Sermorelin lab tests

Seven checks before you trust a Sermorelin certificate

The same seven questions decide whether a certificate of analysis means anything, whichever compound it describes. Six are about the document; the seventh is about what no document can tell you.

1. An independent, batch-matched COA. The certificate must name the batch or lot in your hands, and must come from a laboratory the vendor neither owns nor pays. A specimen certificate from an earlier lot proves nothing about the vial you were sent.
2. HPLC purity, read against a known band. A purity figure is only informative against the distribution for that compound. "Above 98%" is not a claim — the useful question is whether the result sits inside the range the rest of the market reports. How to read HPLC and mass-spec results.
3. Mass-spectrometry identity. HPLC says how much of the sample is one thing; it does not say which thing. Only a mass-spec result establishes identity, and it is the only check that separates compounds a few daltons apart. Contamination is not hypothetical: research-grade custom peptides from two independent commercial suppliers were found to carry contaminating peptides at roughly 1% by weight, enough to produce false-positive results in immunology assays (Clinical and Vaccine Immunology, 2008 — a study of HIV vaccine peptide libraries rather than of any compound on this site).
4. Net content, measured rather than assumed. Purity and quantity are different questions: a vial can be 99.7% pure and still contain two thirds of the labelled mass. Why 10 mg isn't 10 mg.
5. Endotoxin (LAL) on the batch. An absent endotoxin line means the batch was not tested — not that it passed. Endotoxin testing and LAL interpretation.
6. Who ran the test, and what they left off. A laboratory with a record on this compound, named on the certificate, with a verification route back to it. Testing laboratories we track · Red flags in a certificate of analysis.
7. What no test on the vial can establish. A perfect certificate confirms that a vendor sold the correct molecule at the stated quantity. It says nothing about efficacy, dosing, or long-term safety.

Want a vial tested yourself? How to send a peptide for independent HPLC testing.

What sermorelin testing has to rule out: Mod GRF (1-29), 10 daltons away

Sermorelin is the unmodified first 29 amino acids of human growth hormone-releasing hormone, amidated: YADAIFTNSYRKVLGQLSARKLLQDIMSR-NH₂, CAS 86168-78-7 (PubChem CID 16132413), C₁₄₉H₂₄₆N₄₄O₄₂S, molecular weight 3,357.9 g/mol. Its nearest market rival, Mod GRF (1-29), sits just 10 Da away at 3,367.9 — a gap no HPLC purity figure addresses and a rounded nominal mass will not settle.

The Met27→Leu27 substitution that produces that gap also removes sermorelin's only sulfur atom, so the two differ in elemental composition as well as mass: C₁₄₉H₂₄₆N₄₄O₄₂S against C₁₅₂H₂₅₂N₄₄O₄₂. Sulfur present or sulfur absent is a binary a composition report can answer, and a composition matching the second formula is not sermorelin regardless of what the label says. CJC-1295 with DAC (C₁₆₅H₂₆₉N₄₇O₄₆, 3,647.2) is the easy case: it sits far enough clear of sermorelin that no instrument confuses the two.

• High-resolution mass spectrometry at 3,357.9 Da — not 3,367.9, which is Mod GRF (1-29), and not 3,647.2, which is CJC-1295 with DAC. A nominal mass reported without a decimal place is insufficient for a 10-dalton discrimination.
• Elemental composition showing sulfur present: the Met27 residue that Mod GRF (1-29) lacks.
• Database naming: querying "CJC-1295" in chemical databases returns the DAC form at 3,647.2, so a product sold as "CJC-1295" at 3,367.9 is Mod GRF (1-29) under a name that belongs to a different molecule — and it looks identical to sermorelin on every document except the identity result.
• Fill accuracy, in both directions: one vendor's sermorelin measured 12.88 mg against a 10 mg label, a 28.8% overage (recorded on the sermorelin compound page, verified August 2026). A fill line that runs 28.8% over is not being measured, the same absence of control produces shortfalls, and large overages belong in the red-flag column with shortfalls.
• Endotoxin (LAL) data is largely absent across sermorelin listings; most entries report nothing at all.