Magnetic ionic liquid-based microextraction and preconcentration technique coupled to electrothermal atomic absorption spectrometry for trace chromium determination in drinking water samples

EMILIANO F. FIORENTINI; MARIA N. OVIEDO; RODOLFO G. WUILLOUD

Congreso; CSI2019; 2021

In the present work, a novel LLME technique based on the formation of ion pairs between the MIL trihexyl(tetradecyl)phosphonium tetrachloroferrate ([P6,6,6,14]FeCl4) and the anion [Cr(H2O)2Cl4]- was developed for the preconcentration and determination of Cr by electrothermal atomic absorption spectrometry (ETAAS). The resulting method consisted in adjusting the acidity of water samples to a concentration of 1 mol L -1 HCl, followed by the extraction of Cr with ion pair formation with the MIL, the use of acetonitrile as a dispersant and vortexing. The MIL 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 Cr determination. Under optimal experimental conditions, an extraction efficiency of 95% was obtained, an LOD of 41 ng L -1 of Cr and a relative standard deviation (RSD) of 3.2% (for a Cr solution of 1 µg L -1 and n=10). The proposed methodology was successfully applied to samples of drinking water taken from different points of the water supplynetwork.