Doxycycline Impurity 21 CAS CATO-C4X-193121
| CAS No. | CATO-C4X-193121 |
| Molecular Formula | C23H25NO8 |
| Molecular Weight | 443.45 g/mol |
| Category | Pharmacopoeial Impurity Standards / EP Impurities |
| Availability | In Stock |
Chemical Structure
Description
Recommended for quantitative analysis by HPLC, GC, LC-MS/MS, or GC-MS as an external calibration standard; it can also be used for spiked-recovery experiments, LOD/LOQ determination, and LC-MS/MS multiple-reaction-monitoring (MRM) calibration.
Doxycycline Impurity 21 (CAS CATO-C4X-193121) is a certified pharmaceutical impurity reference standard with the molecular formula C23H25NO8 and a molecular weight of 443.45 g/mol.
Doxycycline Impurity 21 (C23H25NO8) contains a flavonoid core, an amide group, a hydroxyl group, an ether linkage. The carboxyl group imparts weak acidity; these physicochemical properties determine the optimal preparation and storage of its standard solutions. The presence of an aromatic ring or conjugated system gives the compound characteristic absorption bands in the UV-Vis region, making it well suited to UV or diode-array detection (DAD).
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.
Physical & Chemical Properties
| Molecular Formula | C23H25NO8 |
| Molecular Weight | 443.45 g/mol |
| Appearance | Pale yellow to yellow crystalline powder |
| Purity | 97%+ |
| Storage | Store at room temperature, 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) | 12.0 |
| UV Absorption | UV-absorbing |
| Structural Features | Aromatic ring present |
| Nitrogen Atoms | 1 |
Related Doxycycline Standards
- Doxycycline EP Impurity F (CAS 122861-53-4)
- Doxycycline EP Impurity A (CAS 3219-99-6)
- Doxycycline EP Impurity C (CAS 6543-77-7)
- Doxycycline EP Impurity D (CAS 97583-08-9)
- Doxycycline Impurity 8 (CAS CATO-C4X-19318)
- Doxycycline (CAS 564-25-0)
- Doxycycline EP Impurity B (CAS CATO-C4X-19312)
- Doxycycline-d3 (CAS 2747918-45-0)
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