FERROCENEBORONIC ACID AS A DERIVATIZATION REAGENT FOR THE DETERMINATION OF BRASSINOSTEROIDS BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH ELECTROCHEMICAL DETECTION

A micro-scale method for the determination of brassinosteroids as ferroceneboronates by high-performance liquid chromatography with electrochemical detection has been developed. Ferroceneboronic acid (FBA) proved to be satisfactory for use in the derivatization of brassinosteroids with respect to reactivity and sensitivity. The steroids were readily condensed with FBA under mild conditions to provide the corresponding boronates, exhibiting maximum sensitivity at + 0.6 V vs. a silver-silver chloride reference electrode with a detection limit of 25 pg for brassinolide. The method was successfully applied to the determination of natural brassinosteroids in a plant. Brassinolide, dolichosterone, norcastasterone and castasterone were identified in the pollen of sunflower (Helianthus annuus L.). © 1990.