Post-column oxidative derivatization for the liquid chromatographic determination of phenothiazines

A first post-column chemical derivatization method for the liquid chromatog raphic determination of phenothiazines is presented. Peroxyacetic acid is i ntroduced as a derivatizing agent for phenothiazines, yielding the colored radical cations or fluorescent sulfoxides, depending on reaction conditions . Both reaction products were successfully employed for the detection of th e phenothiazines after their liquid chromatographic separation. The fluores cence spectroscopic detection of the sulfoxides proved to be the more robus t and sensitive method. Limits of detection ranged from 4 nM for trifluprom azine and trimeprazine to 300 nM for phenothiazine for the fluorescence spe ctroscopic detection of the sulfoxide and from 0.3 mu M for phenothiazine a nd triflupromazine to 2 mu M for trifluperazine for the UV-Vis spectroscopi c detection of the radical cation. The calibration functions for the fluori metric sulfoxide determination ranged from two to more than three decades, starting at the limit of quantification. (C) 2000 Elsevier Science B.V. All rights reserved.