Overall, the combination of two soils with application of four different [sup.33]P treatments resulted in eight treatments being tested in triplicate (n = 3) for the Ferralsol and in quintuplicate (n = 5) for the Luvisol.
The filling angle of repose ([[theta].sub.f]) was determined by quintuplicate using a hollow plastic cylinder open at both ends with a diameter of 14 cm and height of 50 cm.
The extracted solution was filtered (12 [micro]M) and the metals were determined by optical emission spectrometers with inductively coupled plasma (ICP-OES) in quintuplicate following standards methods.
To corroborate the repeatability of the chromatographic procedure, the 2D-TLCs were performed by quintuplicate obtaining repetitive results, evaluated by their respective [R.sub.F] values.
The IB content determinations were carried out in quintuplicate. The nanoparticles were allowed to settle and the supernatant liquid was removed; then the particles were dried in an oven (NAPCO Vacuum Oven Model 5831) at a temperature of 35[degrees]C and vacuum (pressure of 25 in Hg) until constant weight.