Quick answer
Hexarelin contains two D-amino acids, so a buyer's guide has to go beyond "≥98% HPLC": ask for batch-specific HPLC with the trace, a mass-spec identity near 887 Da, and a supplier who can explain how stereochemistry is controlled.
- Sequence: His-D-2-methyl-Trp-Ala-Trp-D-Phe-Lys-NH2 (C47H58N12O6, about 887 g/mol)
- Gap in routine QC: standard HPLC and mass spectrometry generally cannot tell a D-residue from its L-isomer
- Documents to request: lot-matched CoA, chromatogram, mass-spec result, test date, testing lab
- Red flags: no mass data, no trace, reused CoAs, personal-use language, prices with no room for testing
- V8 listing: the hexarelin 5 mg research vial is listed at ≥98% HPLC with a batch-specific CoA; see the CoA page
- Research use: For laboratory research use only; not for human consumption.
What makes hexarelin different to source
For laboratory research use only; not for human consumption.
Hexarelin is a synthetic hexapeptide growth-hormone secretagogue studied for its interaction with the ghrelin receptor (GHS-R1a) and downstream effects on GH release pathways. Unlike simple linear peptides, hexarelin's sequence includes D-amino acid residues at specific positions that are critical to its receptor-binding geometry. The V8 listing gives the sequence as His-D-2-methyl-Trp-Ala-Trp-D-Phe-Lys-NH2: the second residue is a D-configured, 2-methylated tryptophan, the fifth is D-phenylalanine, and the C-terminus is an amide.
That raises the sourcing bar above what applies to a straightforward synthesis. A supplier that gets the stereochemistry wrong doesn't produce a slightly weaker version of hexarelin; it produces a different molecule that may show no relevant receptor activity at all.
| Position | Residue | Why it matters for quality control |
|---|---|---|
| 1 | His | Imidazole side chain; sensitive to trace metals and oxidation |
| 2 | D-2-methyl-Trp | Non-natural, D-configured; wrong building block gives the wrong mass or the wrong stereochemistry |
| 3 | Ala | Simple, but a coupling site for deletion products |
| 4 | Trp | Oxidation-prone indole; main source of +16 Da species |
| 5 | D-Phe | D-configured; racemization during synthesis can convert it toward L |
| 6 | Lys-NH2 | C-terminal amide; free-acid product is about 1 Da heavier |
Why stereochemistry-sensitive peptides need more scrutiny
Standard solid-phase peptide synthesis defaults to L-amino acids. Producing a peptide with D-amino acids at defined positions requires deliberate substitution during synthesis and tighter process control to avoid racemization elsewhere in the chain. For research purposes this means:
- A Certificate of Analysis showing only overall HPLC purity and total mass doesn't confirm correct stereochemistry — standard reverse-phase HPLC and standard mass spectrometry generally cannot distinguish D- from L-amino acid isomers at a given position.
- Suppliers working from a validated synthesis route with consistent process control are a materially different risk profile than suppliers assembling peptides ad hoc from generic building blocks.
- Unexpected or absent activity in a receptor-binding assay is sometimes a hexarelin stereochemistry problem before it's a biology problem — worth ruling out with a supplier who can speak to their synthesis process.
Diastereomers (same mass, different spatial arrangement at one center) are sometimes separable by a shallow HPLC gradient, appearing as a shoulder or a closely eluting second peak. That is one reason the chromatogram itself, not just the percentage, is worth requesting. Chiral amino acid analysis after hydrolysis can quantify D/L ratios directly, though it is not part of routine CoAs.
What a Certificate of Analysis should show
For any research peptide, a Certificate of Analysis is the primary quality document, and it should be tied to the specific batch shipped — not a generic reference document reused across production runs. See how to read a COA for a general walkthrough. For hexarelin specifically, look for:
- Mass spectrometry identity confirmation — confirms molecular weight matches the theoretical value for hexarelin (approximately 887 g/mol). This is the definitive identity check, and the gap HPLC alone leaves open. See HPLC vs. mass spectrometry.
- HPLC purity, with the chromatogram included — not just a stated percentage. A visible trace lets a researcher evaluate peak shape and assess what any minor impurities look like, rather than taking a number on faith. See understanding HPLC purity.
- Endotoxin testing (LAL assay or equivalent) — essential for any in vivo work. Endotoxin contamination from bacterial cell-wall components is a well-documented confounder that can independently produce inflammatory responses and complicate GH-axis readouts.
- Third-party verification — in-house-only testing has no independent check on it. See third-party testing explained.
- Storage and handling guidance — hexarelin should ship as a lyophilized powder with clear supplier-documented storage conditions. See the hexarelin research overview for handling background.
