X-RAY-FLUORESCENCE ANALYSIS OF SMALL LEAF SAMPLES MIXED WITH CELLULOSE OR BORIC-ACID

X-ray fluorescence (XRF) is an effective and rapid technique for the analysis of many mineral elements in plant tissue. Plant samples sometimes are too small to make good pellets and to provide good XRF analyses. Leaf tissue was mixed with cellulose or boric acid at different ratios to assess whether pellets from these mixtures could be analyzed by XRF and to determine the effects of these inert substances on analysis of Al, Ca, Cl, Cu, Fe, K, Mg, Mn, P, S, Si, and Zn. Concentrations of all elements decreased linearly at all leaf/cellulose ratios. Concentrations of Mn, Fe, Zn, and Cu decreased linearly at all leaf/boric acid ratios, but concentrations of the other elements decreased linearly only when leaf/boric acid ratios were above about 40/60, and decreases in concentration of these other elements were more pronounced at leaf/boric acid ratios below 40/60. Concentrations of P, S, Cl, K, Mg, Ca, Si, and Al were higher in leaf/boric acid than in leaf/cellulose pellets, and similar concentrations were noted for Cu, Mn, Fe, and Zn in both kinds of pellets. Mechanically shaking cellulose with leaf tissue generally resulted in higher mineral element concentrations than if samples were mixed by hand. Cellulose would be the preferred inert substance to mix with plant samples if plant samples are below approximately 40 mg in size. Small samples of plant tissue can effectively be analyzed by XRF when mixed with cellulose or boric acid.