AOD-9604 Research Guide 2026: hGH Fragment 176-191 Background, Handling & Purity

RESEARCH

Published September 1, 2026

AOD-9604 Research Guide 2026: hGH Fragment 176-191 Background, Handling & Purity

Compliance notice: This article is for laboratory research use only. It is not medical advice, not for human consumption, and not intended to diagnose, treat, cure, or prevent any disease.

AOD-9604 shows up in procurement lists more often than it shows up in careful documentation, and that gap is worth closing. It is a short synthetic peptide derived from the tail end of the human growth hormone molecule, and almost everything that makes it interesting to investigators comes from what it leaves out rather than what it adds. This guide covers what AOD-9604 actually is, where the research literature on it came from, how it is handled in a lab setting, and what to verify on a certificate of analysis before a vial ever enters a study.

What AOD-9604 Is: Structure and Identity

AOD-9604 is a modified fragment corresponding to the C-terminal region of human growth hormone, residues 176-191, with an additional tyrosine at the N-terminus. That tyrosine is not decoration; it is a synthesis and stability modification that distinguishes the compound from the raw native fragment. The molecule carries an intramolecular disulfide bridge, which is why its handling profile is closer to a structured peptide than to a simple linear chain.

The identifiers most commonly listed in supplier documentation are CAS 221231-10-3 and a molecular weight in the region of 1815 daltons for the free base. Treat those as a cross-check, not as gospel. The number that governs your work is the one printed on the mass spectrometry trace for the specific lot in your freezer. If a supplier's product page and its COA disagree on molecular weight, that discrepancy is the finding, and it should be resolved before anything is reconstituted.

Where the AOD-9604 Research Literature Came From

Interest in this fragment traces back to work in Australia in the 1990s and 2000s investigating whether the lipolytic region of growth hormone could be separated from the rest of the molecule's activity. The premise was structural: if the metabolic behavior investigators wanted to study lived in the C-terminal domain, then a fragment might reproduce that behavior in preclinical models without carrying along the receptor interactions attributed to the full-length hormone.

That framing is the entire reason AOD-9604 remains a reference compound in comparative studies today. It is used as a structural control against full-length growth hormone and against secretagogue peptides that act further upstream. Precision Labs stocks related reference material for exactly this kind of comparison, including hGH 6 mg, Sermorelin 5 mg, and Ipamorelin 5 mg. No claim is made here about outcomes in humans; the relevance is methodological.

Reconstitution, Storage, and Handling

AOD-9604 arrives lyophilized, and lyophilized is its stable state. Vials should sit refrigerated and shielded from light on arrival, and long-term holding is conventionally done frozen. The important discipline is temperature consistency rather than temperature extremes. Repeated freeze-thaw cycling is a far more common cause of degraded reconstituted peptide than any single storage decision.

When reconstituting, direct the diluent stream down the vial wall rather than onto the cake, and let the powder dissolve on its own instead of shaking it into solution. Peptides with disulfide structure are exactly the ones that punish vigorous agitation. Bacteriostatic water is the usual diluent when the stock will be sampled more than once, since a preservative-free vial is treated as single-entry after the closure is breached. If the distinction is unfamiliar, our bacteriostatic water vs sterile water guide covers it in full, and diluent is stocked in 3 mL and 10 mL presentations.

Once in solution, label the vial with the date of first puncture, keep it cold, and protect it from light. For the broader workflow, see the peptide storage and handling guide and the step-by-step reconstitution guide.

Purity: What to Actually Read on the COA

A stated purity percentage on its own is close to meaningless without the document behind it. For a fragment like AOD-9604, four things carry the weight:

Lot matching. The lot number on the COA must match the lot number on the vial label. A generic catalog COA describes a batch you did not receive.

HPLC purity with a visible chromatogram. The trace shows impurity peaks and where they sit. A bare percentage hides them.

Mass spectrometry confirming identity. Purity says how much of one thing is present. Mass spec says whether that thing is the compound you ordered.

Test date and testing party. An undated COA, or one with no identifiable lab, is a marketing document.

Our guide to reading a peptide COA walks through each of these with what a clean document looks like, and the lab testing page sets out the verification standard applied across the catalog.

Research FAQ

What is AOD-9604? It is a synthetic peptide corresponding to the C-terminal 176-191 region of human growth hormone with an added N-terminal tyrosine, supplied as a lyophilized powder for laboratory research use only.

How does AOD-9604 differ from full-length hGH? Structurally, it is a short fragment rather than the complete 191-amino-acid hormone. That structural difference is the reason it appears in comparative preclinical work; it is not a statement about equivalence or effect.

What diluent is used to reconstitute AOD-9604? Bacteriostatic water is the conventional choice when the reconstituted stock will be sampled more than once. Preservative-free sterile water is treated as single-entry once opened.

How should AOD-9604 be stored? Lyophilized vials are held refrigerated on arrival and frozen for long-term storage, protected from light. Reconstituted material is kept cold and dated at first puncture, and freeze-thaw cycling should be minimized.

What should a COA for AOD-9604 include? A matching lot number, HPLC purity with the chromatogram shown, mass spectrometry confirming identity and molecular weight, plus the test date and the identity of the testing party.

Sourcing AOD-9604 for Research

Precision Labs supplies AOD-9604 10 mg with lot-specific documentation available on request. If you need the COA for a particular lot before placing a research order, or you need a comparison lot held for a study, contact Precision Labs and we will pull it. Research use only; not for human consumption.