DETERMINATION OF ULTRA-TRACE VANADIUM BY 1.5TH AND 2.5TH ORDER DERIVATIVE ADSORPTION VOLTAMMETRY

On the basis of the adsorptive characteristics of the vanadium(V) complex with 2-(5'-bromo-2'-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) at a mercury electrode in HAc+NaAc (pH = 4.5) and using the 1.5th and 2.5th order derivative technique, a very sensitive 1.5th and 2.5th order derivative adsorption voltammetry for the determination of ultra-trace vanadium is developed. The limit of detection and the linear range of the method are 2.5×10-11 mol/1 and 5×10-10-2×10-7 mol/1, respectively. The method has been applied successfully to the determination of vanadium in samples of tap water. The equations of the 1.5th and 2.5th order derivative of the current with respect to time are discussed and verified experimentally for the V(V)-5-Br-PADAP system. © 1990.