Development of a Method for Regioisomer Impurity Detection and Quantitation within the Raw Material 3-Chloro-5-Fluorophenol by Gas Chromatography

Control of regioisomer impurities within pharmaceutical raw materials, intermediates, and active pharmaceutical ingredients are of major concern for the pharmaceutical industry. If regioisomer impurities are possible, their detection and quantitation should be established as early as possible within the process. This work describes a gas chromatography area% method for the detection and quantitation of all regioisomer impurities associated with 3-chloro-5-fluorophenol, a raw material used within the pharmaceutical industry along with other related impurities found within 3-chloro-5-fluorophenol. Several method development aspects, as well as a general regioisomer impurity control strategy related to 3-chloro-5-fluorophenol are discussed.