Facultad de Ciencias Exactas y Naturales

Publicaciones 2019

Determination of As in honey samples by magnetic ionic liquid-based dispersive liquid-liquid microextraction and electrothermal atomic absorption spectrometry

Fiorentini, EF; Canizo, BV; Wuilloud, RG. Talanta, 2019, 198, 146-153.

A dispersive liquid-liquid microextraction (DLLME) method was developed based on the application of a magnetic ionic liquid (MIL) used as extractant phase for trace As determination in honey samples by electrothermal atomic absorption spectrometry (ETAAS). The procedure was simple, efficient and did not require a centrifugation stage. The As(III) species was preconcentrated by chelation with ammonium diethyldithiophosphate under acidic conditions at 3 mol L-1 HCl, followed by the extraction of the chelated analyte with the MIL trihexyl(tetradecyl)phosphonium tetrachloroferrate (III) ([P-6,P-6,P-6,P-14]FeCl4) and acetonitrile as dispersant. The MIL phase containing the analyte was separated simply by a magnet. The collected aliquot of the MIL phase was injected directly into the graphite furnace of ETAAS for As determination. Under optimal experimental conditions, an extraction efficiency of 99% and a sensitivity enhancement factor of 110 were obtained. The limit of detection was 12 ng L-1 As and the relative standard deviation 3.9% (at 1 mu g L-1 As and n = 10), calculated from the peak height of the absorbance signals. The linear range obtained was 0.02-5.0 mu g L-1. This work reports the first application of the MIL [P-6,P-6,P-6,P-14]FeCl4 along with the DLLME technique for the determination of As in honeys.

Plasmon-induced hot-carrier generation differences in gold and silver nanoclusters

Douglas-Gallardo, OA; Berdakin, M; Frauenheim, T; Sanchez, CG. Nanoscale, 2019, 11, 8604-8615.

In the last thirty years, the study of plasmonic properties of noble metal nanostructures has become a very dynamic research area. The design and manipulation of matter in the nanometric scale demands a deep understanding of the underlying physico-chemical processes that operate in this size regimen. Here, a fully atomistic study of the spectroscopic and photodynamic properties of different icosahedral silver and gold nanoclusters has been carried out by using a Time-Dependent Density Functional Tight-Binding (TD-DFTB) model. The optical absorption spectra of different icosahedral silver and gold nanoclusters of diameters between 1 and 4 nanometers have been simulated. Furthermore, the energy absorption process has been quantified by means of calculating a fully quantum absorption cross-section using the information contained in the reduced single-electron density matrix. This approach allows us take into account the quantum confinement effects dominating in this size regime. Likewise, the plasmon-induced hot-carrier generation process under laser illumination has been explored from a fully dynamical perspective. We have found noticeable differences in the energy absorption mechanisms and the plasmon-induced hot-carrier generation process in both metals which can be explained by their respective electronic structures. These differences can be attributed to the existence of ultra-fast electronic dissipation channels in gold nanoclusters that are absent in silver nanoclusters. To the best of our knowledge, this is the first report that addresses this topic from a real time fully atomistic time-dependent approach.