The identity check has a practical side. The mass window for the free hexapeptide amide is narrow, so any batch whose reported mass is off by more than instrument tolerance should be questioned. Common deviations are about +16 Da (oxidation at a tryptophan), about +1 Da (free-acid C-terminus rather than amide), and large negative shifts (deletion sequences). For a deeper treatment of verification, see hexarelin purity testing.
Red flags when evaluating a supplier
- No COA available, or a COA that lacks mass spectrometry data — identity is unconfirmed.
- Stated HPLC purity below 95% with no explanation, or no chromatogram provided alongside the number.
- No endotoxin testing data offered for material marketed as suitable for in vivo research.
- Product pages or marketing copy that reference usage instructions or personal-use guidance rather than staying within a research-use-only framing — a clear signal the supplier isn't operating within a compliant research-only model.
- Pricing dramatically below the market range for documented, batch-tested material, with no analytical paperwork to justify it. Proper synthesis (including D-amino acid incorporation), third-party testing, and legitimate cold-chain shipping all cost money; a price that leaves no room for any of that is a signal, not a bargain.
- A CoA with no test date, no lot number, or a lot number that does not match the vial.
The broader checklist is in red flags when buying research peptides.
Questions worth asking directly
A short, direct set of questions separates suppliers who can back up their documentation from ones who can't:
- Is the COA issued per batch, or reused across production runs?
- Was purity and identity testing performed by an independent third-party lab?
- Can the supplier speak specifically to how D-amino acid stereochemistry is controlled during synthesis?
- Does the labeled vial mass match what's described on both the product page and the COA?
- Is the result a typed number or an attached trace and spectrum?
Suppliers with nothing to hide answer these plainly. Vague answers or refusal to produce a batch-specific COA on request are reasons to look elsewhere.
Comparing specifications side by side
When two listings for the same compound look similar, compare them against the same checklist. The table below shows how to read the answers.
| Item | Strong answer | Weak answer |
|---|---|---|
| Purity claim | Percentage tied to HPLC, with trace and method | Bare number or "high purity" |
| Identity | Observed mass beside theoretical (about 887 Da) | No mass data |
| Stereochemistry | Supplier can describe the D-residue sourcing and controls | "Standard synthesis" |
| Batch link | Lot number on vial equals lot number on CoA | Same CoA for every purchase |
| Independent testing | Named outside laboratory | In-house only |
| Labeling | Research use only, no usage instructions | Personal-use language |
For hexarelin in particular, how it relates to other secretagogues affects what analytical context is useful; see hexarelin vs. ipamorelin.
Where to buy documented Hexarelin
V8 Peptides supplies Hexarelin as a lyophilized powder verified to ≥98% purity by HPLC, with mass-spectrometry-confirmed identity and a batch-specific Certificate of Analysis included with every order, shipped domestically via USPS. The research vial is available on the Hexarelin research vial product page, which lists a 5 mg size, the sequence above, a molecular formula of C47H58N12O6, and storage at 2–8 °C (−20 °C for long-term) away from heat, moisture and light. For background on the mechanism this sourcing bar exists to protect, see Hexarelin mechanism of action, and for sourcing criteria that apply across any research peptide purchase, see choosing a research peptide supplier. Once material arrives, the peptide calculator converts vial mass and diluent volume into a working concentration.
Frequently asked questions
Why is hexarelin harder to verify than a standard peptide?
It contains D-configured residues (D-2-methyl-Trp and D-Phe). Routine HPLC and mass spectrometry generally can't distinguish a D-residue from its L-isomer, so identity and stereochemistry need more than a purity percentage.
What mass should a hexarelin CoA report?
About 887 g/mol for the free hexapeptide amide (C47H58N12O6). The certificate should show observed and theoretical values together.
Is ≥98% HPLC purity enough?
It is a necessary figure but not sufficient. It says nothing about identity. Ask for the chromatogram and the mass-spec result, and check the lot number against your vial.
What does a +16 Da peak suggest?
Oxidation, most plausibly of a tryptophan indole, which can occur with poor storage or handling. A +1 Da offset may instead indicate a free-acid C-terminus.
Why ask about endotoxin testing?
Endotoxin from bacterial cell walls can independently trigger inflammatory responses and confound readouts. It is most relevant to in vivo work, so ask whether it has been tested.
Should every order come with its own CoA?
Yes. The CoA should be tied to the lot you received. Lot-level records can be checked on the CoA page.
Where can I read more on testing hexarelin lots?
See hexarelin purity testing for the analytical details behind these checks.
Research Use Only. For laboratory research use only; not for human consumption. Supplied strictly for laboratory research and development, not for human or veterinary use, and not for diagnostic purposes. This article is research education, not usage guidance.
References
- Hexarelin research overview (V8 Peptides)
- Hexarelin purity testing (V8 Peptides)
- How to read a CoA (V8 Peptides)
- Third-party testing explained (V8 Peptides)
- Hexarelin product specification (V8 Peptides)