Determinação de cobre em solos, fungicidas e material vegetal
Palavras-chave:
teor cobre, elemento químico, métodos espectrométricos, solução reagente, análise químicaResumo
This paper deals with a microanalytical adaptation to the technique developed by CHENG and BRAY (3) for copper analysis. The adaptation was developed and tested on soils, fungicides and bean seeds as well as on vegetative parts of the bean plant.
The reagent, diethyldithiocarbamate, after reaction with copper, was extracted with carbon tetrachloride. Measurements were performed at 440 and 436 nm according to the photometer used. Interference was probed with 13 types of cations. Only bismuth showed some reasonable degree of interference at these wavelengths: its optical density was 63 times lower on weight basis than that of copper.
The following specific results were found:
a. Soils, tested on 19 different samples, showed values between traces and 6,0 ppm.
b. Fungicides, represented by 6 samples, confirmed the values stated by the manufacturers. The mean variation coefficient was of 3.1%.
c. The copper amounts of 173 samples of varied between 2.8 and 23.5 ppm, depending on the part of the plant and the vegetative stage. The mean difference found among 79 couples of repetition was of 86 ppm.
Referências
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