Avaliação de potencialidades e aplicações de espectrômetros com plasma acoplado indutivamente em análises químicas.
Resumen
This work is divided in two main parts. In the first one, the operating
conditions of a radially inductively coupled plasma optical emission spectrometry (ICP
OES) was evaluated in soil and vegetable materials analysis. A factorial design was
performed to systematic evaluation of the equipment operating conditions, being
established: 1.05 kW power, 0.6 L min-1 flow gas nebulization and 8 mm observation
height as operating conditions to Ca, Fe, K, Mg, Mn, Na, P, and Zn determination in
the studied samples, certified materials (NIST, Peach Leaves and Corn Bran), digested
in different oxidant media. The recoveries of Cu, Fe, Mn, and Zn in soil extracts (IAC
274 and NIST San Joaquim Soil) were also evaluated in the same established
conditions. A protocol was established for use of the equipment in routine analysis. In
the second part of this work, the bioavailability of iron-proteins in different crude and
processed foods was evaluated. Two different media were used to metalloprotein
extraction: Tris buffer 5,0x10-3 mol L-1 and simulated gastric fluid. An inductively
coupled plasma mass spectrometer (ICP-MS) was used to determine Fe in the extract
solutions and a size exclusion column (SEC) coupled to UV-ICP-MS detectors was
used to metalloprotein speciation. The results indicated that the cooking caused
significant changes in the amounts of Fe bond to proteins from beefs and seaweeds,
although the elements were still bioavailables.