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Padro J.M.,Laboratorio Of Separaciones Analiticas | Ponzinibbio A.,National University of La Plata | Mesa L.B.A.,Laboratorio Of Separaciones Analiticas | Reta M.,Laboratorio Of Separaciones Analiticas
Analytical and Bioanalytical Chemistry

The partition coefficients, PIL/w, for different probe molecules as well as for compounds of biological interest between the room-temperature ionic liquids (RTILs) 1-butyl-3-methylimidazolium hexafluorophosphate, [BMIM][PF6], 1-hexyl-3-methylimidazolium hexafluorophosphate, [HMIM][PF6], 1-octyl-3-methylimidazolium tetrafluoroborate, [OMIM][BF4] and water were accurately measured. [BMIM][PF 6] and [OMIM][BF4] were synthesized by adapting a procedure from the literature to a simpler, single-vessel and faster methodology, with a much lesser consumption of organic solvent. We employed the solvation-parameter model to elucidate the general chemical interactions involved in RTIL/water partitioning. With this purpose, we have selected different solute descriptor parameters that measure polarity, polarizability, hydrogen-bond-donor and hydrogen-bond-acceptor interactions, and cavity formation for a set of specifically selected probe molecules (the training set). The obtained multiparametric equations were used to predict the partition coefficients for compounds not present in the training set (the test set), most being of biological interest. Partial solubility of the ionic liquid in water (and water into the ionic liquid) was taken into account to explain the obtained results. This fact has not been deeply considered up to date. Solute descriptors were obtained from the literature, when available, or else calculated through commercial software. An excellent agreement between calculated and experimental log PIL/w values was obtained, which demonstrated that the resulting multiparametric equations are robust and allow predicting partitioning for any organic molecule in the biphasic systems studied. © Springer-Verlag 2011. Source

Padro J.M.,Laboratorio Of Separaciones Analiticas | Marson M.E.,National University of La Plata | Mastrantonio G.E.,National University of La Plata | Altcheh J.,Parasitologia Chagas. Hospital de Ninos Ricardo Gutierrez | And 2 more authors.

Dispersive ionic liquid-liquid microextraction combined with liquid chromatography and UV detection was used for the determination of two antichagasic drugs in human plasma: nifurtimox and benznidazole. The effects of experimental parameters on extraction efficiency - the type and volume of ionic liquid and disperser solvent, pH, nature and concentration of salt, and the time for centrifugation and extraction - were investigated and optimized. Matrix effects were detected and thus the standard addition method was used for quantification. This microextraction procedure yielded significant improvements over those previously reported in the literature and has several advantages, including high inter-day reproducibility (relative standard deviation=1.02% and 3.66% for nifurtimox and benznidazole, respectively), extremely low detection limits (15.7 ng mL-1 and 26.5 ng mL-1 for nifurtimox and benznidazole, respectively), and minimal amounts of sample and extraction solvent required. Recoveries were high (98.0% and 79.8% for nifurtimox and benznidazole, respectively). The proposed methodology offers the advantage of highly satisfactory performance in addition to being inexpensive, simple, and fast in the extraction and preconcentration of these antichagasic drugs from human-plasma samples, with these characteristics being consistent with the practicability requirements in current clinical research or within the context of therapeutic monitoring. © 2013 Elsevier B.V. Source

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