BRUCINE .1. ELECTROCHEMISTRY OF BRUCINE

Cyclic voltammetry and chronocoulometry were used to study the electrochemistry of brucine. The oxidation of brucine 0.9 V versus a saturated calomel electrode at a carbon paste electrode produces a compound that undergoes reversible electrochemical behavior at Eo′ = 0.47 V. The product formed on the oxidation of brucine undergoes a slow chemical reaction to produce a compound that shows reversible behavior at Eo′ = 0.27 V. The hexadecane content of the carbon paste plays an important role in the observed behavior. Electrodes with low hexadecane did show oxidation of brucine, but irreversible waves occurred at Eo′ = 0.47 and 0.27 V. These features were also displayed by a platinum electrode. Calcium oxalate incorporated into the carbon paste catalyzes the oxidation of brucine. Chronocoulometry was used to estimate the heterogenous rate constant for the oxidation of brucine at calcium oxalate‐modified and unmodified electrodes. The values found were 21.4 × 10−3 cm/s for the modified electrode and 6.1 × 10−3 cm/s for the unmodified electrode. Preliminary results on the use of brucine as a reagent for the determination of nitrate are given. Copyright © 1990 VCH Publishers, Inc.