Determinação do teor total e do teor solúvel, em diversas soluções, do cobre do solo

Abstract

Copper in soils, both total and soluble in several extracting solutions, was determined by the sodium diethyldithiocarbamate colorimetric method. For the determination of total copper, 250 mg samples of 5 differents soils from the state of São Paulo, were attacked with HC1O4, HF and HNO3 mixture. The amounts of total copper found varied from 23 to 126 ppm. The soluble copper was extracted by shaking the soils with 0,05 and 0.10 N HCl, 1% disodium EDTA, and 0,10 N CH3COOH solutions. For the extraction with HCl solutions, 2.5 and 5.0 g of soil were shaken with 50 ml of HCl solutions for 10, 15 and 30 minutes. The amounts of copper found were from 0.5 to 14.6 ppm for the 0.10N HC1 and from 0.3 to 10.2 ppm for the 0.05 N HCl solutions. The extrations with the disodium EDTA and CH3COOH solutions, were made by shaking 5.0 g of soil with 50 ml of extracting solution for 10, 15 and 30 minutes. The amounts of soluble copper were from 0.8 to 15.0 ppm for the disodium. EDTA solution, and from 0.0 to 0.5 ppm for the CH3COOH solution.