AssayIndex
Tissue-repair and immunomodulatory peptides

LL-37

human cathelicidin LL-37 · hCAP-18 (104-140) · C205H340N60O53 · monoisotopic 4490.4265 Da. The index holds 36 assay reports on this compound across 4 batches from 4 suppliers.

36 reports4 batchesmedian 98.61 %index spec 96.5 %
Section 1

Analytical fingerprint

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

LL-37 is strongly cationic (net +6) and adsorbs to plastic. The index has three reports where sequential injections from the same polypropylene vial showed declining peak area, which is an artefact of the container and not the lot; sample-prep detail is mandatory and the record page prints the vial material. Purity is the lowest of any short-to-medium peptide tracked here (median 96.8 %) because the synthesis is long and the crude is difficult to resolve preparatively.

Molecular formula
C205H340N60O53
Monoisotopic mass
4490.4265Da
Average mass
4493.33Da
Residues
37
Nominal retention (RG-2, 30 min)
14.36min
Retention window
0.40min
Counter-ion as usually shipped
TFA
Typical label claims
1 mg · 5 mg · 10 mg
Analytical difficulty (index scale)
1.30 — moderate
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.

01854370955637418 LL-3714.36 min · 98.61 % 12.6817.2115.20 same trace · ×100 vertical expansion, baseline-corrected · main peak off-scale reporting threshold 0.05 % area 05101520253035 Retention time (min) Response (mAU)
Figure 1. A representative LL-37 trace on the index reference method RG-2, constructed from this page's own numbers: the main peak carries the index median purity of 98.61 % area at the nominal retention time of 14.36 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 36 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 98.61% n=36
Interquartile range 0.99pp n=36
Minimum 97.51% n=36
Maximum 99.93% n=36
Pass rate vs spec 100.0% n=36
Median recovery vs claim 98.6% n=23
Median water 4.06% n=36
Median |mass error| 2.4ppm n=31
024692.093.094.095.096.097.098.099.0100.092.00–92.25 %: 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=097.00–97.25 %: n=097.25–97.50 %: n=097.50–97.75 %: n=297.75–98.00 %: n=498.00–98.25 %: n=498.25–98.50 %: n=798.50–98.75 %: n=298.75–99.00 %: n=499.00–99.25 %: n=699.25–99.50 %: n=299.50–99.75 %: n=299.75–100.00 %: n=3median 98.61 Purity (% area) Reports
Figure 2. Purity distribution across all 36 LL-37 records. Dashed line is this compound's median (98.61 %); the solid vertical is the index acceptance specification for the tissue-repair and immunomodulatory peptides class (96.5 %). 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.

97.397.898.398.799.299.7100.1HomopeptideHomopeptide: Q1 99.05, median 99.30, Q3 99.58, n=12n=12SSASSA: Q1 97.97, median 98.31, Q3 98.66, n=12n=12TFCTFC: Q1 98.04, median 98.16, Q3 98.29, n=10outlier 97.51n=10FGPFGP: Q1 99.34, median 99.54, Q3 99.74, n=2n=2 Purity (% area)
Figure 3. LL-37 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
aggregated multimer+2.85mass-identical100%0.341.40
des-Leu1 (−113 Da)-0.38-113.08497%0.100.32
deamidated (+1 Da)-0.26+0.98492%0.131.05
trifluoroacetyl adduct (+96 Da)+0.84+95.98292%0.080.24
truncated (1-31)-1.68-709.40189%0.511.25

Degradation pathways

  • self-association into oligomers at physiological ionic strength
  • adsorptive loss on polypropylene — use glass

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

Section 7

Quarterly coverage

QuarterReportsMedian purityRange
2024-Q10n<3—
2024-Q21298.3197.68–99.01
2024-Q30n<3—
2024-Q40n<3—
2025-Q11098.1697.51–98.63
2025-Q20n<3—
2025-Q32n<399.15–99.93
2025-Q40n<3—
2026-Q10n<3—
2026-Q20n<3—
2026-Q31299.3098.84–99.93

