In this paper, voltammetric determination of hydrazine was investigated by 1-amino-2-naphtol-4-sulfonic acid (ANSA) at the surface of carbon paste electrode (CPE) using cyclic voltammetry (CV) and double potential step chronoamperometry. Results showed that in pH 7.00, hydrazine participates in Michael addition reaction with ANSAand the anodic peak potential of hydrazine shifted to 726 mV less positive than CPE in absence of ANSA, this value is unique compared with other research works. Also, the value of rate constant for the oxidation of hydrazine was calculated 8.3 × 104 cm3 mol-1 s-1 and the diffusion coefficient of ANSA at the surface of CPE was determined 7.3 × 10-7 cm2 s-1. A linear correlation between Ip and hydrazine concentration in the ranges, from 5 × 10-5 mol/L to 2.5 × 10-2 mol/L with CV method was obtained and the detection limit was found as 4.3 × 10-5 mol/L.
