INVESTIGATIONS ON ADSORPTION POTENTIOMETRY .4. DERIVATIVE ADSORPTION CHRONOPOTENTIOMETRY OF THE BISMUTH-2-(5'-BROMO-2'-PYRIDYLAZO)-5-DIETHYLAMINOPHENOL SYSTEM

Derivative adsorption chronopotentiometry of the bismuth complex with 2-(5'-bromo-2'-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) has been described. The theory of derivative adsorption chronopotentiometry for the complex system and the method of determination of the composition, the conditional stability constant, as well as the number of electrons transferred by the electroactive complex adsorbed on the surface of the electrode have been discussed. In 0.025 mol/L NaOH, the linear range of the method is 2 x 10(-9) to 1.1 x 10(-7) mol/L for the preconcentration time of 120 seconds. This method has been used to determine the bismuth content in food.