Dispersive liquid-liquid microextraction as a preconcentration alternative to increase ETAAS sensitivity in the analysis of molybdenum in bovine meat and pasture samples.

A new procedure combining dispersive liquid-liquid microextraction and electrothermal atomic absorption spectrometry was proposed for the determination of molybdenum in plants and animal tissue. The optimized conditions for the microextraction procedure were: 150 µL of 0.3 mol L-1 potassium ethyl xanthate (pH 1.4) and 1000 µL of acetonitrile and 50 µL of carbon tetrachloride as dispersive and extractant solvent, respectively. A limit of detection of 0.03 µg kg-1 and a limit of quantification of 0.11 µg kg-1, as well as an enrichment factor of 200, were achieved employing this procedure. Standard reference materials were used for trueness and precision evaluation. No significant differences were found at the 95% confidence level between certified and obtained values, and the precision expressed as repeatability (sr %) was 4.1% for animal tissue and 4.7% for plant material. The method was successfully applied for the determination of Mo in bovine meat and pasture samples from different livestock establishments.

Trypanosoma cruzi biochemical changes and cell death induced by an organometallic platinum-based compound.

Chagas disease is an endemic illness in Latin America caused by the parasite Trypanosoma cruzi. Current chemotherapies are old and inadequate, and the emergence of drug-resistant strains underscores the need of new drugs. Platinum-based complexes have been shown to be a promising approach against parasitic diseases. In this work, the effect of 1,1'-bis(diphenylphosphino)ferrocene pyridine-2-thiolate-1-oxide Pt(II) hexafluorophosphate, Pt-dppf-mpo, was studied on T. cruzi. A promising antitrypanosomal activity was determined for the CL Brener strain with a low cytotoxicity determined using in vitro-cultured mammal cells. The compound uptake in parasites treated with concentrations of 1× and 10× the IC50 value reached ~75% and 19%, respectively. Pt-dppf-mpo induced necrosis after 24 hr of parasite incubation. This event was preceded by depolarization of mitochondrial membrane potential. Cell vitality assays showed high esterase activity in treated parasites. However, despite this increase in metabolic activity, treated epimastigotes showed rounded morphology and loss of flagellum with a reduction in mobility as compound concentration and/or time of incubation was increased. At last, we demonstrate that Pt-dppf-mpo incubation also affects the trypomastigote infection process as well as the infection persistence evaluated as the number of amastigotes per cell in a dose-dependent manner.