According to the methodology proposed in this work, the
solubilization of meat samples in alkaline medium shows several
advantages: minimal sample manipulation; small amounts of
reagent (resulting in a small dilution and small amount of
residues); no heating necessary for the solubilization of the
samples; rapidity. However, the meat samples treated with TMAH
resulted in opaque solutions, indicating a slurry formation, which
can lead to instability and matrix effects in the plasma (Brenner
and Zander, 2000) even though this kind of approach proved to be
much simpler than the reference method recommended by the
Brazilian Ministry of Agriculture for the determination of trace
metals in muscle, liver and kidney.
For the sake of comparison, this official methodology uses
approximately 2 g of fresh samples in the presence of 5 mL of
concentrated nitric acid heated in a digester block to 90 8C for 1 h,
with soft agitation to avoid foam formation. After keeping in this
medium overnight, 2 mL of H2O2 is added to the samples and the
mixture is heated to 90 8C for 1 h. After cooling, the volume is
completed to 15 mL with water for subsequent analysis (PNCR,
2011). Thus, it is possible to observe that this traditional technique
is time consuming, requires large amounts of reagents and
generates hazardous waste. In addition, it might contaminate
the sample with the presence of the analytes. In this work the
treatment with TMAH led to a complete sample solubilization, at
least visually, and the obtained sample solutions did not clog the
nebulization system when operating under the conditions shown
in Table 1. Therefore, a preliminary study of the optimization of
instrumental parameters of the ICP OES instrument, regarding
plasma robustness and delay time, was necessary in order to
minimize possible interferences related to matrix effects