INVESTIGATIONS ON ADSORPTION POTENTIOMETRY .5. DERIVATIVE ADSORPTION CHRONOPOTENTIOMETRY OF BERYLLIUM(II)-4-[(4-DIETHYLAMINO-2-HYDROXYPHENYL)-AZO]-5-HYDROXY-NAPHTHALENE-2,7-DISURPHONIC ACID SYSTEM

An electroanalytical methood, based on derivative chronopotentiometry of the complex of beryllium(II) with 4-[(4-diethylamino-2-hydroxyphenyl)-azo]-5-hydroxy-naphthalene-2,7-disurphonic acid (Beryllon III) accumulated adsorptively on the surface of a hanging mercury drop electrode, has been developed for determining trace beryllium in food. The dependences of the peak height on the dt/dE vs. E curve on the preconcentration time, preconcentration potential and the constant reducing current are discussed. In 0.15 mol/l NH5 + 0.05 mol/l NH4Cl, 4 x 10(7) mol/l Beryllon III, and at a preconcentration potential of -0.30 V (vs. SCE), the limit of detection and linear range are 1 x 10(-10) mol/l and 3 x 10(-10) -2 x 10(-7) mol/l, respectively. The relative standard error of the method is 2.3% for 6 x 10(-5) mol/l Be(II). The method was applied to samples of food. The electrode process has been discussed.