Determination of metals in Brazilian soils by inductively coupled plasma mass spectrometry.

The concentration of metals in Brazilian soil under no-tillage (NT) and an area under native vegetation (NV) was determined by inductively coupled plasma mass spectrometry. The applied method was based on microwave-assisted acid digestion using HNO3, HCl, H2O2, and HF. The accuracy of the method was evaluated by analyzing two certified reference materials (BCR-142 and RS-3).

Minerals consumption by Acetobacter xylinum on cultivation medium on coconut water.

The objective of this work is to verifying the consume of the minerals K, Na, Fe, Mg, P, S-SO4 (-2), B, N Total Kjedahl (NTK), NO3 (-)-N, and NH4 (+)-N in the production of bacterial cellulose by Acetobacter xylinum, according to the medium and the manner of cultivation. The fermentative process was in ripe and green coconut water. K and Na were determined by flame emission photometry, Mg and Fe by atomic absorption spectrophotometry, P by molecular absorption spectrophotometry, S-SO4 (-2) by barium sulphate turbidimetry, B by Azomethin-H method, NTK by Kjeldahl method, N-NO3 (-) and N-NH4 (+) by vapor distillation with magnesium oxide and Devarda's alloy, respectively.