Ingredient identity and composition
S-equol is a specific stereoisomer of equol, a compound associated with daidzein metabolism. It is distinct from soy isoflavones; its identity, specification and evidence should be assessed separately.
| Ingredient | (S)-Equol |
|---|---|
| CAS number | 531-95-3 |
| Molecular formula | C₁₅H₁₄O₃ |
| Molecular weight | 242.27 g/mol |
| Appearance | White powder |
| Purity | ≥99% (HPLC) |
Analytical documentation
The reference TDS specifies ≥99% purity by HPLC. For purchasing decisions, request the current controlled TDS, analytical methods and a batch-specific certificate of analysis.
Additional analytical parameters in the reference TDS
The TDS dated 22 July 2026 separately lists an HPLC assay range of 98.0–102.0% and specific rotation of [α]D < −21° at c = 5.0 g/L in ethanol.
These are reported specification parameters, not individual batch results. Confirm their methods and acceptance criteria in the current technical documentation.
Physical and quality parameters
| Particle size | 95% passes 60 mesh |
|---|---|
| Melting point | 189–190°C |
| Loss on drying | ≤1% |
| Residual ethanol | <200 ppm |
| Pb / As / Cd / Hg | Each ≤1.0 ppm |
| Total heavy metals | ≤10 ppm |
| Total aerobic count | ≤1,000 CFU/g |
| Yeast & mold | ≤100 CFU/g |
| Specified pathogens | E. coli, Salmonella and S. aureus: absent* |
*Confirm the test method and sample quantity in the current master specification and laboratory report. Specification limits are not individual batch results.
Solubility, storage and shelf life
The TDS describes S-equol as insoluble in water. Keep the ingredient sealed in a cool, dry place, protected from light and moisture.
These periods describe different information. Confirm the approved shelf-life claim, storage conditions and supporting stability package with the current master specification before purchase. Ingredient data do not establish finished-product stability.
Explore S-equol formulation considerations →