A determinação da uréia em fertilizantes, pelo método volumétrico da urease

Abstract

The urease method for urea determination in fertilizers is studied. The procedure consists in the transformation of the urea in ammonis, which is neutralized by an excess of sulfuric acid. The excess of sulfuric acid is titrated and the concentration of urea calculated. The fessibility of the method in the determination of urea in four different mixtures of fertilizers (containing nitric nitrogen, ammoniacal nitrogen, superphosphate and different amounts of urea) was tested. The proposed method showed to have good precision and accuracy besides beeing faster than others commonly used methods.