RESUMO
The soils developed under High Altitude Rocky Complexes in Brazil are generally of very low chemical fertility, with low base saturation and high exchangeable aluminium concentration. This stressful condition imposes evolutionary pressures that lead to ecological success of plant species that are able to tolerate or accumulate high amounts of aluminium. Several analytical methods are currently available for elemental mapping of biological structures, such as micro-X-ray fluorescence (µ-EDX) and histochemical tests. The aim of this study was to combine µ-EDX analysis and histochemical tests to quantify aluminium in plants from High Altitude Rocky Complexes, identifying the main sites for Al-accumulation. Among the studied species, five showed total Al concentration higher than 1000 mg kg-1. The main Al-hyperaccumulator plants, Lavoisiera pectinata, Lycopodium clavatum and Trembleya parviflora presented positive reactions in the histochemical tests using Chrome Azurol and Aluminon. Strong positive correlations were observed between the total Al concentrations and data obtained by µ-EDX analysis. The µ-EDX analysis is a potential tool to map and quantify Al in hyperaccumulator species, and a valuable technique due to its non-destructive capacity. Histochemical tests can be helpful to indicate the accumulation pattern of samples before they are submitted for further µ-EDX scrutiny.
Assuntos
Altitude , Alumínio/análise , Plantas/química , Brasil , Fluorescência , Histocitoquímica , Espectrometria por Raios XRESUMO
The combined use of internal standardization with collision and reaction interface in an inductively coupled plasma quadrupole mass spectrometer (ICP-QMS-CRI) was evaluated. The behavior of several elements (Ba, Cd, Co, Cr, Cu, Li, Mn, Mo, Pb, Sb, V and Zn) was studied by introducing H(2) or He through the skimmer and sampler cones of the CRI device and by using In, Rh and Sc as internal standards. Certified reference material of trace elements in water (NIST 1643e) was used to evaluate the performance of the method. A vinegar sample and mixed food diet standard reference material were directly introduced into the equipment as complex matrices for Cr and V determinations. Improvements in accuracy and precision were attained combining both strategies. The introduction of H(2) through the skimmer cone was the best way to overcome polyatomic ions formation and to improve SBR and BEC values for several elements. The use of Sc as internal standard improved the performance of ICP-QMS-CRI.