Materials containing zinc can erroneously be considered fertilizer materials due to the inadequate official procedure adopted to evaluate zinc content. The purpose of this paper was to develop an analytical procedure that permits to recognize zinc fertilizer materials. The following extractor solutions were used: ammonium chloride 2M, 1,5M and 1M, ammonium citrate of d = 1.09 and pH = 7.0, that is, the same solution used to evaluate phosphorus in fertilizers, in the original concentration and in the dilutions (1 + 1), (1 + 3), (1 + 9), and citric acid 2%. The extraction technique involved agitation or boiling of sample with extractor solutions. Results showed that ammonium citrate solution in the (1 + 9) dilution was the best to characterize water insoluble zinc in the fertilizer materials. Products not considered fertilizers with insoluble zinc presented relatively high percentage of total copper, lead and cadmium.
fertilizer materials; zinc