LIQUID SECONDARY IONIZATION MASS-SPECTROMETRY AND COLLISION-INDUCED DISSOCIATION STUDY OF 2-CHLORO-N-10-SUBSTITUTED PHENOXAZINES

Positive-ion liquid secondary ionization mass spectrometry in combinat ion with 3-nitrobenzyl alcohol as the liquid matrix was used to invest igate the mass spectral features of a set of 21 N-10-substituted deriv atives of 2-chlorophenoxaine. The N-10 substitution included propyl, b utyl and acetyl groups containing various secondary amines (N,N-diethy lamine, N,N-diethanolamine, morpholine, piperidine, pyrrolidone or bet a-hydroxyethylpiperazine) or a chloro group, These compounds are poten t multi-drug resistance modulators, The molecular ions are observed as M+. and [M + H](+) ions, In general, the fragmentation pathways of th ese molecules are similar and very straightforward. The phenoxazine ri ng system remains stable under the Cs+ ion beam bombardment conditions , while fragmentations are observed along the length of the alkyl and acetyl side-chains, The fragmentation reactions were corroborated by a cquiring product ion and constant neutral loss tandem mass spectrometr ic scans of the pertinent ions. (C) 1997 John Wiley & Sons, Ltd.