Effect of Pyruvate on the Redox Behavior of the Iron (III)-(II) Couple

Abstract

Evidence for the formation of Fe(III) and Fe(II) complexes with pyruvate ion is presented. Complexes with a 1:2 ratio of Fe(II) to pyruvate and 1:1 ratio of Fe(III) to pyruvate were identified by spectrophotometry. The complexation results in partial kinetic control of the electrochemical oxidation of Fe(II) in citrate buffer. In addition, Fe(III) was found to be chemically reduced by pyruvate. The apparent first order rate constant at 25[ddot]C is 7.12 × 10⁻² s ⁻¹in pH 4.0 pyruvate buffer and 1.24 × 10⁻¹ s ⁻¹ in pH 3.2 pyruvate buffer. In pH 4.0 citrate buffer the reaction is not first order and is significantly slower.

Key Words:

• iron
• pyruvate
• complexation
• chemical reduction
• voltammetry