A new method for the determination of dopamine (DA) and paracetamol (PCT), based on the azo “coupling reaction with oxidized 2,4-dinitrophenylhydrazine (DNPH), has been established. This method was based on the fact that in the HCl buffer solution, potassium ioadate oxidized 2,4- dinitrophenylhydrazine to form the diazonium chloride at 0e5oC and then the diazonium ion reacted with the phenolic compounds to form azo-compounds |