Resumo:
An analytical procedure for the determination of small concentrations of copper and zinc by 2-carboxy-2'hydroxy-5'-sulfoiormazylbenzene (Zincon) method in leaf samples is described. Copper and zinc are measured colorimetrically after they are separated from other elements by extraction with dithizone from a solution prepared by wet digestion of one-gram sample of dry plant material with a mixture of HN03—H2S04—HClO4. The method as outlined here is sufficiently sensitive and accurate in the analysis of leaves for diagnosis of nutritional deficiencies of these elements, being suitable for concentrations of 5 to 30 ppm in plant material. Color is formed at a reagent concentration of 4.5 x 10—5M and a wave length of 590mm is used for analytical measurements. Analyses by the spectrophotometry procedure reported are faster and the results compare with the Polarographic method.
