Duloxetine EP Impurity A, chemically defined as (R)-N-Methyl-3-(naphthalen-1-yloxy)-3-(thiophen-2-yl)propan-1-amine hydrochloride and also designated Duloxetine USP Related Compound A, is the (R)-enantiomer (distomer) of Duloxetine, with molecular formula C₁₈H₁₉NOS·HCl and molecular weight 333.87 g/mol (free base 297.42 g/mol). As the mirror-image stereoisomer of the therapeutically used (S)-configured API, this impurity arises from incomplete stereochemical control, either during enantioselective reduction or during classical resolution of the racemic amino-alcohol or final amine intermediates, and it must be controlled because the (R)-enantiomer is considerably less potent. This makes it a critical enantiomeric purity marker for chiral method development. Manufactured at Chemicea under tightly controlled synthesis and purification protocols, this reference standard supports chiral HPLC method validation, enantiomeric purity (ee) determination, and quality-control testing throughout Duloxetine Hydrochloride API and delayed-release formulation development, in accordance with EP and USP monograph requirements. Each batch is supplied with a comprehensive Certificate of Analysis supported by chiral HPLC, ¹H-NMR, and Mass Spectrometry data, ensuring reliable analytical traceability for regulatory submissions. CAS No. 910138-96-4 (hydrochloride; free base CAS No. 116539-60-7) | Explore complete technical documentation, Safety Data Sheet (SDS), and pricing.