ELECTROCHEMISTRY OF BRUCINE .2. THE BRUCINE BASED DETERMINATION OF NITRATE

The electrochemical and chemical reactions of brucine following an oxi dation step were investigated by cyclic voltammetry, chronocoulometry, bulk electrolysis, visible spectrophotometry, and electrospray mass s pectrometry with the goal of better understanding the brucine-based de termination of nitrate, The experiments were performed in acidic solut ion (0.010-7.0 M sulfuric acid) using carbon paste, glassy carbon, and platinum electrodes, Following a two-electron oxidation (E(p) = 0.90- 1.15 V vs Ag/AgCl), brucine(2+) reacts with water to form an aminochro me (brucichrome) plus methanol, Brucichrome undergoes a reversible two -electron reduction (E degrees' = 0.54 V, 0.01-7.0 M sulfuric acid) to form a hydroquinone and also slowly dimerizes, The dimer is also an a minochrome, and it, too, undergoes a reversible two-electron reduction (E degrees' = 0.39 V), The primary evidence for a dimeric final produ ct comes from electrospray mass spectrometry during electrolysis, elem ental analysis, and H-NMR on a product isolated from bulk electrolysis in HCl.