Quarter-by-quarter detail →

Section 8

Most recent records

The 25 most recent LL-37 records of 36.
ReportSupplierLotLabQuarterPurity %Water %Recovery %ProvenanceFlagsResult
AX-2026-042216HomopeptideHOMO-2602-G1280Kestrel2026-Q398.975.3093.4Supplier-supplied1MARGINAL
AX-2026-042215HomopeptideHOMO-2602-G1280PeptideMeter2026-Q399.835.3689.9Supplier-supplied1MARGINAL
AX-2026-042217HomopeptideHOMO-2602-G1280Janoshik2026-Q399.435.69105.8Supplier-supplied1MARGINAL
AX-2026-042221HomopeptideHOMO-2602-G1280Janoshik2026-Q399.585.6296.7Supplier-supplied1MARGINAL
AX-2026-042210HomopeptideHOMO-2602-G1280PeptideMeter2026-Q399.365.23—Supplier-supplied1MARGINAL
AX-2026-042211HomopeptideHOMO-2602-G1280Medutest2026-Q399.235.76101.5Supplier-supplied1MARGINAL
AX-2026-042214HomopeptideHOMO-2602-G1280Kestrel2026-Q399.935.81—Supplier-supplied0PASS
AX-2026-042212HomopeptideHOMO-2602-G1280Janoshik2026-Q399.015.59105.5Supplier-supplied1MARGINAL
AX-2026-042220HomopeptideHOMO-2602-G1280Medutest2026-Q399.245.90106.1Supplier-supplied1MARGINAL
AX-2026-042219HomopeptideHOMO-2602-G1280Janoshik2026-Q398.845.5790.1Supplier-supplied1MARGINAL
AX-2026-042213HomopeptideHOMO-2602-G1280Janoshik2026-Q399.065.98100.5Supplier-supplied1MARGINAL
AX-2026-042218HomopeptideHOMO-2602-G1280Janoshik2026-Q399.585.94104.1Supplier-supplied0PASS
AX-2025-018996FGPFGP-2507-L2691Kestrel2025-Q399.934.94102.9Supplier-supplied0PASS
AX-2025-018995FGPFGP-2507-L2691Janoshik2025-Q399.154.60—Supplier-supplied1MARGINAL
AX-2025-019364TFCTFC-2410-N7616Janoshik2025-Q198.034.59104.4Buyer-sourced1MARGINAL
AX-2025-019359TFCTFC-2410-N7616Nordanalyt2025-Q198.253.67—Supplier-supplied2FAIL
AX-2025-019366TFCTFC-2410-N7616Nordanalyt2025-Q198.633.6298.1Supplier-supplied1MARGINAL
AX-2025-019362TFCTFC-2410-N7616PeptideMeter2025-Q197.514.3395.5Supplier-supplied2FAIL
AX-2025-019357TFCTFC-2410-N7616VendorInvestigate2025-Q198.064.09107.5Buyer-sourced1MARGINAL
AX-2025-019360TFCTFC-2410-N7616PeptideMeter2025-Q198.143.8696.6Supplier-supplied1MARGINAL
AX-2025-019365TFCTFC-2410-N7616Janoshik2025-Q197.994.0392.0Supplier-supplied0PASS
AX-2025-019363TFCTFC-2410-N7616Janoshik2025-Q198.334.18—Supplier-supplied1MARGINAL
AX-2025-019358TFCTFC-2410-N7616PeptideMeter2025-Q198.193.79—Supplier-supplied1MARGINAL
AX-2025-019361TFCTFC-2410-N7616Janoshik2025-Q198.303.9894.9Supplier-supplied1MARGINAL
AX-2024-005185SSASSA-2403-V6258Janoshik2024-Q298.282.11—Supplier-supplied1MARGINAL