IGF-1 LR3 lab tests

Seven checks before you trust a IGF-1 LR3 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 IGF-1 LR3 testing can and cannot rule out

IGF-1 LR3 is a recombinant fusion protein, not a synthetic peptide. Its parent, native human IGF-1, is a 70-residue single chain with three intramolecular disulfide bridges and a molecular weight of 7,649 Da — FDA's figure, from the approved mecasermin label (mature parent sequence: UniProt P05019). LR3 adds an N-terminal extension and a substitution at position 3, where native mature IGF-1 carries glutamate. The specification vendors quote for the finished analogue — 83 amino acids, an extension written as MFPAMPLSSLFVN, and a molecular weight of roughly 9,111 Da — has no source Peptigrity could find: a full-text Europe PMC search for that extension sequence returns zero hits across the indexed biomedical literature.

The founding paper (Francis, Ross, Ballard et al., Journal of Molecular Endocrinology, 1992, PMID 1378742) describes analogues comprising "an IGF-I sequence and the first 11 amino acids of methionyl porcine growth hormone" — eleven residues, not thirteen, which gives 81 residues rather than 83. The market figure is not shown to be wrong; it is unsourceable, and the primary paper appears to disagree with it. A wrong number can be corrected, while an unsourceable number cannot be checked at all: a certificate reporting a mass has nothing authoritative to be checked against, because the usual comparator is the same unsourced 9,111 Da circulating on the vendor pages being audited.

Mass spectrometry can still exclude the most plausible substitution. Native IGF-1 at 7,649 Da is far enough from any plausible LR3 mass to be unambiguous, so a batch-matched spectrum should at minimum exclude it — but a result reading "approximately 9,000 Da" is a measurement, not an identity confirmation. A second failure sits behind the first: the three disulfide bridges must pair correctly, incorrectly folded IGF-1 has exactly the same mass as correctly folded IGF-1 and is biologically inactive, and no routine certificate of analysis reports folding at all. HPLC cannot help, because a homogeneous sample of misfolded protein returns a clean chromatogram.

• Ask where the 9,111 Da figure comes from. A vendor who can produce a primary source has provided something new; a vendor who repeats the number without one has copied a specification rather than characterised a product. This check runs on the paperwork, not the vial.
• A batch-matched mass spectrum that at minimum excludes native IGF-1 at 7,649 Da, tied to the lot in hand rather than a specimen certificate from an earlier batch.
• Disulfide pairing: no routine certificate reports it, and mass spectrometry cannot see pairing at all. A vendor claiming MS proves correct folding is claiming something it cannot show.
• The word "recombinant" and a named expression system on the product page. Francis and colleagues expressed LR3 in E. coli in 1992, and a 2023 paper describes expression in Pichia pastoris. An 80-odd-residue disulfide-bonded protein sits at or beyond the edge of solid-phase peptide synthesis, so a page describing LR3 as a synthetic peptide made by SPPS is describing a route that does not produce this molecule.
• Fill quantity as its own line: quantity variance on this compound ran +1% to +72% (verified August 2026), and one June 2026 sample tested 72% over label — direct evidence that fill quantity is uncontrolled. It sits alongside the identity checks because hypoglycaemia is the signature adverse effect of the approved parent drug, at 42% incidence in a monitored paediatric population.
• Endotoxin (LAL) results are rarely reported on this compound.