In situ formed 1-hexyl-3-methylimidazolium hexafluorophosphate for dispersive liquid-liquid microextraction of Pd(II) prior to electrothermal AAS and spectrophotometry


Abstract: 1-Hexyl-3-methylimidazolium hexafluorophosphate was prepared in situ and used as extractant in dispersive liquid-liquid microextraction. Ultra-trace amounts of Pd(II) could be accurately determined by electrothermal atomic absorption spectrometry (ETAAS) and spectrophotometry after extraction by the formed micro-droplets of the ionic liquid phase. 1-(2-Pyridylazo)-2-naphthol was used to produce a hydrophobic palladium complex prior to extraction. The effects of concentrations of reagents, reaction and extraction times, and the other parameters were investigated and optimized. Beer's law was obeyed in the ranges of 0.015-0.900 and 1.50-63.0 ng mL^{-1} Pd(II) by ETAAS and spectrophotometry, respectively. Under the optimized conditions, the limit of detection (LOD) by ETAAS was 3 ng L^{-1} with an enrichment factor of 460. The RSD percent was in the range of 1.3%-4.8% for various standard concentrations of Pd(II) in the range of 0.050-40.0 ng mL^{-1}. Most ions did not interfere. The method was successfully applied to the determination of Pd(II) in some water and alloy samples, jewels, and palladium catalysts.

Keywords: Palladium, dispersive liquid-liquid microextraction, 1-(2-pyridylazo)-2-naphthol, 1-hexyl-3-methylimidazolium hexafluorophosphate

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