Determina？？o das várias formas de fósforo em tortas de filtro rotativo

this paper describes analytical methods for determining the various phosphorus fractions in filter cake. these fractions can be classified as to their solubility in several extractants: water; 2% citric acid; neutral ammonium citrate; 0,5 n sulfuric acid. all procedures employed colorimetric methods, using the reagents according to the needed sensitivity. the metodology for the determination of total phosphorus after a dry solubilization procedure is described as well as the methodology for organic phosphorus determination. the inorganic phosphorus predominate in the samples with a range of 2,3 to 0,8%, depending on the origin and harvesting period. the best procedure was the analysis of the cake in its natural condition (moist cake) using the extraction by 2% citric acid solution.