Voltammetric behavior of indole-3-acetic acid and kinetin at pencil-lead graphite electrode and their simultaneous determination in the presence of anionic surfactant

A method was developed for the simultaneous determination of indole-3-acetic acid (IAA) and kinetin, based on the oxidation of both phytohormones at a pencil-lead graphite electrode. The electrochemical behaviors were examined by cyclic, linear sweep, and square-wave voltammetry in the pH range of 2-12. In Britton-Robinson buffer solution (pH 6), the oxidation peaks of IAA and kinetin are well separated by square-wave voltammetry. By adding an anionic surfactant (sodium dodecylsulfate) in a concentration of 50 mu M, the sensitivity of kinetin was increased significantly without reducing the resolution. The detection limits were 0.14 and 0.11 mu M (24.53 and 23.67 ng mL(-1)) for IAA and kinetin, respectively. Applicability to assays of maize plant extracts was illustrated.