HPLC-fluorescence determination of chlorocresol and chloroxylenol in pharmaceuticals

The use of 2-chloro-6,7-dimethoxy-3-quinolinecarboxaldehyde as a fluorogenic labelling reagent in pre-column derivatization for the HPLC separation of chlorophenols has been investigated. The compound reacts (50 min at 110 degrees C) with 2- and 4-chlorophenols to give fluorescent ethers that can be separated by reversed-phase HPLC and detected at lambda exc = 360 nm, lambda em = 500 nm. The experimental conditions for derivatization and chromatographic separation are discussed. Applications for the determination of chlorocresol (4-chloro-3-cresol) and chloroxylenol (4-chloro-3,5-xylenol) in pharmaceutical formulations (creams, ointments) are described.