Evaluation of micro-energy dispersive X-ray fluorescence spectrometry for the analysis of plant materials

An analytical procedure relying on micro-energy dispersive X-ray fluorescence spectrometry (mu-EDX) was evaluated for the quantitative determination of macro-, micronutrients and beneficial elements in pressed pellets of plant materials. For testing purposes, leaves from 23 varieties of sugar cane, previously analyzed by validated reference methods, based on wet decomposition procedures followed by ICP OES measurements were used. Linear correlations between analyte mass fractions in the tested samples and the corresponding mu-EDX intensities were obtained for P, K, Ca, S, Fe, Mn and Si with regression coefficients ranging from 0.9501 to 0.9933. Furthermore, the coefficients of variation of results in the 0.3 to 16% range (n = 3 sampling lines, 30 sampling sites per line), the spatial resolution of 50 mu m per site and the suitable detection limits for these analytes were additional features that demonstrated the performance of the proposed procedure as a useful tool for plant nutrient diagnosis. In addition, the results also indicate that mu-EDX can be recommended as a cross-validation method for analysis of plant materials, owing to its inherent non-destructive capability and, particularly, when dealing with analytes' micro-heterogeneity evaluation within the samples.