AssayIndex
Neuroactive and cognitive peptides

Dihexa

N-hexanoic-Tyr-Ile-(6) aminohexanoic amide · PNB-0408 · C27H44N4O5 · monoisotopic 504.3312 Da. The index holds 35 assay reports on this compound across 7 batches from 6 suppliers.

35 reports7 batchesmedian 99.84 %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.

Dihexa is a lipidated tripeptide amide and is far more hydrophobic than its size suggests — it elutes at 12.2 min, later than several 30-mers. It also has no ionisable counter-ion in the usual sense, so counter-ion determination is reported as not applicable and the gravimetric mass balance closes on water plus residual solvent alone. It is the index's cleanest illustration of why lipophilicity and molecular weight are independent axes on a C18 column.

Molecular formula
C27H44N4O5
Monoisotopic mass
504.3312Da
Average mass
504.67Da
Residues
3
Nominal retention (RG-2, 30 min)
12.24min
Retention window
0.30min
Counter-ion as usually shipped
none expected
Typical label claims
5 mg · 10 mg · 20 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.

02203440566088811 Dihexa12.24 min · 99.84 % 9.8212.50 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 Dihexa trace on the index reference method RG-2, constructed from this page's own numbers: the main peak carries the index median purity of 99.84 % area at the nominal retention time of 12.24 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 35 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 99.84% n=35
Interquartile range 0.50pp n=35
Minimum 98.92% n=35
Maximum 99.93% n=35
Pass rate vs spec 100.0% n=35
Median recovery vs claim 102.9% n=15
Median water 7.09% n=35
Median |mass error| 3.0ppm n=28
06121892.093.094.095.096.097.098.099.0100.092.00–92.25 %: 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=097.75–98.00 %: n=098.00–98.25 %: n=098.25–98.50 %: n=098.50–98.75 %: n=098.75–99.00 %: n=299.00–99.25 %: n=199.25–99.50 %: n=999.50–99.75 %: n=599.75–100.00 %: n=18median 99.84 Purity (% area) Reports
Figure 2. Purity distribution across all 35 Dihexa records. Dashed line is this compound's median (99.84 %); the solid vertical is the index acceptance specification for the neuroactive and cognitive 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.

98.899.099.299.499.699.8100.0QYBQYB: Q1 99.92, median 99.93, Q3 99.93, n=12outlier 99.67outlier 99.88outlier 99.90n=12TFCTFC: Q1 99.29, median 99.51, Q3 99.75, n=12n=12QSCQSC: Q1 99.27, median 99.31, Q3 99.78, n=6n=6WWBWWB: Q1 99.71, median 99.93, Q3 99.93, n=3n=3 Purity (% area)
Figure 3. Dihexa 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
des-hexanoyl (−98 Da)-2.42-98.07497%0.060.45
free acid (+1 Da)+0.26+0.98477%0.060.47
[D-Ile]-epimer-0.14mass-identical77%0.040.18
hexanoyl bis-adduct (+98 Da)+2.30+98.07454%0.060.52

Degradation pathways

  • hexanoyl amide hydrolysis
  • C-terminal amide hydrolysis

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

Section 7

Quarterly coverage

QuarterReportsMedian purityRange
2024-Q10n<3—
2024-Q20n<3—
2024-Q30n<3—
2024-Q40n<3—
2025-Q11399.4998.92–99.93
2025-Q20n<3—
2025-Q31499.9399.67–99.93
2025-Q40n<3—
2026-Q11n<3—
2026-Q2799.3598.98–99.93
2026-Q30n<3—

Quarter-by-quarter detail →

Section 8

Most recent records

The 25 most recent Dihexa records of 35.
ReportSupplierLotLabQuarterPurity %Water %Recovery %ProvenanceFlagsResult
AX-2026-041598QSCQSC-2512-D7108VendorInvestigate2026-Q298.986.8599.4Laboratory-retained1MARGINAL
AX-2026-041597QSCQSC-2512-D7108PeptideMeter2026-Q299.356.42106.3Supplier-supplied1MARGINAL
AX-2026-041370WWBWWB-2601-C4091Kestrel2026-Q299.4910.92—Supplier-supplied1MARGINAL
AX-2026-041602QSCQSC-2512-D7108Nordanalyt2026-Q299.935.89—Supplier-supplied0PASS
AX-2026-041599QSCQSC-2512-D7108Nordanalyt2026-Q299.936.0395.9Supplier-supplied0PASS
AX-2026-041600QSCQSC-2512-D7108Nordanalyt2026-Q299.276.20—Supplier-supplied1MARGINAL
AX-2026-041601QSCQSC-2512-D7108Janoshik2026-Q299.286.50—Supplier-supplied2MARGINAL
AX-2026-042263HomopeptideHOMO-2509-M1537Medutest2026-Q199.586.75—Supplier-supplied2MARGINAL
AX-2025-018683QYBQYB-2503-Y6694Medutest2025-Q399.937.57—Supplier-supplied1MARGINAL
AX-2025-018680QYBQYB-2503-Y6694Nordanalyt2025-Q399.907.77—Supplier-supplied1MARGINAL
AX-2025-018686QYBQYB-2503-Y6694Janoshik2025-Q399.937.89105.8Supplier-supplied0PASS
AX-2025-018687QYBQYB-2503-Y6694Medutest2025-Q399.937.58—Supplier-supplied1MARGINAL
AX-2025-018681QYBQYB-2503-Y6694Medutest2025-Q399.887.09100.0Supplier-supplied1MARGINAL
AX-2025-018677QYBQYB-2503-Y6694Kestrel2025-Q399.938.20—Supplier-supplied1MARGINAL
AX-2025-018678QYBQYB-2503-Y6694Janoshik2025-Q399.677.09—Supplier-supplied1MARGINAL
AX-2025-018407WWBWWB-2507-N1598Janoshik2025-Q399.938.7497.3Supplier-supplied1MARGINAL
AX-2025-018676QYBQYB-2503-Y6694Medutest2025-Q399.937.81107.2Supplier-supplied1MARGINAL
AX-2025-018685QYBQYB-2503-Y6694Janoshik2025-Q399.937.03—Supplier-supplied1MARGINAL
AX-2025-018679QYBQYB-2503-Y6694Janoshik2025-Q399.938.19107.5Supplier-supplied1MARGINAL
AX-2025-018408WWBWWB-2507-N1598Janoshik2025-Q399.939.02—Supplier-supplied2FAIL
AX-2025-018684QYBQYB-2503-Y6694Janoshik2025-Q399.937.9391.4Supplier-supplied0PASS
AX-2025-018682QYBQYB-2503-Y6694Kestrel2025-Q399.937.88—Supplier-supplied0PASS
AX-2025-019291TFCTFC-2409-U6527Medutest2025-Q199.936.68—Supplier-supplied1MARGINAL
AX-2025-019290TFCTFC-2409-U6527VendorInvestigate2025-Q199.497.39—Buyer-sourced1MARGINAL
AX-2025-019289TFCTFC-2409-U6527Janoshik2025-Q199.277.1294.7Supplier-supplied1MARGINAL