Determination of 2-chloro-4,5-difluorobenzoic acid and related impurities by liquid chromatography

✍ Scribed by Lee Elrod Jr.; Stephen G. Spanton; Moike Cirovic; Dean I. Shaffer; Timothy G. Golich; Cathie L. Linton; Douglas R. Vievia; Pano Kalaritis; Horst Schmand

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 591 KB
• Volume: 280
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(93)80245-g

✦ Synopsis

2-Chloro-4,5-difluorobenxoic acid (CDFBA) and related impurities are determined using liquid chromatography (LC). Separations are achieved using a reversed-phase isocratic system with an ion-pair reagent (tetrabutylammonium hydroxide). Unique isomeric impurities observed in commercially produced CDPBA were isolated and identified by NMR and single crystal x-ray diffraction. The method has relative standard deviations of f 0.55% to f 1.26% for the CDPBA determination and from *4.3% to f 12% for impurities below 0.3% in CDPBA. Impurities are determinable to at least 0.03% by weight.