Robust Ionic Liquid-Based Dispersive Liquid-Liquid Microextraction Method for Determination of Chromium(VI) in Saline Solutions

Robust ionic liquid-based dispersive liquid-liquid microextraction (IL-DLLME) is a fast and simple method for extraction and preconcentration of metal ions from samples with high salt content. This method can solve the problems associated with the limited application of the conventional IL-DLLME in these samples. In this procedure, the hydrophobic chelate of chromium with ammonium pyrrolidinedithiocarbamate (APDC) was extracted into the fine droplets of 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF6]), which was dispersed into the aqueous sample solution. Several factors that influence the microextraction efficiency were investigated. In optimum conditions a linear calibration graph in the range of 0.5-70 g L-1 of Cr in the initial solution with r = 0.9998 was obtained. Detection limit was 0.16 g L-1 and relative standard deviation (RSD) for 20 g L-1 of Cr was 2.68% (n = 10), respectively. The proposed method was successfully applied for the determination of Cr(VI) in water samples and food additives.