laboratory-retained2FAIL
AX-2026-042237HomopeptideHOMO-2604-D1599Janoshik2026-Q399.933.12101.9Supplier-supplied0PASS
AX-2026-041464QYBQYB-2512-H5402Janoshik2026-Q299.514.72—Supplier-supplied1MARGINAL
AX-2026-041590QSCQSC-2605-E6873Janoshik2026-Q299.262.5892.4Supplier-supplied0PASS
AX-2026-041463QYBQYB-2512-H5402Janoshik2026-Q299.655.1891.5Supplier-supplied0PASS
AX-2026-041466QYBQYB-2512-H5402Janoshik2026-Q299.935.07—Supplier-supplied0PASS
AX-2026-041778FGPFGP-2601-R1916VendorInvestigate2026-Q299.424.0590.3Buyer-sourced0PASS
AX-2026-041775FGPFGP-2601-R1916Janoshik2026-Q299.725.0696.7Supplier-supplied0PASS
AX-2026-041776FGPFGP-2601-R1916Medutest2026-Q299.933.97—Supplier-supplied0PASS
AX-2026-041467QYBQYB-2512-H5402PeptideMeter2026-Q299.865.21—Supplier-supplied0PASS
AX-2026-041591QSCQSC-2605-E6873Janoshik2026-Q299.662.08102.9Supplier-supplied1MARGINAL
AX-2026-041465QYBQYB-2512-H5402PeptideMeter2026-Q299.355.44—Supplier-supplied0PASS
AX-2026-041462QYBQYB-2512-H5402Medutest2026-Q298.984.7398.6Supplier-supplied1MARGINAL
AX-2026-041777FGPFGP-2601-R1916PeptideMeter2026-Q299.934.09—Supplier-supplied1MARGINAL
AX-2026-041875JEEPJEEP-2511-B3061Janoshik2025-Q499.105.11—Supplier-supplied0PASS
AX-2025-019665HomopeptideHOMO-2507-B2039Janoshik2025-Q499.425.99107.1Supplier-supplied0PASS
AX-2025-019051JEEPJEEP-2511-B3061Janoshik2025-Q499.395.16—Laboratory-retained2MARGINAL
AX-2025-019049JEEPJEEP-2511-B3061Janoshik2025-Q499.935.29—Supplier-supplied0PASS