Microwave-based strategies for sample preparation and halogen determination in blood using ICP-MS.

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.

Ilex Paraguariensis exposition to As and Cd in a closed soilless system.

The exposition of mate (Ilex Paraguariensis A. St.-Hil.) to As and Cd was investigated in plants derived from young mini-cuttings. Mate plants were cultivated in a closed soilless system, composed of coarse sand as substrate and flood fertirrigation. Plantlets were fertirrigated with nutritive solution and As and Cd solutions were added to the nutritive solution in the final concentration of 8 and 17 mg L-1 (As) and of 17 and 33 mg L-1 (Cd) during 14 days. Results show that stem diameter and Dickson quality index (DQI) variables could not be used as a potential indicator of accumulation of As and Cd. The shoot height, number of leaves and chlorophyll index are variables easy and quick to measure and they can be used as parameters to evaluate the stress caused in mate plants cultivation in a closed soilless system. The highest concentration of As and Cd was in roots of plants. Beyond the roots, As and Cd also can be translocated to the leaves achieving high concentrations. In addition, leaves from the treated mate plants were submitted to a hot infusion extraction in order to simulate the traditional beverage and As and Cd were determined in the infusion. Regarding to the infusion procedure, considerable As and Cd amounts were extracted from the leaves leading to conclude that this way of consumption can be an important source of toxic elements for the human diet.

Determination of cadmium and lead at sub-ppt level in soft drinks: An efficient combination between dispersive liquid-liquid microextraction and graphite furnace atomic absorption spectrometry.

A DLLME method for extraction and preconcentration of Cd and Pb from soft drinks and further determination by GF AAS was developed. Important parameters of DLLME such as the type and volume of dispersive and extraction solvents, concentration of DDTC (complexing agent) and pH were evaluated. Better results were obtained using 500µL of acetone for Cd and 700µL of acetonitrile for Pb as dispersive solvents, 60µL of CCl4 as extraction solvent for both analytes and 500µL of 1.5% DDTC solution. Accuracy was evaluated by recovery assays and ranged from 91 to 113% for Cd and from 95 to 108% for Pb, with RSD below 10 and 7%, respectively. The LODs were 0.006 and 0.072ngL-1 for Cd and Pb, respectively. The optimized method was applied for the determination of Cd and Pb in soft drinks with different brands and flavours.