Nouvelle méthode de dosage automatique de substances oxydantes ou réductrices par potentiométrie différen-tielle: Partie III: Application à l'analyse en flux continu (lac-tose par cérimétrie)

The development of an automatic analyzer for the measurement of redox systems by differential potentiometry in continuous flow is described. Variations in several instrumental parameters were studied. The analyzer was applied to the determination of a carbohydrate (lactose) with cerium(IV) solution, first in distilled water and then in milk. The results obtained in examining the influence of different experimental conditions, and the linearity, sensitivity and the specificity of the method, confirmed the previous results obtained manually. However. cerium(IV) proved to be too strong an oxidant for the measurement of lactose in milk. Cerium(IV) increased the sensitivity of the method, but was insufficiently selective: neither dialysis nor precipitation with trichloracetic acid eliminated quantitatively all interferences. even at low temperatures. Milder oxidants are necessary.