FLOW-INJECTION BIAMPEROMETRIC DIRECT DETERMINATION OF HYDRAZINE AT TWO OXIDE-MODIFIED PLATINUM ELECTRODES

A new electrochemical method for the direct determination of hydrazine has been designed for flow injection analysis. The method is based on coupling two independent and irreversible electrode processes, the electrocatalytic oxidization of hydrazine and the reduction of platinum oxide, to form a biamperometric detection system. The measuring conditions are optimized. In operation, a potential difference of 0.00 V is imposed between two identical platinum wire electrodes pretreated by an anodization step, and the resulting current is measured. The linear relationship between the current and the concentration of hydrazine is obtained in the range of 1 × 10-7 to 1 × 10-5 mol l-1 with a detection limit of 8 × 10-8 mol l-1. Most cations, anions and organic compounds tested are found not to cause significant interference in the determination of hydrazine. The stability of the method is shown by relative standard deviation (1.7%) for 24 replicate determinations of 2 × 10-6 mol l-1 hydrazine. The method has been validated by the determination of hydrazine in water samples.