Semax
Met-Glu-His-Phe-Pro-Gly-Pro · ACTH (4-7) PGP · C37H51N9O10S · monoisotopic 813.3541 Da. The index holds 216 assay reports on this compound across 31 batches from 17 suppliers.
Analytical fingerprint
Hand-authored chemistry. These properties describe the substance and do not change when a record is added.
Semax carries a free N-terminal methionine, which is about the most oxidation-prone arrangement available, and the index's semax records show sulfoxide levels averaging 1.1 % area — the highest mean oxidation level of any compound tracked. That is mostly a storage artefact rather than a synthesis one: dry, cold, dark lots come in at 0.2–0.4 %. Semax is the index's standard example when explaining why an old COA does not describe the vial in your hand.
- Compound class
- Neuroactive and cognitive peptides
- Molecular formula
- C37H51N9O10S
- Monoisotopic mass
- 813.3541Da
- Average mass
- 813.93Da
- Residues
- 7
- Nominal retention (RG-2, 30 min)
- 7.06min
- Retention window
- 0.25min
- Counter-ion as usually shipped
- acetate
- Typical label claims
- 5 mg · 10 mg · 20 mg
- Analytical difficulty (index scale)
- 0.85 — straightforward
- Purity is a defined quantity
- YES
Representative chromatogram
Drawn from this page's own medians. Not a scan, not an illustration, and not any single report.
What the index has observed
Arithmetic over the 216 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.
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.
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 species | ΔRT (min, RG-2) | Δ mass (Da) | Seen in | Median % area | Max % area |
|---|---|---|---|---|---|
| Met1 sulfoxide (+16 Da) | -0.36 | +15.995 | 95% | 0.16 | 1.04 |
| des-Met (−131 Da) | +0.20 | -131.040 | 92% | 0.08 | 0.87 |
| diketopiperazine (−18 Da) | +0.16 | -18.011 | 88% | 0.12 | 1.35 |
| N-acetyl semax (+42 Da) | +0.42 | +42.011 | 87% | 0.11 | 0.91 |
Degradation pathways
- Met1 oxidation — an N-terminal methionine on a hygroscopic cake is a bad combination
- diketopiperazine formation
Full impurity profile, with what each named species implies about the synthesis →