Determination of dihydrozeatin and dihydrozeatin riboside in apples by anodic stripping voltammetry with a carbon fiber microelectrode

Analytical methods for determining both dihydrozeatin (DHZ) and dihydrozeatin riboside (DHZR) are optimized via voltammetric anodic stripping using a carbon fiber microelectrode, working in 0.05 M AcH/Ac^– buffer pH 4.0, previously accumulated at 0.00 V (vs. Ag/AgCl/ KCl 3 M) for 400 s, at a scan rate of 800 mV · s^–1. A detection limit of 40.0 ng · mL^–1 and a determination limit of 46.0 ng · mL^–1 for the DHZ are obtained. Using the same supporting electrolyte and accumulation potential conditions, but for periods of 70 s and carrying out a stripping scan rate of 900 mV s^–1, the detection limit calculated for the DHZR was 14.0 ng · mL^–1 and the determination limit obtained was 153 ng · mL^–1. The proposed methods were successfully applied to determine minute amounts of cytokinins in apples during their growth period. Received: 22 July 1998 / Revised: 9 December 1998 / Accepted: 14 December 1998