Mass spectrometric analysis of cytokinins in plant tissue VII. Quantification of cytokinin bases by negative ion mass spectrometry

A study of derivatives of N⁶-(isopent-2-enyl)adenine formed by substitution at N-9 indicated that sensitivity of detection by chemical ionization mass spectrometry was maximized by a pentafluorobenzyl substituent and negative ion monitoring. O-t-Butyldimethylsilyl-9-pentafluorobenzyl derivatives of zeatin (Z),cis-zeatin (cis-Z), and dihydrozeatin (DZ) were characterized by mass spectrometry. A procedure was based on these stable derivatives and negative ion chemical ionization mass spectrometry for quantification of zeatin and dihydrozeatin in plant tissue.For part VI, see Letham and Singh (1989).