Evaluation of Techniques for Determination of Molybdenum in Sugarcane Leaves

摘要

In crops of the sugarcane, the concentrations of molybdenum (Mo) in the leaves are generally lower than 0.3 mg Mo kg~(-1). These low concentrations have resulted in limitations in the methods and instruments that can be used for these analyses. The objective of this study was to evaluate three different techniques to determine the concentration of Mo in sugarcane leaves sampled in the principal sugarcane-producing areas in Brazil. Two spectrometric techniques were evaluated by using ICP-EAS (Inductively Coupled Plasma-Emission Automated System) and DCP-MEAS (Direct Coupled Plasma-Multiple Emission Automated System) and a colorimetric technique of the reaction between potassium iodide and hydrogen peroxide (KI-H_2O_2). The techniques ICP-EAS and KI-H_2O_2 produced results of satisfactory accuracy and precision, whereas the DCP-MEAS consistently overestimated the Mo concentrations in cane leaves. The KI-H_2O_2 technique showed sensitivity 5 times greater than the ICP-EAS, with minimum detection limits of 0.1 and O.SmgMokg~(-1), respectively.