Ultra-trace Cr preconcentration in honey samples by magnetic ionic liquid dispersive liquid-liquid microextraction and electrothermal atomic absorption spectrometry

An analytical method based on the dispersive liquid-liquid microextraction (DLLME) technique, using a magnetic ionic liquid (MIL) as an extraction phase, was developed for ultra trace Cr determination in honey samples. The elemental detection was performed by electrothermal atomic absorption spectrometry (ETAAS). In the developed method both centrifugation and complexation of the analyte were not required. The Cr(III) species was extracted by the MIL trihexyl(tetradecyl)phosphonium ([P-6,P-6,P-6,P-14]FeCl4) after the formation of [CrCl2(H2O)(4)]Cl. The MIL phase was separated by a magnetic rod, diluted in CHCl3 and Cr was determined by ETAAS. Under optimized experimental conditions, an extraction efficiency of 98% and a sensitivity enchancement factor of 105 were achieved. A detection limit (LOD) of 5 ng L-1 Cr and relative standard deviation of 3.5% (at 50 ng L-1 Cr and n = 10) were obtained. Also, the linear range of the calibration curve was from 15 ng L-1 to 180 ng L-1. The method was applied for Cr determination in honey samples of different shades.