| CAS No. | 4999-78-4 |
| Molecular Formula | C18H23O5S |
| Molecular Weight | N/A |
| Category | Pharmacopoeial Impurity Standards / EP Impurities |
| Availability | In Stock |
CATO supplies Estradiol Impurity 41 (CAS 4999-78-4), a pharmacopoeial impurity reference standard (molecular formula C18H23O5SNa, MW 374.43 g/mol) used for the identification and quantification of trace impurities in APIs.
Structurally, Estradiol Impurity 41 (C18H23O5SNa) contains a flavonoid core, a sulfone group, a hydroxyl group, an ether linkage. The molecule exhibits a degree of unsaturation (DBE) of 7.5, corresponding to approximately 7 ring(s) or double-bond equivalent(s). With a molecular weight of 374.43 g/mol, it falls into the moderately-high-molecular-weight range. The aromatic system may exhibit native fluorescence, enabling detection with a fluorescence detector (FLD).
This reference standard supports related-substances testing and method development in line with ICH Q3A/Q3B guidance on impurity control, and is suitable for system suitability testing and forced-degradation studies.
The assigned purity is verified by mass-balance and quantitative NMR (qNMR) approaches, with the expanded uncertainty reported at a 95% confidence level (k=2). Batch homogeneity and stability are independently assessed for every lot.
| Molecular Formula | C18H23O5S Na |
| Molecular Weight | 374.43 g/mol |
| Purity | 97%+ |
| Storage | Store at 2-8°C, protect from light, keep sealed and dry |
| Solubility (reference) | Soluble in methanol, acetonitrile, DMSO, water (slightly soluble) |
| Stability | May oxidize slowly on prolonged air exposure; Light-sensitive; avoid direct strong light |
| Degree of Unsaturation (DBE) | 7.5 |
| UV Absorption | UV-absorbing |
| Structural Features | Aromatic ring present |
| CAS Registry Year (est.) | 1958 |
| Sulfur Atoms | 1 |