Imidazolium-based task-specific ionic liquid for selective Ag, Cu, Pd and Pt determination by means of dispersive liquid-liquid microextraction and inductively coupled plasma optical emission spectrometry

Abstract

This work explores chelating capabilities of 1-butyl-2-diphenylphosphino-3-methylimidazolium hexafluorophosphate (BDPPIMPF6) as a task-specific ionic liquid (TSIL) for metal extraction/preconcentration procedures. To this end, metal extraction by BDPPIMPF6 for 21 elements (Ag, Al, As, Au, Co, Cr, Cu, Fe, Ir, Mn, Ni, Pb, Pd, Pt, Re, Rh, Ru, Sc, Ti, V, and Zn) were evaluated. This TSIL specifically forms chelating complexes with several elements of Group 10 (Pd and Pt) and Group 11 (Ag and Cu) of the Periodic Table. Chelating capabilities of BDPPIMPF6 has been exploited for developing a novel methodology for the simultaneous determination of Ag, Cu, Pd, and Pt by means of dispersive liquid-liquid microextraction and inductively coupled plasma optical emission spectrometry detection (DLLME-ICP-OES). This methodology afforded enrichment factors of 14 to 70 and limits of detection (LoD) of 0.2–2 μg L−1 for Ag, Cu, Pd and Pt. These LoD values were between 110 and 35-fold lower than those obtained by direct analyses with ICP-OES (i.e., no DLLME treatment). Finally, the proposed method has been applied to the analysis of Ag, Cu, Pd, and Pt in water and pharmaceutical products. Irrespective of matrix characteristics, quantitative recoveries were found for all the elements investigated thus highlighting methodology robustness.