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A protocol for blood sampling, storage and digestion for subsequent determination of Br, Cl and I by inductively coupled plasma mass spectrometry (ICP-MS) was proposed. The blood sampling was perfo...

A novel system for sample digestion was proposed based on microwave-induced combustion in disposable vessels (MIC-DV) for trace elements determination by inductively coupled plasma optical emission spectrometry (ICP-OES). As a proof of concept, botanical samples were digested by MIC-DV for further determination of Al, Cr, Cu, Fe, Mn, Sr, and Zn. The system consists of a quartz holder (a modified version of conventional MIC) placed inside disposable polypropylene (PP) vessels. The quartz holder was carefully designed to avoid excessive heating and damaging of the vessel walls. For the combustion, the PP vessels containing the quartz holder and sample were placed in a specially designed metallic rotor that prevents the heating of absorbing solution and allows the use of a domestic microwave oven for sample ignition. After combustion, the digestion vessel was shaken to ensure the analytes' absorption. The single-vessel principle was fulfilled, since no further dilution or liquid transfer was required and the same PP vessel used for digestion allowed solution storage until element determination. The influences of absorbing solution (diluted HNO3 and water) and sample mass (10 to 30 mg) were evaluated. By using the proposed MIC-DV system, low volumes of diluted absorbing solutions (5 mL of 1 mol L-1 HNO3) were possible, allowing the use of low reagent amounts and low energy consumption, since microwave irradiation is used only for sample ignition. The agreement with certified values ranged from 92 to 108% for all analytes, whereas the precision was below 15%. All of these advantages, combined with the use of low-cost disposable vessels and instrumentation, make MIC-DV suitable to be used for research and routine analysis.

There are some genes associated to the risk of chronic diseases that present potential nutrigenetic response, such as the human manganese-dependent superoxide dismutase gene (Val16Ala-SOD2, rs4880) for which homozygous genotypes (VV and AA) are associated with higher basal superoxide (S) and hydrogen peroxide (HP) levels, respectively. It is possible that the VV- and AA-imbalance could be attenuated by selenium(Se)-rich foods such as Brazil nut (BN). To test this hypothesis, we conducted an in vitro protocol triggering a chemical S-HP imbalance by exposure of dermal fibroblast cells (HFF-1) to paraquat, which generates high S levels (VV-like treatment) and porphyrin (MnTBAP), which generates high HP levels (AA-like treatment). Modulation of cell growth and pro-oxidative and antioxidant markers were evaluated. BN aqueous extract (BNAE) most effective concentration which increased cell growth and decreased oxidative metabolism indicators of imbalanced cells was 75 ng Se/mL. However, this effect was not directly affected by the S-HP imbalance: in AA-SOD2-like cells, thioredoxin reductase (TrxR-1) gene was upregulated and in VV-SOD2-like cells an upregulation of glutathione peroxidase (GPx-1) gene expression was observed, however, this regulation occured in a homeostatic manner. These results suggest that BNAE was able to minimize negative effects in both directions of the S-HP imbalance, by modulation of different oxidative-metabolic pathways.

In this work, two microwave-assisted sample preparation methods based on combustion and ultraviolet digestion for futher determination of Br, Cl, and I in blood by inductively coupled plasma mass spectrometry were proposed. For microwave-induced combustion (MIC), blood was spotted on square pieces of Munktell TFN paper, and water and diluted NH4OH were evaluated as absorbing solutions. The stability of the analytes in the spotted blood was also evaluated. During 90 days, no changes of halogen content were observed for samples (with and without anticoagulant) on paper stored in a desiccator at 20 ± 5 °C. Whole blood was also digested by microwave-assisted ultraviolet digestion (MAD-UV). Some parameters as the volume of HNO3 solution, the influence of H2O2, and the effect of UV radiation were investigated. The interferences caused by C and K on halogen determination were carefully investigated. The results for MIC and MAD-UV and Br, Cl and I determination by ICP-MS presented no difference. The accuracy of MIC and MAD-UV was also evaluated by analyte spike with reference solutions of Br, Cl and I using inorganic species and also organic I standard (T4-levothyroxine). For both methods, recoveries were 94 and 108% for Br, 96 and 103% for Cl, and 104 and 97% for I. In case of organic I, recoveries were 99 and 111% for MIC and MAD-UV, respectively. The limits of quantification for MIC and MAD-UV after ICP-MS determination were 0.06 and 0.04 μg g−1 for Br, 14 and 30 μg g−1 for Cl and 12 and 8 ng g−1 for I, respectively. The proposed methods provide a suitable digestion approach, assuring safety and high digestion efficiency for further halogen determination in blood, with the possibility to use in clinical analysis.