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MAGNETIC IONIC LIQUID-BASED MICROEXTRACTION AND PRECONCENTRATION TECHNIQUE FOR ARSENIC SPECIATION ANALISYS BY ELECTROTHERMAL ATOMIC ABSORPTION SPECTROMETRY
OVIEDO, MARIA NATALIA; FIORENTINI, EMILIANO; WUILLOUD, RODOLFO G.
Simposio; 15th RIO SYMPOSIUM ON ATOMIC SPECTROMETRY; 2019
Universidad Nacional de Cuyo
Arsenic is a highly toxic metalloid that can be present in low concentrations in water, soil, air and food. Its toxicity in environmental and biological systems is strongly dependant on chemical nature of its species1. It is well known that the inorganic species of As are more toxic than organic arsenicals, and the toxicity of As(III) is greater than As(V). Thus, speciation analysis of arsenic becomes highly necessary2. The natural concentration of total As in surface water is usually less than 10 µg L-1. On the other hand, the concentration of the different species of As are of the order of ng L-1. However, these low concentrations are not compatible with the limits of detection (LOD) reached by some detectors based on atomic spectrometry. Therefore, the development of sensitive analytical methodologies for preconcentration and speciation of As at trace levels is required. Ionic liquids (ILs) have been widely used as an extractant solvent in liquid-liquid microextraction techniques (LLME). Recently, a new family of ILs known as magnetic ionic liquids (MILs) has become the subject of interest in several analytical applications. MILs strongly respond to external magnetic fields, apart from possessing the unique and tuneable physicochemical properties of ILs3. In the present work, a novel LLME technique using the MIL trihexyl(tetradecyl)phosphonium hexachlorodisprosiate ([P6,6,6,14]3DyCl6) (MIL1) was developed for selective separation of As(III) with ammonium pyrollidine dithiocarbamate (APDC) as complexing agent. Then, the extraction and preconcentration of As(V) present in the aqueous phase was performed using the MIL trihexyl(tetradecyl)phosphonium tetrachloroferrate ([P6,6,6,14]FeCl4) (MIL2) by electrothermal atomic absorption spectrometry (ETAAS). This method consists in adjusting the acidity of aqueous samples to a concentration of 1 mol L -1 HCl, followed by the extraction of As(V) with the MIL2. After the vortex stage, the MIL2 was collected with the use of a magnetic rod, diluted in CHCl3 and an aliquot of the eluate was injected into the graphite furnace of ETAAS for As determination. Under optimal experimental conditions, an extraction efficiency of 92% was obtained, an LOD of 15ng L-1 of As(V) and a relative standard deviation (RSD) of 3.6% (for a As(V) solution of 100μg L-1 and n = 10). The proposed methodology was successfully applied to aqueous samples. References  Monasterio R.P., Wuilloud R.G., J. Anal. At. Spectrom. 25 (2010) 1485?1490  Wang X., Xu G., Chen P., Liu X., Fang Y., Yang S. and Wang G., RSC Adv. 6 (2016) 110247-110254  Fiorentini E.F., Escudero L.B., Wuilloud R.G., Anal. Bioanal. Chem. 410 (2018) 4715-4723.